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Head cooling on cylinder #5 - solutions?


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  I assume you did try to source the LD pump in Australia, I saw a thread and you mentioned you got it from Japan (?)

My thoughts on the Summary:   - The path of coolant through the L engines results in the rear of the head receiving the hottest coolant having stagnated water flow, insufficient for the he

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I think JeffP has run stragiht Etheylene-Glycol in his engine since new, and the head looks like new, no corrosion whatsoever. The boiling point of E-G is up there in the same area as the stated values of the Evans stuff, I wonder what the thermal transfer properties are in comparison?

 

I have run straight Etheylene-Glycol before and I noticed a significant reduction in cooling ability. Personally I wouldn't recommend it. As soon as I added water to change the mixture to roughly 50/50 the engine cooled much better. Just my experience....

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I have run straight Etheylene-Glycol before and I noticed a significant reduction in cooling ability. Personally I wouldn't recommend it. As soon as I added water to change the mixture to roughly 50/50 the engine cooled much better. Just my experience....

Yeah, EG is to extend the boil temperature, but it sacrifices heat transfer. Straight EG would only be used if you were extremely concerned about it freezing or boiling.

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I have a car that won't be driven in freezing conditions ever, but is driven on the street and perhaps a track someday (gotta get chassis stuff up to snuff). Can this be mixed with straight RO/water and no EG or other items for this condition? It says thus on the summit description but I wanted your guys' opinions on that.

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Corrosion has always worried me. I have suffered many engine failures due to corrosion. Exhaust ports on E31s blow through, freeze plugs pinhole, general failures of the metal plumbing in a "free" Mk1 MR2. I think I even suffered a headgasket failure due to corrosion once.

 

I use Redline's Water Wetter in the dosage recommended on the bottle. If I recall correctly... I only used part of a bottle with a complete fill of the cooling system.

 

The Redline/water got dirty much faster than usual. I have always had a slight water discoloration with this engine due it being drained(partially) and stored for years. This may be due to Water Wetter's surfectant properties, but it does not discolor as badly when I use 25% Antifreeze with the redline water mixture.

 

I have also tried using the Cooling system flush treatment to clean the cooling system. It made little difference. I change the coolant as soon as it begins to get really dirty, At least once a year.

 

It seems that the buffering agents in Antifreeze are consumed after a realatively short time in my engine. I run this car on track most of it's milage, so I expect more wear and tear. I change my oil before every event. I change my brake fluid every 3 months. Tranny and diff every few events. I am concerned that the Water Wetter does not properly protect the engine from corrosion no matter how fresh it is.

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Corrosion has always worried me. I have suffered many engine failures due to corrosion. Exhaust ports on E31s blow through, freeze plugs pinhole, general failures of the metal plumbing in a "free" Mk1 MR2. I think I even suffered a headgasket failure due to corrosion once.

 

I use Redline's Water Wetter in the dosage recommended on the bottle. If I recall correctly... I only used part of a bottle with a complete fill of the cooling system.

 

The Redline/water got dirty much faster than usual. I have always had a slight water discoloration with this engine due it being drained(partially) and stored for years. This may be due to Water Wetter's surfectant properties, but it does not discolor as badly when I use 25% Antifreeze with the redline water mixture.

 

I have also tried using the Cooling system flush treatment to clean the cooling system. It made little difference. I change the coolant as soon as it begins to get really dirty, At least once a year.

 

It seems that the buffering agents in Antifreeze are consumed after a realatively short time in my engine. I run this car on track most of it's milage, so I expect more wear and tear. I change my oil before every event. I change my brake fluid every 3 months. Tranny and diff every few events. I am concerned that the Water Wetter does not properly protect the engine from corrosion no matter how fresh it is.

 

OK, thank you. Good to know.

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Most industrial guidebooks say that anything more than 20% EG will effect heat transfer, so on stationary compressors or other equipment in closed-loop systems we will try to use water with treatments when at all possible, and no more than 20% E-G for maximum heat transfer/inhibiting.

Drewguard from Drew Chemicals will inhibit corrosion and make a nice, tanish phosphate coating on exposed metal that prevents bad corrosion, but I don't know that it comes in anything but a 55 gallon drum!

 

One thing EVERYBODY should do, is test their coolant with a Litmus Strip. You should be slightly basic (above 7.5) Usually 7.5 to 10 is what you will shoot for... If it's below that point, it's acidic (duh) and will exacerbate the dissimilar metals (alunminum / cast iron) issue as well.

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One thing EVERYBODY should do, is test their coolant with a Litmus Strip. You should be slightly basic (above 7.5) Usually 7.5 to 10 is what you will shoot for... If it's below that point, it's acidic (duh) and will exacerbate the dissimilar metals (alunminum / cast iron) issue as well.

 

Tony,

 

Isn't this similar to sticking a DVM probe in the coolant and checking for voltage? If so, what's a realistic acceptable voltage level?

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I don't know the conductivity number. It is related, but you can get litmus strips cheaply and it gives a good indication of basic/acidic.

 

A conductivity test will tell you about free electrons in the water, something that can effect corrosion, but it can be either basic or acidic...of course free electrons with a basic solution will not be a real problem, but excess free electrons in an acidic environment will cause runaway corrosion!

 

The tests go hand in hand, and NOBODY should be running their anti-freeze more than a year or two, regardless of what the litmus paper says!!!

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Isn't this similar to sticking a DVM probe in the coolant and checking for voltage? If so, what's a realistic acceptable voltage level?

 

I think Grumpyvette might know as he talked about it in his anodes thread, and wouldn't it be pretty universal?

 

Also, is the bypass near the #6-5 cylinder needed or can it be blocked off?

(What originally goes to the heater core)

 

Mario

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  • 2 weeks later...

O.K. I'll post the anecdote.

 

I drove my 260Z from LA to ABQ for the convention. This car would get hot in the desert with a three core and a 160 thermostat if you were pushing 80+ mph in 110+ heat. What I noticed was that every time we stopped for gas, the car would 'puke over' from the overflow, and you could hear the steam popping in the coolant system after shutdown. All in all, I puked a whole gallon out in 1500 miles of driving.

Fast Forward:

Same Car, same everything, but going to Kingston Ontario for another convention. Decided to drain the coolant and replace with EG mix 50/50 and Water Wetter. It was simply 50/50 EG before, so the only difference was the addition of the WW. Now, knowing I used a gallon of top-up fluid in my 1500 mile run at ABQ, I decided to make up 2 gallons for the Canada Trip...and once there could refill those jugs for the trip back.

I drive on with the water wetter in there, going up the Baker Grade on I15, the car starts to surge a little bit, but nothing like what we had the previous year when taking across the same stretch out of Barstow. My first fillup I'm interested to see that there is no 'pukeover' from my radiator. Concerned that I may have boiled a bunch out I relieve pressure and check again...radiator is full. Hmmmmm. Then I realized I didn't have any 'steam sounds' coming out of the thing, either. I start watching closer as I drive at altitude, across deserts, and at high rates of speed with the A/C on (110mph across Iowa, in 103 degree heat, with an interior temperature of 70 degrees A/C unit running full blast!!! Temperature on the gauge: left of center by a needlewidth!) During the whole trip never went past 190 degrees observed, and I didn't use a DROP of makeup fluid. The car just didn't 'puke over' after shutdown like it did before adding the Water Wetter.

 

So I think the Water Wetter stuff does have an effect on heat transfer, and makes for more efficient cooling. I use it in all my cars now, and notice similar results. If it wasn't for the lack of pukeover (which the car WAS doing not a week before the trip when I was doing shakedowns and picking up the supplies to do the glycol change) I would not have made the connection between the ONE component in the system that had been changed.

 

The heater connection near the back side of the head is just that: a heater connection, nothing more. It gives the heater a nice hot watersource before the thermostat opens, and as it's opening still has a good hot supply of water to feed the heater core. When the heater is off, there is no bypass function. During warmup, it does serve as a bypass IF the heater valve is activated to give heat to the cabin.

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One more thing I forgot to mention on my post was that I blocked off the below coolant port in the front of my block. This port was added only to protect the engine in the case of a plugged radiator. If left open, some coolant is allowed to bypass the radiator completely. Since I will never have a plugged radiator and I always watch my gauges I tapped and blocked this hole so all my coolant went through the radiator.

 

 

L28block.jpg

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That is the 'internal bypass port' I talk about continually, which others have said I'm crazy and which doesn't exist!

That port, in conjunction with the 10mm line off the lower thermostat housing are what are in the system to prevent Water Pump Cavitation from a zero-flow situation before the thermostat cracks and allows flow to the radiator.

If you rev the engine, the thermostat will open (it's only spring loaded) due to pressure buildup, but for idle warmup that passage and the one in the lower thermostat housing are the only way the water pump can circulate the coolant around the block without deadheading.

 

IF YOU OPEN YOUR HEATER CORE CONTROL VALVE SLIGHTLY IT DOES THE SAME THING.

 

People many times remove the external bypass, but a lot of them ignore this internal one---which usually is the only one that keeps the water pump from deadheading against the closed thermostat during warmup.

 

If you have a F/O style setup, or external lines venting the head that bypasses the thermostat, these holes/bypasses are not required.

 

And again, even if you don't, cracking your heater core will allow the flow and prevent water pump / water pump housing damage from deadheading during warmup.

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That is the 'internal bypass port' I talk about continually, which others have said I'm crazy and which doesn't exist!

That port, in conjunction with the 10mm line off the lower thermostat housing are what are in the system to prevent Water Pump Cavitation from a zero-flow situation before the thermostat cracks and allows flow to the radiator.

If you rev the engine, the thermostat will open (it's only spring loaded) due to pressure buildup, but for idle warmup that passage and the one in the lower thermostat housing are the only way the water pump can circulate the coolant around the block without deadheading.

 

IF YOU OPEN YOUR HEATER CORE CONTROL VALVE SLIGHTLY IT DOES THE SAME THING.

 

People many times remove the external bypass, but a lot of them ignore this internal one---which usually is the only one that keeps the water pump from deadheading against the closed thermostat during warmup.

 

If you have a F/O style setup, or external lines venting the head that bypasses the thermostat, these holes/bypasses are not required.

 

And again, even if you don't, cracking your heater core will allow the flow and prevent water pump / water pump housing damage from deadheading during warmup.

 

The port does exist...but you are still crazy. :D Not sure what you mean by "F/O setup". I still have the 10mm line below the thermostat. I actually run that line down to my turbo and back up to the heater hose T on the right side of the block. I would think this would keep the waterpump from stalling even with the bypass port blocked. I don't want to have to remember to crack my heater core open.

 

If the waterpump was "deadheaded" how would it it damage the water pump or housing? I would think the engine would over-temp long before that would happen.

 

Also, I've been thinking about trying to modify Mr Gasket hi-flow thermostat just to ensure it opens only when it's suppose to. Either way, I think the 180 degree thermostat is a good trade off for proper cooling but still hot enough for the engine to operate efficiently. In my opinion, 160 is just too low.

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Z-ya and I were just having this conversation, PM.

 

He's with you. I haven't bought into it... yet. Share your thoughts? (If this has already been hashed lemme know and I'll warm up the search engine).

 

I don't know of any previous threads so let'r rip. This is all my opinion but I believe that most engines operate more efficiently when the coolant is kept at a proper operating temperature. I read somewhere that a modern engine (L28 is not in this category) has optimal BFSC, thus better mileage and horsepower at the 195 to 200 degree range. I think it has something to do with cylinder sealing and oil temp. An example would be some of the new GM products. My wife's 3.4L V6 uses a 195 degree thermostat. The L28 wasn't designed to run at those temps. The problem is probably with piston side clearance and cylinder head cooling. This coupled with a 60's designed cooling system just doesn't make it practical to run the engine so close to over-temping especially if the cooling system isn't ideal. I think 180 is a fine compromise that still provides efficient combustion and adequate cooling in the cylinder head even for those summer track days.

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Regarding optimal cooling system temp for a highly modified NA L6 engine...

 

Jim Thompson at Sunbelt told me to run a 180 degree thermostat and keep the cooling system temp between 190 and 200 degrees for the best power and longevity. At the time Sunbelt was running the Speedvision World Challenge Mazda and BMW racing 6 cylinder engines around 210 degrees to get the most power out of those engines for a race. They ran them up to 225 degrees in qualifying trim.

 

I was never told why he preferred higher coolant temps.

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Regarding optimal cooling system temp for a highly modified NA L6 engine...

 

Jim Thompson at Sunbelt told me to run a 180 degree thermostat and keep the cooling system temp between 190 and 200 degrees for the best power and longevity. At the time Sunbelt was running the Speedvision World Challenge Mazda and BMW racing 6 cylinder engines around 210 degrees to get the most power out of those engines for a race. They ran them up to 225 degrees in qualifying trim.

 

I was never told why he preferred higher coolant temps.

 

This is pretty consistant with what I have heard (and experienced), too. I've generally noticed that I tend to run a leaner AFR (i.e. more complete burn) at 190 to 200 degF, and the engine just runs more smoothly there.

 

FWIW, I run a 195 degF thermostat - it's one of the high flow Stewart Components ones that has been drilled for some amount of bypass flow when cold. One side effect of this is that the engine often runs cooler than 195 - all of my 600+hp dyno pulls were done with the coolant temp right at 185 degF.

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This is pretty consistant with what I have heard (and experienced), too. I've generally noticed that I tend to run a leaner AFR (i.e. more complete burn) at 190 to 200 degF, and the engine just runs more smoothly there.

 

FWIW, I run a 195 degF thermostat - it's one of the high flow Stewart Components ones that has been drilled for some amount of bypass flow when cold. One side effect of this is that the engine often runs cooler than 195 - all of my 600+hp dyno pulls were done with the coolant temp right at 185 degF.

 

TimZ and JohnC. If I'm reading both your posts correctly you both have almost opposite results. JohnC ran a 180 thermostat with a coolant temp of 190-200. TimZ runs a 195 thermostat with 185 coolant temp. Assuming all cooling components are working properly, shouldn't the coolant temp on the gauge be no more than 5 degree higher than the thermostat rating?

 

Regarding optimal cooling system temp for a highly modified NA L6 engine...

 

Jim Thompson at Sunbelt told me to run a 180 degree thermostat and keep the cooling system temp between 190 and 200 degrees for the best power and longevity.

 

JohnC, Was this accomplished by delaying the electric fan from turning on until 190 or so?

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TimZ and JohnC. If I'm reading both your posts correctly you both have almost opposite results. JohnC ran a 180 thermostat with a coolant temp of 190-200. TimZ runs a 195 thermostat with 185 coolant temp. Assuming all cooling components are working properly, shouldn't the coolant temp on the gauge be no more than 5 degree higher than the thermostat rating?

 

For me it depends on the ambient temps, and the running conditions. Since I went back to the shrouded mechanical fan, on an 80 degF day I don't often seem to get to 195, unless I'm driving aggressively. I've only seen it go past 200 once or twice, and that was in the 'paddocks' at an autocroos between runs on a 90+ deg day.

 

The lower than setpoint temps for me appear to be attributable to the "drilled" thermostat.

 

Stewart Components

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