V8 heat confusion

[v8zed]

If they had an emoticon for pulling out your hair I would have used it.

71 240 w/355

sportsman 2 heads 64cc

silvolite 10cc domes .30 over

std. stroke

Holley 750 vac sec

running 81 on primary and yellow spring on vac sec

Doug Herbert Hydraulic roller

.567 lift 246 at .50

91 octane pump gas no ping

34* at 2800 rpm timing 10 at idle 950*

will idle all day at 185 degrees with fan comming on occasionally

runs at 95 mph for 18 min never over 180* in 85 * ambient would continue at this level NO overheating on highway

drive stop and go for fifteen minutes at not more thao 3000rpm and am runnign temps of 210 to 220.

Ran best of 12.97 at 111.9 in kansas city altitude no heating probs in 9 passes with idleing 10 to 15 min btwn runs

WTF

Any ideas?

Driving me nuttier than squirrel sh*t

Thanks,

Dennis

[TOMAHAWKZ]

POSSIBLY SOME AIR IN THE SYSTEM???

[v8zed]

I thought of that and to try to eliminate it I jacked the car up in front and fill it with water. I also have three 1/8 inch holes in the thermostat to try to keep out an embolism

Thanks for the thoughts,

Dennis

[Tim240z]

What radiator and fan? Is the fan shrouded?

[v8zed]

Griffin radiator with a Cadillac Fan full shroud with trap doors that open at highway speed. fan cools great at idle and highway speed. same exact setup was cooling the last engine at all speeds.Taurus fan switch turns on at 185* .

Last was early ls 1 (1970 ) with solid lifters,30-30 cam, torquer heads from world 67cc same pistons,crank, carb, fan, waterpump, shroud. Other engine had hooker shorties, am now using long tube headers from S&S bought from another list member.

I am wondering if I may have a bad lean spot in the carb at slow to medium rpm that could cause overheating but the plugs show a light chocolate brown .

[labrat]

I have the same issues, idle I'm fine, running hard I'm fine, highway fine. But in stop and go, the needle steadily runs towards the red. I know I have an air pocket in the system, and it's a b***h to get out. I've tried ramps, etc, to no avail. The only way I can get it good and full is to wing the throttle up to about 3500 rpm and wait for the air pocket to move to the radiator, then fill it and cap it before I let off.

 

Bill

[buZy]

Air Bubbles:?? How I got rid of mine in my 71 240z 327 was to install another radiator cap right in thermostat housing on the engine, Open the second cap and you can see the thermostat. Morso makes a kit for this and others do too. In short most of these V8 cars have an alum radiator mounted on the borderline of being to low with the radiator fill neck in realtionship the thermostat housing. Could cause an air bubble?? With two radiator caps, and two overfill lines now going to your catch can, you can fill up the motor and keep the upper radiator hose and manifold purged of air much better. Gives you a higher level to add more coolant as well keeping this upper hose now filled too. Every bit helps. CHECK your thermostat all the time. I have had problems with these even brand new. If the car sits for much time not being used they have a tendencey of sticking more but still working just with less precision. You could got to lower temp theromstat. Depends if you are racing or siting in traffic going no where. These V8 z-cars are very specializied. When building one many vital decisions about the car depends what speeds your running. A 170 mph car (maybe) will not idle all day in traffic typically and vice versa. You could solve that problem by updating to a Ferrari... hehe.

 

Low speeds..sounds like to me you need to get MORE AIR over the radiator. The engine has more air on the freeway and yet is making more hoarsepower, which means more heat. So I think your cooling displacement system is good you just need a fan system at low speeds.

It's all in the details...... Make sure your radiator doesnt have air leaks between the car body and radiator itself. I use closed cell foam for this. This forces more air through the raditor instead of going around it. ..... ""Cadillac Fan full shroud with trap doors that open at highway speed. fan cools great at idle and highway speed."" .....Your shroud that opens at freeway speed is killing your low speed air flow. Get rid of the trap door thingy. Your new, I would imagine stronger engine in now making more HP ...and heat... than your old one, on the average. Get more air over the radiator... at all times I say. The thermostat should mainly controll the temp not the air flow. An Open shroud with no air leaks or VERY FEW of them also helps a lot. This allows the fan to move the amount of air it was designed to move. And all through the raditor I might add.

Sure someone could tell me im wrong somwhere but I dont have any more coolong problems. Good luck and I hope you get it figured out and let us all know.

 

 

 

 

"Remember, Only YOU can stop terrorism."

[Pop N Wood]

You might also try adding a chin pan. The real early Z's suffered some overheating problems because turbulence underneath the car prevented a smooth flow of air through the radiator. Datsun's solution was to bolt a sheet metal pan between the frame rails directly behind the radiator. MSA still carries them.

 

Many have said engine timing can also affect overheating. So your ideas about tuning issues are not out of the question. Guess I would try what scumdog says, then the chin pan, then maybe install an oxygen sensor in the exhaust to help with tuning.

[MikeJTR]

Stealth Conversions (JTR) is currently making air bleed valves that can be installed in radiator hoses and in heater hoses, with sizes for hoses from 1/2" to 2". Cost is $25 each.

These parts should be on the JTRpublishing.com website within a few weeks.

[pparaska]

I have had too-hot (indicated by the temp gage) cooling system problems for a long time on several V8s, two different radiators and water pumps. I'm convinced that half the problem is the temp sensor (in the intake manifold, at a height near the top of the radiator) getting uncovered and reading the temperature of the steam. The gage can swing quickly as the attitude of the car changes, etc. At other times the system would boil over, so it really was getting hot. But it always seemed to have a lot of air in the system when I would check the level. I tried jacking it way up, revving the engine and adding water, but that is a real pain - I want a better method, and this thread points to two - BuZy's and JTRs.

 

I'm betting it's an air pocket in my case as well as the above cases. BuZy's idea for a radiator cap at the engine is interesting but I don't have room for that with my strut bar going right over the thermostat housing. I'm wondering if an Air Bleed in the radiator hose at it's highest point (just before the thermostat housing) or in the housing itself is a good thing to try.

 

MikeJTR- What does this air bleed you sell look like? Is it something with external threads that I could drill and tap some kind of pipe threaded hole in my AL thermostat housing and use the bleed there.

[grumpyvette]

first ID point out that 220F coolant should NOT be any cause for allarm in traffic style driving its almostr expected with a large V8 set up to produce high power when theres limited air flow thru the radiator at lower speeds, and also suggest that OIL does a great deal of the cooling of the hotter parts so installing a large OIL COOLER on the engine and a second one on the transmission(if its an auto trans) will go a long way towards cooling the engine and maintaining stabile temps

 

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRM%2D13318&N=700+4294854215+115&autoview=sku

 

you might want to install both a pull and push ellectric fan on the radiator if you don,t currently have both

 

just some info too think thru

 

the engines state of tune effects the heat generated, vacuum leaks tend to increase heat, octane used effects the heat, your ignition timing curve effects the heat

 

the type of coolant effects the rate heats transfered

 

the amount and type of oil effects the temp transfer rates

 

a larger oil filter, and larger capacity baffeled oil pan, tends to reduce temps due to exposing a larger surface area to the air flow, keeping the average oil temp in the pan lower:thumbsup:

 

anything that reduces airflow thru the radiator reduces its efficiency

 

the water pump and T-stat both effect the rate heats transfered, high flow water pumps can help

 

the electric fans work off a sensor and the temp they turn on at can be modified, larger or additional electrical fans can be added

 

on an auto trans car,the transmission fluid adds a good deal of heat to the radiator, adding a seperate ADDITIONAL trans cooler with a seperate ellectric fan,removes a good deal of the load from the radiator

 

oil in the engine flowing over parts absorbs and transfers heat , having a larger baffled oil pan hanging down in the airflow under the engine helps cool the engine

 

headers remove heat faster than stock exhaust manifolds

 

aftermarket aluminum radiators can be far more efficient

 

the dia. of the pullies your using does effect the coolant flow

 

running the correct T-stat can help cooling, generally the 180F-190F is the best compromize

 

http://www.digitalcorvettes.com/forums/showthread.php?t=81691

 

http://www.becool.com/

 

http://www.dewitts.com/pages/categoryresults.asp?catID=19

 

http://www.kevko.net/images/1090_full.gif

 

http://www.kevko.net/wetsump_chevy.htm

 

http://www.stefs.com/products/oilpans/circletrackwetsump.htm

 

http://www.radiatorbarn.com/?source=overture

 

engine oil needs to reach and stay at about 215F-240f to lube and clean correctly and burn off moisture

 

trans fluid I try to keep under 160F,surely below 180F ,

 

 

Ideally I try to keep engine coolant in the engine in the 190F-200F range but don,t get overly worried below 230F. BTW I run a 190F t-stat, temp ranges should be kept within these ranges or the wear and emmissions won,t give you the long engine and trans life and low emmission levels you expect , drop the coolant temps lower and you may gain a few hp but the wear tends to get worse as the fluids can,t opperate correctly, drop the oil temp below 211 F and acids can form in the oil (bad for bearings)

 

 

 

 

in an ideal world the coolant temp would stay in the 190F-200F range, install a 180F-or-190F t-stat and have the fans reprogramed to come on at about 185F-200F and youll see a marked stabilization of the coolant temp IF everythings functioning CORRECTLY

 

heres the fan control kits

 

185F

 

http://store.summitracing.com/partdetail.asp?part=SUM-890015

 

200F

 

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRF%2D30102&N=700+115&autoview=sku

 

this external trans cooler

 

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRM%2D12318&N=700+115&autoview=sku

 

personally I sellected the 190F T-stat 185F fan control , but IM seriously thinking of getting the 200F fan control simply because with my external trans cooler the engine oil temp seldom gets over 220F and it takes 215F to burn off all moisture in the oil.

 

on my corvette I felt the proper route was hot tranny fluid out to radiator then to the electric fan cooled trans cooler then back to the trans, simply because that maximized the temp drop to the trans AND I was not having ANY trouble cooling the engine, in fact the oil temp seldom exceeds 230F and takes a fairly long time to reach 215F.

I don,t know the trans fluid pressure but I did verify that my trans cooler was designed for transmision heat/pressure and was factory tested at 300PSI.

 

 

BTW if you route the other direction, IE seperate trans cooler first then to the radiator it makes for a significant reduction in coolant temp, and the fan on the seperate tranny fluid cooler runs constantly, but the engine coolant has a difficult time getting up to temp,(at least on my corvette) of reaching or allowing the oil temp in the engine to reach 215F LETS NOT GET INTO HOW I KNOW THAT ...

 

btw some comon areas people SCREW-UP

 

(1)

theres TWO differant types of water pumps, most serpentine belt water pumps are REVERSE ROTATION compared to the standard SBC water pumps and of course wount work correctly if they get installed in an application where they spin in the wrong dirrection

(2)

some head gaskets have significantly smaller than standard water flow passage holes that significantly restrict coolant flow rates to the heads, youll need to verify your useing the correct gaskets

(3)

your ignition timing has a huge effect on the engine temp, verify its close to correct, on both total timing and it advances smoothly as the rpms go up.

 

(4)never mix the older GREEN and newer ORANGE COOLANT (ANTI-FREEZE) they CAN in rare cases form a JELL over several months and clog a radiator

 

(5) air flow thru the radiator is critical, make darn sure theres no crud blocking the radiator fins, CLEAN IT FREQUENTLY with soapy water and a hose it takes surprizingly little mud or grass stuck in the fins to significantly raise temps and you won,t be the first guy to have a plastic bag or paper or leaves sucked up and blocking the air flow

 

(6) T-stats can go deffective, Id advise useing a known brand in a 180F-190f RANGE, and type , not the cheapest crap you can find

 

BTW I normally drill 8-10 equally spaced 1/8" holes in the flange of the corvetts t-stat all around the perimeter this allows coolant to flow even if the t-stat locks closed and prevents air trapped under the flange, :thumbsup: the picture below is of a semi similar mod on a differant cars T-stat, yes it takes longer to reach full temp, but Ive found no down side and it works better with this mod in my opinion

 

 

heres a couple chevy t-stats

Ive seen fewer of the upper design fail to function correctly

 

now IM sure some guys will say that defeats the T-stats purpose but it still works and theres a noticable increase in coolant flow at 190F when the t-stat opens so I feel its a no lost deal

[deja]

I have had too-hot (indicated by the temp gage) cooling system problems for a long time on several V8s, two different radiators and water pumps. I'm convinced that half the problem is the temp sensor (in the intake manifold, at a height near the top of the radiator) getting uncovered and reading the temperature of the steam. The gage can swing quickly as the attitude of the car changes, etc. At other times the system would boil over, so it really was getting hot. But it always seemed to have a lot of air in the system when I would check the level. I tried jacking it way up, revving the engine and adding water, but that is a real pain - I want a better method, and this thread points to two - BuZy's and JTRs.

 

I'm betting it's an air pocket in my case as well as the above cases. BuZy's idea for a radiator cap at the engine is interesting but I don't have room for that with my strut bar going right over the thermostat housing. I'm wondering if an Air Bleed in the radiator hose at it's highest point (just before the thermostat housing) or in the housing itself is a good thing to try.

 

MikeJTR- What does this air bleed you sell look like? Is it something with external threads that I could drill and tap some kind of pipe threaded hole in my AL thermostat housing and use the bleed there.

 

The LT1 engines have a bleeder on the thermostat housing. I don't know if the housing would fit your engine but you might be able to adapt the bleeder. The second one in the picture is on the inlet hose coming from the heater and the steam pipe from the intake.

 

[bjhines]

I have been tossing the idea of a "constant bleed" coolant system.

 

The idea is that the system continuously bleeds water/air from a high point in the system. The bled off fluid and air go into a "swirl tank" which drains the water back into the cooling system. The key is finding a suitable swirl-tank/air-separator and plumbing it from a higher-pressure area to a low-pressure area in the system. Other considerations include designing a system that will not overfill the swirl tank and will constantly bleed off the steam. re-condense it and return it to the system.

[dr_hunt]

IMHO heat is related to HP output of the engine, airflow across the rad, rad efficiency, water flow and system pressure.

 

Water temp is directly proportional to engine HP, the higher the hp the higher the water temp given a certain size rad with a given efficiency.

 

Water temp is directly proportional to airflow through the rad. Typically at speeds above 30mph, the fan is worthless.

 

Water temp is directly proportional to rad efficiency. Aluminum aftermarket rads are far superior to any stock rad.

 

Water flow is significant, too much or not enough. Too much flow and the resident time in the radiator isn't sufficient to shed heat. Too little and there isn't enough mass flow to transfer heat out of the engine.

 

System pressure keeps bubbles in check. If you have bubbles at 210, the the system pressure is too low. Always but always run the highest pressure rad cap you can find.

[Hey_Allen]

One other option that is mentioned in the JTR book was to just use the Moroso upper radiator hose radiator cap splice.

 

Putting it near the thermostat housing puts it high enough, in my car, that it's just a little higher than the top of the radiator.

 

I ended up putting a 20lb cap on the radiator, and a 16 or 18 on the upper radiator hose. I also capped off the lower bleed/overflow hose, as I want it to fill back into the system at the high point, getting rid of possible bubbles.

 

Another thing that I found helped prevent bubbles being trapped was to open the heater core all the way when purging the system, as I seemed to get some trapped air in that area if I didn't do that.

 

I suspect most of this was already common knowledge, but since I found other's talking about it, and it eventually worked for me, I suppose it can't hurt to restate it.

 

 

Thanks again to all those who originally suggested the solutions, as well!

[bjhines]

I have maintained a MkI Toyota MR2 into the 200,000 mile range. You wanna talk about a car with air in it's system and several "bleed" points.?

 

The Constant bleed system is used on all types of high performance cooling systems. I am waiting for TonyD to chime in on some oddball experience with this.

 

Dr. Hunt has made great points. I am still not convinced it is exactly that simple. I would love to get some feedback on the constant-bleed type of system if ANYONE has any experience.

 

I now own Pete P's engine(327 with 461 heads). Pete explained to me that he had cooling problems until the day he mounted the factory 327 waterpump. This was with a very expensive aftermarket pump that simply failed to function properly. I would love a better explanation of the problem but... It is my problem now.

[pparaska]

BJ - I didn't mean to say that the stock water pump totally fixed things. It was a strange intermittent problem I was having and the water pump change didn't really seem to fix it. I really believe that the problem I had with the 327 and the problem I have now is related to air in the system, as I've tried a 3rd water pump on the 406 now, an Edelbrock Vic Jr pump, and it acts the same as the Steward Stage 2 pump and the OE pump I've tried.

 

Glenn McCoy has a BMW 3 series radiator in his Z, with a Volvo closed system remote coolant tank and cap on the system, and it seems to not have the problems with air in the system. I don't think fixing this problem is a huge hassle as I think getting either an air bleed or a radiator cap with overflow outlet at the highest point is the way to fix it.

[bjhines]

stage one: A properly located radiator cap will get rid of big air pockets. If it is not the highest point then it simply will not function at all to remove air.

 

stage two: The addition of an old-school coolant reservior will keep you from having to refill every time you start it up. It also allows the normal heat cycling of the watermass to "intermittantly purge" the system as you drive.

 

stage two point one: The high pressure remote reserviors with the radiator caps on them are just a workaround the fact that the radiator is mounted low. Remember that the cap with the pressure-relief valve MUST BE THE HIGHEST POINT IN THE SYSTEM or it won't purge air at all. There is no functional difference between high pressure reserviors and the old-school overflow tanks. They just relocated the relief-valve/radiator-cap and pressurized the overflow tank.

 

stage 3: A constant bleed system continuously purges a small amount of fluid/steam from the higest point in the engine in the water jacket. The swirl tank returns condensed water back into the suction side of the water pump. There can be more than one purge point in the system. You can bleed off ports on the heads near the exhaust valves to constantly remove steam bubbles from the system. The main purge points are usually on the hot side of the thermostat with the addition of another purge point in the top of the thermostat housing. The purge point in the top of the thermostat housing is ported at the bottom of the tank to allow water to flow back instead of sucking in air. The swirl tank also functions as the reservior.

[bjhines]

I might add that the inline radiator caps are less than ideal. The problem comes from the fact that there is no dome in the inline housing. The dome catches air and holds it in one place. The filler neck and cap on the radiators act like a dome to catch air and keep it there until it is purged. another good place is the dome on the thermostat housing. Tap it and provide a bleeder there to purge purge air that it has trapped.

[Pop N Wood]

stage 3: A constant bleed system continuously purges a small amount of fluid/steam from the higest point in the engine in the water jacket. The swirl tank returns condensed water back into the suction side of the water pump.

 

Boy, I don't understand that statement at all. Why do you have steam in your cooling system?

 

I can see some localized boiling at hot spots and or points of poor flow inside the engine. But by the time the water gets to the thermostat housing there had better be no steam in the stream. Even if there was, the best solution to get rid of steam is to cool it. At which point I don't see the utility of putting in a separate vent. Just run it through the radiator.

 

And unless you vent it to the atmosphere your "constant bleed" system is not going to do anything to remove air.

 

Not flaming, just initiating a discussion.