Need help with cooling!

[78zstyle]

You don't. This is covered over and over...

The ZX's used a three second fuel pump prime to refill the rail and combat hot restart issues.

 

Run a 160 thermostat in the summer to keep the blast furnace of the radiator only blowing 170-180 F air over your engine, and prime the fuel rail on restart before cranking and watch your summer heat soak problems go away entirely.

 

If I can drive across the desert southwest towing an 800# trailer without hot restart problems in Mid June in 120F+ ambient s, 91 should be child's play!

 

Personally, the fuel pump prime thing did nothing for me.

 

Others have fitted the injector fan with reported success, you could try that OP.

[cgsheen]

There's something else that's just not quite right here.  91 degrees??  He's got hood vents - or should have on his '78.  Guess what temp it is here in Phoenix (we're WISHING it was only 91...)  I've got no "hair dryer" on my turbo engine and it doesn't vapor lock to the "it won't start again until it cools off" point.  I daily drive Goldie no matter what the temp outside is, and ya, my A/C is running full bore.

 

IMO fuel prime is a necessity, the hair dryer ("injector fan" or auxilary air fan) is a band-aid (may help and will only hurt if it's just covering up the real problem). The OP needs to find the ACTUAL problem and get it taken care of.  Unless he's just being really nervous, an EFI Zcar shouldn't "not start" for 30 minutes after driving around in the "91 degree heat"...  (sorry for the scoff - we get a little testy in the desert this time of year   )

[NewZed]

Weren't you the one that proposed that it was fuel vaporizing on its way out overheated injectors that was the source of the problem?  Can't remember who said that.

 

I didn't have luck with priming the rail either.  But I did build my own injector cooling setup using a ZX blower and some GM heat riser tube.  Air blown directly on the injectors, with a timer to keep the blower on from shutoff for about 20 minutes (the critical time period for most people).  It was just an experiment but it worked so well that it's still on there and I always use it.  I forgot to turn it on twice, in the winter time, and the problem came back really bad.  Here in Oregon, I'm convinced that they use winter blend gas from early fall to late spring, and that's when it's worse.

 

Fuel quality as the other half of the problem could be why the automakers all went up in fuel pressure from mid-30s to mid 40s and higher.  I tried to find a low flow injector so that I could run higher pressure but didn't get anywhere.

[Tony D]

The injector prime is generally more effective simply because it's easier than setting up the fan properly---and the fan was added in conjunction with the fuel pump prime. The fuel pump prime also helps with a drained battery from extended cranking, and flooding of the car during times when it's not hot.

 

You can bandaid it all you want, but these things are SYSTEMS and if you choose to employ ONE of the fixes, you inevitably will be disappointed. I run around SoCal in 120 heat WITHOUT fuel prime and don't have a problem. With cheap CA Gas. But I know when I can try to start the car and when it will be fruitless so I don't event try. It means you wait 15 minutes. If I prime it, I can start it anytime. If I added a cooler blower, without prime there  is a 5 minute window where it starts, and a 10 minute time when it doesn't. It takes about 2.5 minutes off each end of the inevitable (in 120F heat)....

 

Now, if I run a 160F thermostat, there is MAYBE a 5 minute total window that it has the problem (instead of 15-20 minutes.) And if I prime it I have no start issues at all.

 

So add the bandaid blower, which adds weight, complexity and failure possibilities, or lower the operating temperature so you don't get so hot underhood? Hmmmmmmmmm...

 

If you guys are having hot restart problems "in the wintertime" you have some SERIOUS OTHER ISSUES and you need to get them fixed. I run crappy CA Winter Gas and NEVER have that problem in CA.

 

The FAN doesn't come on until 215F water temperature... If you need a fan during the winter, check your fuel pump check valve or something, you got serious problems, that fan should NEVER have to run except on the hottest days of summer!

 

That's the problem with anecdotal evidence and guys on the internet saying 'oh, that didn't work at all for me'....

 

When they say this, I want everybody following the thread to consider this:

 

1) a 160F thermostat was available for ALL Nissan Z's.

 

2) the fuel prime was added to ALL Nissan ECU's in the early 80's.

 

3) the injector fan was added on SOME S130's, not every one had it as I have seen. Same with Cedrics, Glorias, Leopards, etc... 

 

If it's added to everything, chances are it addresses something at a basic level (likely more than one thing.)

If it's added to some models, it addresses usually one thing in that specific model. If it isn't on every car in a particular model run, then those are very specific, chassis or application related fixes.

 

As I said, look at the conditions where the fan is supposed to operate. 215F+ coolant temperature. After the engine is shut off... If you are hitting that in the winter, fix the problem, not the symptom!

[Tony D]

newer cars have higher pressures for fuel volatility changes for atomization. Today's gasoline is like Syrup compared to the light aromatic blends used in the 70's which were high octane but vapor locked when underhood temperatures  rose (EGR thankyouverymuch!) Now they have non-return systems, so pressure means capacitance...higher pressure contains more potential fuel with less variation possible within a hydraulic system of a given line size. You engineer for sequential firing of the injectors and the resultant pressure drop and average the pressure  for delivery.

 

You will also note that the newer fuel systems (even as far back as the Z31) have a fuel temperature sensor, to feedback into the ECU for compensation of injection events. It's why the current crop of cars gets consistent fuel mileage. Prior to temperature sensing of the fuel, it was PURELY a volume issue. You injected "X" Volume through a pulsewidth. But that volume of gas was NOT consistent in BTU content. Temperature compensation allows for much more consistent combustion through much more consistent fuel volume (btu wise) than previously achievable in volume-only systems. 

[NewZed]

Lots of interesting factoids listed there.  But on my essentially stock EFI system, with N42/N42/N47 (intake/head/block) engine, and all the factory heat shields, new Nissan 180 degree thermostat (opened at 185 on the stove), new radiator, temperature needle rock-steady at a hair over center; the fuel rail priming and purging (new cool fuel run through it while waiting for fuel tank bubbles to stop) does not have any effect.  It just doesn't do anything.  The fan bandaid (fandaid?) has immediate and consistent effect.  If I turn the fan on when I leave the car, it doesn't matter when I get back, 5, 10, 15, 20 minutes, doesn't matter.  Get in, no priming, start engine, drive away.  Just like a modern car.

 

The only way it could get better, for my situation, is if I could find a decent automatic timer for a reasonable price.  The hundreds of Asia-made turbo timer options look interesting but seem way overpriced for what they are.

 

That's my anecdote and I'm sticking to it.  Priming doesn't work, fan on injectors does.

[NewZed]

As for why different people see different effects, location could be a factor, as described below.  We're not all using the same fuel.

 

http://www.google.com/url?sa=t&rct=j&q=gasoline%20blends&source=web&cd=9&cad=rja&ved=0CGoQFjAI&url=http%3A%2F%2Fwww.gao.gov%2Fassets%2F250%2F246752.pdf&ei=SuPiUdrCHqr-iwLbmYCYAg&usg=AFQjCNEtVR2slSlQyHx6vqE68Uou0MnJag&bvm=bv.48705608,d.cGE

 

 

Note the date - 2005.  Who knows how many blends are out there now with ethanol addition.

 

 

Here's another, newer, more general article - http://www.weeklystandard.com/articles/bureaucratic-gas_634424.html

Edited July 14, 2013 by NewZed

[78zstyle]

Lots of interesting factoids listed there.  But on my essentially stock EFI system, with N42/N42/N47 (intake/head/block) engine, and all the factory heat shields, new Nissan 180 degree thermostat (opened at 185 on the stove), new radiator, temperature needle rock-steady at a hair over center; the fuel rail priming and purging (new cool fuel run through it while waiting for fuel tank bubbles to stop) does not have any effect.  It just doesn't do anything.  The fan bandaid (fandaid?) has immediate and consistent effect.  If I turn the fan on when I leave the car, it doesn't matter when I get back, 5, 10, 15, 20 minutes, doesn't matter.  Get in, no priming, start engine, drive away.  Just like a modern car.

 

The only way it could get better, for my situation, is if I could find a decent automatic timer for a reasonable price.  The hundreds of Asia-made turbo timer options look interesting but seem way overpriced for what they are.

 

That's my anecdote and I'm sticking to it.  Priming doesn't work, fan on injectors does.

 

 

That's the problem with theory and guys on the internet saying "Oh this should work" when you have practical evidence of what works and what doesn't,

[Tony D]

"new Nissan 180 degree thermostat (opened at 185 on the stove),"

 

So with a thermostat opening 5 degrees late, and not full opened until 195.... meaning temperatures at the back of the head are AT LEAST 215-225F...

 

Like I said "Fix The Problem"! You car gets hot enough that the cooling fan would be required.

 

The 'bubbles in the tank' is a criteria I haven't seen before, and I don't know where that comes from. . . Since your car is overheating the BASE of the injectors, and they are not SIDE FEED (something else Nissan did on subsequent models) the cooling fan cools the base of the injector that will still be hot because of the temperature you are running the engine at....the base is hot enough to flash, and when the pintile opens, and the pressure drops, the gasoline flashes to vapor and the restart issues occur.

 

The root is the TEMPERATURE you run the engine at being too hot for the fuel quality.

 

This was mentioned in my SYSTEM APPROACH to the troubleshooting. You address the overheated bottom injector by running the fan. Again, having restart issues and 'requiring' the fan during the winter can EASILY be traced to your bad thermostat running 5-10 degrees hotter than it should. Cracking should happen 180 degrees, not 185. It should be fully opened by 190 (not 195)... Too hot tooooo hot!

 

Fine for 1975 fuels, not so great for current fuels run at 28psi.

 

"Practical Evidence of what works and what doesn't" isn't what this is, look at the REASONS for what is happening, and it all supports the engineering behind what they did at the OEM. If you're fine slapping something on there because someone says it works, without understanding why...have at it. But don't get PO&B when you start having problems down the road (like having hard starting issues when your fandaid wasn't turned on in the midwinter cool days) and you have (restart) issues!

 

Looking at the SYSTEM approach, that is the key. I stick by the statement that if you have hot restart issues in midwinter, there are serious issues with your car. That should NEVER happen! Not on even a STOCK 1975 280Z without ANY 'improvements'! If it does, there ARE problems, and your 'practical evidence' is not really applicable! It's a skewed vision. An Anecdote.

 

Riddle Me This: If I can simply run a 160 Nissan Thermostat, and NEVER have this issue EXCEPT on 110F+ Degree days in the desert after running for two hours at 80MPH towing an 800# Trailer... and my car is BONE STOCK (including the thermostat) what practical evidence does that add to the discussion. Because that is the status of my car, meaning you can go quite extreme before hitting these issues. Solve the ISSUES, not bandaid them to only have them surface later. FIX the ISSUE! These cars are universally improperly maintained, and when properly maintained these issues are simply not that big a deal, and you need do VERY little to 'solve' them when they do.

My 7/78 production 280ZX doesn't have a cooling fan for the injectors, and runs in the same climate as my 76, the ONLY difference is the fuel prime. 

 

Both are PROPERLY maintained. On the RARE occasion that the 76 stumbles on restart after a hot run on a 110F day, the ZX starts flawlessly. Only fuel prime is present in the ZX.

 

If this is happening "all the time" you need to go FIX YOUR CAR, not stick a bandaid or fandaid on it to limp it along another couple of months  until the weather's cooler and you get a 6 month reprieve...

[Tony D]

And I am far from 'a theory guy'! 

I have always been a practical applications person. I correct the theory guys regularly.

But being to explain the reasons for why something happens, or why it works is not 'theory', it may be supposition.... 

 

I spent a LOT of time accruing data on these type of issues. At least 18,000 miles on my 76 where I was instrumented with RTD's and Thermocouples all over the car.

The root of my understanding of the mechanics of what causes this issue is more than most. Similarly the prior year I spent 15,000 miles with the same setup on my 74 searching for the "Vapor Lock",  "Aftermarket A/C" and "Overheating" issues on the early S30's.

 

I can tell you POSITIVELY that the conditions, insofar as cooling goes, on that 100F+ Iowa day were BETTER than an 85F day in SoCal. Quantified and proveable in black and white ledgers of recorded temperatures. I have said well over 15 years that location had a big effect on what was going on with your car. And that HANDS DOWN, when it comes to heating/overheating/heat related issues SoCal/Arizona/SoNeVa are THE place to have those problems. ANYWHERE ELSE doesn't hold a CANDLE to them in terms of severity of conditions. There is a REASON every single car company in the WORLD takes vehicles to Las Vegas and runs them on a circuit through Baker, Death Valley, 93, Phoenix this time of year. One reason is that it's cheaper than running to Afghanistan to do it, probably the only other place with similar conditions.  If you can't "fix" a heat-related issue applying the same practices that clear it up in that region....THEN SOMETHING IS SERIOUSLY WRONG WITH YOUR CAR! It's not running right. And then, applying that which works to properly-running vehicles, won't work until such time as you FIX YOUR CAR FIRST!

 

If I can blast across Iowa at 100mph+, in 103F heat, with an engine temperature (with Aftermarket A/C on high...) of <180F and an interior cabin temperature of 70F without overheating.... I think I understand what is going on and have found the keys to issues most people have. (In SoCal in 85F heat my radiator thermal layer was 140F+, while in Iowa at 103F, it was barely 115F!)

 

A lot of it surrounds what are now well-established internet myths about this or that... that don't apply, don't work, or are just downright detrimental to the situation!

Each tried, recorded, and reviewed...

 

A bit further than most go when they slap something on there and if it lets them run, being satisfied.

 

What hose do you pinch off to drop the coolant temperature 5F at the rear of the engine? QUANTIFICATION of what does  what, and WHEN is important to understanding what is going on. Sometimes, it's not what you think!

 

Having time, and instrumentation, and knowing how to use it can be an enlightening time with these cars. Kinda like the Wind Tunnel Testing done here, it let us KNOW what worked, AND WHY. 

 

If you can't say WHY it worked, be open to the possibility that the guy that can tell you why might know what he's talking about. And the reason he knows this is not because he's 'an internet theory guy' but a real-world engineer with test instrumentation who really really really wanted to know what the hell was the real issue with all these people out there ignoring his suggestions and so he goes on a round-the-country trip taking monitoring data in the hottest part of the Northern Hemisphere's summer to gather the data and go evaluate it and draw some conclusions about what he spent time looking at. One circuit, across the northern route through Nevada, Utah, Wyoming, Nebraska, Iowa, Illinois, Michigan, Ontario, Wisconsin, Missouri, Oklahoma, NM, AZ, So Cal. The next year through So Cal, AZ, NM, TX, LA, AL, GA, SC, NC, OH etc....  That covers a lot of the area where people on this board exist and represents a great cross section of the possible data acquisition sets possible. High Altitude, Low Altitude, High Speed, High Load, BONE STOCK vehicles without modifications. As best a baseline data set as I could get to make/draw my conclusions.

 

I'm open to anybody who has documented their modification as well as I to share the data. But don't dismiss my suggestions as 'internet theory' because you want a simple answer like "I did this and it worked for me." That doesn't suit me as inevitably, someone comes back saying "I did it and it didn't work." At least I explained why, and can explain why most stuff doesn't when given enough data.

Edited July 15, 2013 by Tony D

[78zstyle]

His problem is occurring now, in the middle of summer. Not the middle of winter.

[78zstyle]

Anyways, as this thread is directed towards the OP's problem.

 

Both having the fuel prime and injector fan will either fix it, or at least help.

 

Forgot to mention, if possible use a heat shield between your exhaust and intake manifolds. Ive also heard of people wrapping their fuel rails.

Edited July 15, 2013 by 78zstyle

[Tony D]

One of the posted replies cited the injector cooling fan as the 'solution' because when it wasn't activated twice during the Oregon Winter, the car would not hot restart on both occasions.

 

It was my point that if THIS was the case, then other items are SERIOUSLY WRONG with the car, and discounting a logically-derived method for solving it, running concurrently with the OEM approach  may not be a valid conclusion, as it is derived from a bad data set, not congruent with the rest of the cars out there.

 

It's like saying the engine with a ventilated block has a starter problem and needs a gear reduction stater because the rod binds against the block and stalls the stock starter. Sure, a higher torque starter would probably allow the rod to bust out more of the block and continue cranking....

 

But you MIGHT want to fix that rod-out-the-side-of-the-block thing before buying another starter...

 

 

If it's been missed, remember that in TROPICAL environments the FIRST step is to put a 160F thermostat in there. That drops underhood temperatures SIGNIFICANTLY! I have recorded over 40-50F drop in some cases. Almost everything else after this point seeks to contain heat away from the injector bodies, or remove it from that area... But the FIRST step was to USE THE RIGHT THERMOSTAT FOR THE CONDITIONS PRESENT.

 

The later S30's vented the hood to let heat out.

The next step was more heat shielding and the WEBBED INTAKE MANIFOLD. (Along with a vented hood.)

The third step was the Fuel Prime (concurrent with the heat shielding and webbed manifold.)

The last step was blower fan, on SOME installations, where all prior steps were already taken save for hood venting on Cedrics, Glorias, Leopards, Laurels, etc.... The cars with unvented hoods got fans, some cars with vented hoods got fans (S130) On many of the UNVENTED HOOD applications, a PLASTIC VALVE COVER was used to suppress heat radiation above shielding in the unvented void, and to suppress noise.

[NewZed]

Seems like we're just looking at two different ways to keep whatever fuel system component it is that matters from getting too hot.  One is to run a cold engine (160 thermostat) so that residual heat doesn't transfer in to that component.  The other is to remove the heat from the component (via the fan) as it is transferred in, before the component reaches the critical temperature that cause the "heat soak" problem.

 

In choosing between the two you have to decide if running your engine at a cooler than design temperature all of the time is what you want to do to avoid 20 seconds of extreme aggravation.  Or if having a two pound electrical/mechanical band-aid is the way to go so that you can run your engine at design temperature (assuming that 180 is design, and 160 is not.  If 160 is design, then going to a 160 thermostat is obvious).

 

Aside from proving points with data (if I had the cash flow I would have a scanner and simple data-acquisition setup in my garage and it would have been used already for this and other issues - but thanks for sharing, I wish I had something similar to offer), the question at this point is what temperature to run your engine at.   I've never really understood the cool, normal and tropical thermostat options from Nissan.  The tropical and cold options seem like band-aids for a limited cooling system design.  In principle, the radiator, fan, water pump, coolant channels, etc. work together to keep the engine temperature stable at a set point, regardless of the climate.  The thermostat determines what that internal engine temperature will be.  You should change thermostats because you want the engine temperature to change, not because the external climate is changing. 

 

So, the evidence from the cooling fan and the thermostat experiments both support the idea that residual heat from the engine is the problem.  Now, what is the optimum temperature at which to run your engine?  If it's 180, then you need a fan or some other method to avoid the heat soak problem.  If it's 160, then put the 160 thermostat in and avoid the complexity of the fan.

 

Kind of how I see things.  I don't know what the best temperature is to run my engine.  Seems like Nissan would have made the 160 thermostat the standard if 160 was optimum design temperature and it removed the need for the cooling fan, for the ZX's.  But, maybe it's just a simple emissions or mileage issue and they had to stay with 180 as the standard.  Maybe 160 is better for power and longevity?  An "Optimum Engine Temperature" thread could get pretty long, I assume, but it would be interesting.

[Tony D]

NO!

It is NOT 'running a cold engine'! This is your basic disconnect with the engineering behind the Nissan L-Series. This is NOT a modern vehicle. This is a vehicle designed around REGULAR maintenance intervals. In fact, changing a thermostat according to ambient environment IS INDEED CALLED FOR! 160 in the Summer, 170 or 185 in the winter. THIS IS THE WAY IT WAS DONE BACK THEN. You do not run it 'too cold all the time'.... I run 160 year-round now, but for YEARS when I drove in to the mountains and would get to zero or at least below 30F I would run a 180 fall to spring. If I don't go where it's cold, it stays 160 as the criteria for it (never getting below 40 F) don't exist to change to one that runs hotter. You have a basic misunderstanding of what design criteria exist for an ICE.

 

In EVERY CASE, the 160 "Tropical" thermostat is AVAILABLE for the automobiles in question.There are predetermined criteria for it's selection. Much like they gave you a chart for selecting your OIL VISCOSITY. Chances are if you are in 'tropical' climate you can get by with straight 40 weight oil, and there is no need for multi-vis.

 

160F Thermostat IS A DESIGNED THERMOSTAT FOR THE APPLICATION.

 

It is NOT 'running it colder than designed'---if you choose to use that terminology I call you out here and now to show me the NISSAN DOCUMENTS that show us what the 'design temperature' was! This goes to a basic misunderstanding of the effect of water jacket temperature to oil temperature. ICE are designed around OIL TEMPERATURE not WATER JACKET TEMPERATURE. But that is for a different time. FACT of the matter is in HOT environments, the NISSAN DESIGNED THERMOSTAT is 160F! Not a SINGLE sensor or function will be affected by running this thermostat on an EFI Vehicle.

 

You want your oil temperature up to 180F as soon as possible. And the 160 thermostat will NOT allow the oil to EVER get colder than 180F. And for THAT reason Nissan does NOT and has NEVER made a 150F thermostat available for these vehicles. But a 160 IS available.

 

Now, understanding this, you see that the FIRST LOGICAL STEP is to drop your thermostat temperature to 160. This keeps your oil cooler, and everything under the hood cooler. Emissions concerns were addressed later, and they really don't apply to this discussion. That was done on LATER engine designs, not the L-Series which was designed in the late 50's early 60's! There is NO 'mileage impact' for running a 160F thermostat, your sensors all will get to 170 with that thermostat in there, if not hotter. This will completely remove any and all 'cold start' or 'warmup' enrichments. 

 

Actually, for POWER the argument can be made for a HOTTER thermostat as losses are less. But that is THEORY and benchracing. We are talking here about PRACTICAL applications, and the 160F thermostat keeps the underhood temperatures lower. It keeps the  oil cooler. BOTH of these are desired effects. The oil does NOT go lower than 180 EVER. In fact it's likely closer to 200 in this instance, depending on where you monitor it. 

 

But saying 160 is not a DESIGNED COMPONENT is simply wrong. It is. When the heat outside is 90F, there is NO REASON to run a 180F thermostat. It delays cooling of the oil, resulting in spiking above ideal temps. You are trying to apply ONE thermostat to ALL applications, stating things like "OPTIMUM"---well that DOESN'T EXIST. 

 

Depending on CONDITIONS you run different thermostats. The reason? Because even Nissan realized "THERE IS NO BEST"---no "magic bullet" -- no "one size fits all" and FOR THAT REASON the three thermostats exist. 

 

Frankly, unless you are in Thunder Bay Ontario, nobody needs "Frigid" thermostat. It's meant for operation in subzero conditions for extended periods, and ambients which don't exceed 30F. If you don't exceed 20C / 70F you run 'temperate' and if you exceed 30-35C / 90F you run "Tropical"....

 

I can warrant there is BRISK TRAFFIC in the "Tropical" thermostats in Malaysia, where it stays 32C all the time, Thailand, where it might hit 27 during the coldest part of the rainy season but otherwise is 30C+++ the rest of the year. If you are in a continuous daytime  temperature of 30C or above, you need thermostat "TROPICAL"

 

Now, couple this with the Aerosols Diffusion of UV Radiation, where SoCal at 85F/30C runs a 60C airflow through the radiator, and at 45-50C it's 70-75C through the radiator you realize that a 72C thermostat will be opening EARLY.... Run an 80C thermostat, and you will BOIL in the engine as there won't be flow to cool the rad sufficiently, not to mention what happens to oil temperature.

 

If it's only 21C out, SURE, go ahead, run an 80C Thermostat. No harm no foul... But 30C? In Southern Deserts where your radiator thermal layer is 60-70C? Underhood will be HOT HOT HOT and even HOTTER with a higher thermostat.

 

Go search on KTM's experience in So Cal with runaway temperatures in his Z after coming off the highway and sitting on a ramp. Once he put the 160/72C thermostat in it didn't repeat. Go to the Grape Ape Racing page and read about nucleate boiling. This is more than injector heat soak.... Each component has several solutions, but as a SYSTEM you have to balance them to get the best mix of advantages. Running a 24psi cap will keep your 190F Thermostat from boiling in almost every instance. NEVER have a boil-over issue. But now you got 215F heat radiating all over under the hood. And you got injectors failing,  frying, etc....

 

Now, put that 24 psi cap on, run a 170 thermostat, or a 160 thermostat, you NEVER boil over (it still may be getting to 200 at the back of the head, but it doesn't start nucleate boiling) and you have dropped your underhood temperatures significantly.

 

What is a good SYSTEM approach, taking in all the variables? A fan pumping air from the starter area works to some extent, but it doesn't address heat generation. 

 

The root is heat GENERATION. Don't generate any more heat than is NECESSARY. That is the KEY. It's what Nissan decided back in 1969, but Americans disregarded and continued to have problems with their cars for decades afterwards. There is complexity to this, there is no 'best'.... there are sets of conditions, and you choose what's best for those data sets.

 

And from my testing, once you get over 80 degrees, if you don't run a 160 thermostat, you have A LOT MORE ISSUES ON EVERYTHING UNDER THE HOOD, than you do if you run a hotter thermostat.

 

Now, it's your choice to make. You can choose to have issues, or avoid issues. If you have them, don't discount that there may be a simple answer.

 

As the OP said, 'I will try the thermostat' and I support that thought.

 

That IS the first step over 80F. If that doesn't work, start looking deeper as to what is going on.

[Tony D]

The statement 'remove heat from a component' is secondary thinking.

Engineering thinking, primary thinking says "don't put the heat there in the first place"!

 

And that was the impetus for the different thermostats. "Run only as hot as necessary to obtain oil temperature that is suitable."

 

The "Standard" designation for 180 thermostats come from US VEHICLES. Nissan called them "Tropical" "Temperate" and "Frigid" and it all revolved around short trip heatup. INDEED the temperature you operate at determines when you want the thermostat to open. If you have never run a diesel in -40 you wouldn't understand that even 190F thermostats DON'T WORK and you have to block the radiator (or some rigs use thermostatic baffles to block airflow through the radiator) so any circulation doesn't cool the coolant too much.

 

 

"Seems like Nissan would have made the 160 thermostat the standard if 160 was optimum design temperature and it removed the need for the cooling fan, for the ZX's.  But, maybe it's just a simple emissions or mileage issue and they had to stay with 180 as the standard.  Maybe 160 is better for power and longevity?  An "Optimum Engine Temperature" thread could get pretty long, I assume, but it would be interesting."
 

They did make it standard, when operation was above 30-35C

They made an 80C thermostat standard when operation was below 25-30C

The made an 85C thermostat standard when continued operation was did not exceed 10C

 

Insofar as emissions, there are some parameters for that, be we aren't talking about a ZX here, we are talking about an S30. The ZX's always ran HOTTER and as a result had extensive auxillary fans on the radiator, venting in the hood, etc. The 160 was still an optional thermostat listed in the parts catalog, with the same criteria for application.

 

MOST of North America falls within the "Temperate" zone, so an 80C thermostat would be called for most of the year. In the North, or Canada it could be argued an 85C would be "Standard" and there would likely NEVER be a condition that would warrant a 72C Thermostat. Maybe an 80C.... but why bother for 5 degrees if it's only a month a year?

 

Southern States, however, and the desert southwest in particular DO hit the criteria of "Tropical" Thermostat application at least 6 months out of the year. 

 

Similar to picking your oil viscosity....and not relying on multi-vis. 30WT in the winter, 40WT in the summer. Perfectly acceptable, and doing semi-annual maintenance changing a thermostat is no big deal.

 

What you will note is a curious tendency in Nissan's Stock Thermostat selection:

72C=162F cracking, fully open by 180 temp at #6 <200F (with Water Wetter and 16psi cap) Clutch Fan INTERMITTENTLY would engage when going uphill towing 100F+.

80C=176F cracking, fully open by 194 temp at #6 214/224F (with Water Wetter and 16psi cap) Clutch Fan Intermittently would engage when towing flat above 110F

85C=185F cracking, fully open by 200 temp at #6 220F/??? (with Water Wetter and 16psi cap) I tended to get runaway cooling issues running this thermostat with new water pump and four core radiator at 110F day at 80mph steady speeds, even with water wetter and properly operating clutch fan setup. The clutch fan was engaged almost continually even going in level travel. Clutch fan engages aroudn 215-220. Coil Temperature was 240F+ like this... everything under the hoot was COOKING with this setup.

 

What you will see is that with a 160F thermostat, you actually run 180. HOTTER at the back of the engine, and FULLY SATISFYING all of the EMISSIONS requirements by actuating the 176F requirement for enabling of EGR, etc.

 

The "STANDARD" (Temperate) "emissions" thermostat holds the water flow off the engine until AFTER the sensors are all above 176 before CRACKING the thermostat. This thermostat enables 'closed loop' and EGR as quickly as possible. If you go start your car with a 72C and an 80C thermostat, and drive up a ramp to freeway speed in 2 minutes, they will not have any appreciable affect on emissions engagement whatsoever. On an 80F day. On a 40 F day there will be a difference, especially if you are idling around town. But then you should have the temperate one in there as you are operating at 10C, now, aren't you? They referenced a MINIMUM temperature for employment of the 72C thermostat, and a Max/Min for the 80C thermostat. And a 'continually below' criteria for the "Frigid".... 

 

The "Frigid" thermostat holds the thermostat closed quite a bit longer, but in NO CASE is the thermostat NOT opened by around 180F. The rejection of heat from the oil pan can be significant when colder, and can result in oil too cold to do a good job lubricating. So you let that engine block get good and warm before cooling it.

 

Referring to thermostats by their cracking temperature, and using the wrong units (F Vs C) gives false information on what happens in reality.

 

Really, the Nissan Engineers DID KNOW what they were doing. Honestly! That's why they allowed a 72C thermostat on EVERY L-SERIES 68-83...

 

 

 

Now, if you never do maintenance on the car....well... that may be a root as well!

Edited July 15, 2013 by Tony D

[NewZed]

 using the wrong units (F Vs C) gives false information on what happens in reality.

I have to disagree with this statement.  Units are irrelevant, they describe the same reality.

 

It seems like the essence of what you're saying is that the purpose of the three choices of thermostat is to keep the oil above a certain operating temperature.  Apparently, because radiative cooling from the block and the oil pan overpower the control by the coolant circulation and radiator, keeping heat in the block maintains oil temperature.  Therefore, once you're above that temperature your next worry is overheating.  Makes sense since the thermostat is really a heat-retaining device, not a coolant flow inducing device.

 

The anecdotes from KTM and Grape Ape are interesting but, in my case, here in Oregon, I have zero over-heating problems.  I just got stuck in 3 mph, stop/go traffic out here on a hot afternoon in the sun for 40 minutes and thought for sure that I would see a sign of overheating if I was ever going to, at least the Temp needle creeping a little higher.  It didn't budge.  I don't have overheating problems, no signs of nucleate boiling, no overflowing coolant reservoirs, burping or bubbling from the over-flow tube, none of that.  Signs are that I don't even get any in- or out-flow from the reservoir (I've checked), expansion and contraction of the fluid seem to be taken up by the flexibility of the hoses.  My cooling system seems to work perfectly in removing heat.  I've checked my thermostat housing with an IR gun and my thermostat seems to work perfectly in retaining heat.

 

So my only reason to go to a 72 degree thermostat would be to stop the heat soak problem.  My system meets all other design requirements, oil is hot, engine stays cool.  So I'm still at the question of what is the best temperature to run my engine?  Since I like performance - both on the high end, raw power, and the basics like a smooth idle, clean-smelling exhaust, crisp engine performance - I would make a change for things like that.  I don't see any evidence that the 72 thermostat will offer that.  And I am sitting right where the Nissan engineers intended me to be, by their own instructions in the FSM.

 

At this point though, I would make the change just to see what happens, but Nissan (Courtesy Parts in this case) doesn't appear to stock them anymore.  They have the other two, by part number, but not the Tropical.  I don't like the aftermarket alternatives and that would be mixing variables anyway, so I'm stuck until I find an OEM Tropical thermostat.  Hopefully I'll find a decent source, and can take a look at any performance effects (tiny of course, from a HybridZ perspective) of running 72 versus 82.  It will still be anecdotal, based on how things feel and sound, but worth a look.

 

Where's the OP?  He should have something to say by now...

 

 

Edit - apparently the Nissan L6 Tropical thermostat part number has been superceded to 21200-F3160, for any future readers.  Shows up as a 1984.5 Pulsar NX part on the interweb, but the dimensions must be right.  Has 160 in the part number so the odds are decent.

Edited July 15, 2013 by NewZed

[Pharaohabq]

So this is quite the interresting conversation. A questions here just to make sure I have my head wrapped around this:  All three thermostats would certainly work in the same car and Datsun provided guidance for them.  In my 280Z's I've never had to change the thermostats, they work fine down here in the desert SW. So I'd assume they're either the 160 or the 180 deg thermostats. BUT in my 260Z, we have heat problems all the time. We've hunted down replacement heat shields and put in a new Thermostat. I believe it's a probably a 180, we never checked, it's just what Autozone gave us.  I wonder if a 160F would help the Vapor locking issues we're always having?

Edited July 15, 2013 by Pharaohabq

[NewZed]

Pretty sure (I hope) that we've been discussing EFI.  Your 260Z carbs are a different scenario, I believe.

 

Your 280Z's are interesting.  Are they still EFI and do you have any details on the injectors, insulators, etc.?  In all of the discussion, the mechanism of what actually happens hasn't been clearly defined.  You're down in the DOE's national lab zone, maybe they get better gas.

 

The thermostats have the temperature rating stamped on them, I think, along with the part number.  If you ever get a look, post the numbers please, it will be one or two more data points.

[Tony D]

I can not discuss engineering principles with someone who refers to the Grape Ape Racing article on nucleate boiling as "an anecdote", and who clearly skips large swaths of discussion where clear mis-stating of them occurs in a subsequent comment. You say things I never said, and go all over the place with Oregon stats I said it OVER AND OVER AND OVER: if you're overheating there... YOU GOT SERIOUS PROBLEMS (as I have repeated time and time again, coming from the most serious overheating region of the USA...) What really does someone have to offer if he has not overheated, and studied it in depth? Don't overstate what I'v found, nor twist extreme examples offered into something that supposedly happens all the time (which you have done several times with my comments now...) I have ZERO overheating problems as well, in SoCal, and driving across the desert southwest. If you don't have overheating problems in Oregon how is that applicable to a guy who IS overheating in Oregon? Or any other southern state? If you want a topic to explore what YOU want to know ("What thermostat is BEST for my application?"), START IT, don't muddy the discussion of someone WITH a problem giving unrelated anecdotes and unsupported stories. It's  interesting you search and find that INDEED a 1984 model has a 160F thermostat available.... seems maybe I speak the TRUTH on this subject? I didn't say anything to address OREGON and engines 'BEST' thermostat---I only addressed the issue of OVERHEATING ANYWHERE IT OCCURS.

 

Go do whatever shade tree approach you wish, don't muddy the waters for people who want to learn the truth on subjects. Exempting Oregon from the data set of the rest of the earth is as obtuse as calling the Grape Ape Site "anecdotal".... You could not have read it if you called it that. I can't see why, in Oregon, with no signs of Overheating whatsoever you would even CONSIDER running a 72C thermostat, you have a serious comprehension problem with what is being discussed and what has been stated SEVERAL times  now... This post was for an individual WITH supposed "Overheating" problems. NOT about performance thermostats. NOT about 'THE BEST' thermostat to run. In fact, the thought of "Performance Thermostat" is once again a holdover from Domestic Performance Lore where guys put in 160F thermostats... but let's not even go there. I believe I said "FIX THE PROBLEM".... "3/4 Gauge" will normally elicit a 'did you use a meat thermometer to VERIFY THE TEMPERATURE?' response. As chances are good "3/4 Gauge" whatever that equates to, IS NOT "overheating" but more likely "Gauge Drift"! But to the core issue of vapor problems as originally stated the check valve is a very common cause (if searched) and IF it indeed is 'overheating' then that is a cause, but the 'overheating' needs to be addressed as the primary concern as one leads to the other, but not vice-versa (no hot restart will cause overheating, but overheating will cause hot restart issues...)

 

As to "Units are irrelevant":

The thought that a 160F thermostat opens at 160 and is fully opened "10 Degrees  Later" by 170 is WRONG! It is an original 72C open by 82C  (162 to 180F) is the ROOT of the ignorant internet engineers saying "the 160 thermostat overcools your engine and interferes with your EFI cold start and emissions" because they are predicated on 176F triggering (IN ACTUALITY 80C TRIGGERING POINTS BY DESIGN) -- I deal with this conversion BS all the time. The thermostat spec is 72C with a fully open specification 10C later. 10F IS NOT 10C and therefore I discount your dismissal of the importance of units---please THINK about these things, instead of taking such a topical approach. We were discussing DESIGN PARAMETERS. Nissan didn't design or specify in "F" they did so in "C"... UNITS ARE NOT IRRELEVANT! Ask the JPL guy who made a conversion error and missed MARS by a couple of million miles. What an incredibly obtuse statement to make. "The same reality" only applies if that reality doesn't impinge on L-Series Nucleate Boiling Tendencies in hotter climates. Which the upper ranges clearly do in hotter desert/southern  climates! BRISK sales of 72C thermostats in Latin America... Does Oregon in his region have continuous temperatures below 0C for months on end? Maybe then an 82 or 85C thermostat is permissible or even necessary, but does it get warm? 91F = 32C, that's in the range where it is permissible to apply the 72C thermostat. Chances are it's FUEL RELATED (as stated several times previously, likely check valve, etc...)

 

If you are unwilling to expand your mind to different, more technical discussions and want to stick with anecdotes, only drive at night... because overheating is caused by sunlight. Every time I overheated, it was during the day, and the sun was out. I never overheated at night, therefore the sunlight causes my Z to overheat. This is somewhat akin to saying because your car in Oregon doesn't overheat using an 82C thermostat, that no car anywhere else will, either. The ONLY place you can make a statement like that is when you are in the HOTTEST portion and MOST SEVERE climates. I would not proffer advice on arctic operations living where I do currently, but in a long life and living in places that stay -40 (F AND C) for months at a time I can also do that. Don't hate for experience, dude!

 

Pharaohabq, absolutely it will help. Water Wetter and a 160F thermostat will significantly help with your 260's issues. My introduction to it was going to the ABQ Convention in our 260Z years back. NM is a little different that other parts of the DSW as the altitude contributes some other factors, not the least of which is altitude density which will affect further the cooling rejection of the radiator, and lack of UV Cover at high altitude like ABQ (those nice dark blue skies) make for one hell of a thermal layer, mixed with less dense air for cooling... Double Whammy! It's not uncommon when specifying electric motors in your region that 'bigger" motors or oversized cooling fans are called out to compensate for these factors (mostly altitude density) when desiring to keep the same shaft horsepower available for the equipment. Similarly aero design of centrifugal compressors are also tweaked to get the same delivery as required for the same application at lower altitude. Believe it or not, what we discovered was the effect of underhood temperature on return fuel. If you lower your thermostat to 160, the temperature of the fuel returned to the tank drops significantly. This helps with the vapor lock issue. But it's  a given volume, eventually you reach a stasis point in the tank where decreasing tank volume no longer acts as an effective heat sink and the temperature starts rising. This even affects EFI systems without a fuel temperature sensor, throws AFR's all over the place if you start  with 85F fuel, and end with 120F+ Fuel! A bodge we did on a 73 240Z was to convert a 1 gallon Coleman Water Jug to a 'fuel cooler' in the parking lot of the racquetball complex there in ABQ. Ran a coil of copper tubing inside, and put in 7# of ice. The car experienced ZERO vapor lock issues afterward. The ice would run out to water, and then the water start heating up to around 120F in 110F ambients over 2+ hours of highway driving. Basically as you had to stop for a tank of fuel (every two 1/2 hours or so, 240 miles more or less) you drained the water and refilled with ice. No matter WHAT we did, that car didn't stumble from fuel pump not making delivery. Keeping the fuel below 120F seemed to stop the vapor lock issues. This mirrored my experience driving the Baker Grade to the 2001 Convention as well, and JeffP's dyno experience. Assembling a variety of similar symptoms makes a nice data set to start formulating conclusions and and engineering solution. 

 

One of our Z-Car Club Members (a retired Engineer) worked extensively on heat shielding on his car, up to and including thermal barrier isolation to prevent conduction transfer of heat from the head to the fuel rail. Mounting the rail on silicone isolators, so that the steel lines never contacted the steel props on the head. This reduced his fuel temperatures significantly. Additionally he insulated the fuel rails from convected/radiant heat with the standard styles of reflective foil and glassfibre wrapping. This almost completely solved his issues. The last 'lark' he tried was on my suggestion taking a power steering cooler and placing it in airflow to cool the return line fuel. (Something now offered from performance houses 15 years later...) He reported this was also fairly effective. Not a 1 gallon jug of ice in hanging over the starter bandaid, but a systemwide approach to the root issue of fuel picking up heat from the engine bay and then getting to a point where it can not be effectively pumped and vapor locking occurs. (Of course, in the quest for less captive emissions, OEM's went with non-return systems so the heat doesn't go back to the tank.) PM me and I can send him an e-mail with your information. He's still on Earthlink and needs to 'invite' you to e-mail him before he will correspond directly with you. He has a good database on his examination of the vapor locking issue in his car (a 72 240Z Automatic) and his close to 5 year project to get it driveable on today's fuels. A project, last I understand, was now working towards and EFI conversion... LOL

 

My bet on the OP, BTW, is that the thermostat solved the problem or greatly alleviated it. As Nissan intended. Having 200F air blowing around  your engine bay is a bit more strenuous to clean air blend fuel than having 180F air blowing around. This is a direct reduction of 20F, and the ability of it to transfer to the tank and heat the fuel is equally reduced. The OP did not post what fuel level he had when this happened, but my bet, from my research, is that it was below 1/2 tank...and likely below 1/4 tank when this happened. 

 

Observation is the thing that turns anecdotes into research, and research into understanding. If you choose not to observe, you will never understand.

Edited July 16, 2013 by Tony D