Overheating

[Lextreme II]

Hey Gang,

Not sure why but my car is over heating. I took my mechanical fan out and put in one 16" fan in along with two smaller fans outside. Do u my electrical supply shortage. I am only running one 16" fan and my car is over heating. I took my thermostats out days ago and problem still here.

I would like to know how do i know if the radiator or the water is in good working order. Is it possible the water pump is bad. What are the signs and symptoms of the water pump being bad?

Both the radiator and water pump is pretty new. What could be the problem. Not enough cooling or too much boost?

 

[jpi1]

What is the temp of your upper and lower radiator? We've seen people have problem after removing the stock fan. Make sure the coolant flowing through the system.
JP Importz

 

[Muzza_NZ]

Lex,
its probably a combination of all of the above.
You say water in the radiator, what concentration of coolant to water are you using? 50/50 is quite good.

There really isn't much to the water pump, even if it leaks it will still pump water.

The if you take the thermostat out, the water can just short circuit the radiator and actually make the problem worse - check if it works by putting it in almost boiling water, you should see the bypass shut off and the main outlet centre open.

Final thing, is your fan actually coming on? what temperature are you turning it on at??

hope that helps,

Muzz

 

[Lextreme II]

My 16" fan is always on.... So its a bad idea to remove the thermostats?

 

[chrisman]

is it boiling the water over very quickly? is it possible a head gasket is not sealing well? what kind of head gaskets did you use?

 

[chrisman]

hi lex, i just read in another thread that you are using copper head gaskets.. i have had problems with them in the past.. i think they are great--but should only be used for race engines/engines that get taken apart often.. i have had much better luck with OEM gaskets.-especially the toyta ones... i think you may have gone to the copper to use a thick gasket to drop the compression.. i would only use cooper gaskets if i O ringed the block or head..

i dont want to scare you with all of this, but i would take a good look to make sure you are not having a gasket sealing prob..

 

[Lextreme II]

I think JPI was right. I was filling my coolant via the reservior. I think this method will create air bubbles and get trap in the engine. I need to drain the coolant and fill it via the 17 mm bolt on top of the radiator inlet.

I had the copper gaskets for two years now, but no such problem existed.

 

[Muzza_NZ]

Hi Lex,
I see, you meant thermoswitches not thermostat per say. If your fans always on, it just ain't doing the business.

Also, you don't need to fill the radiator from the bolt on top of the thermostat, just bleed it from there.

Are you actually losing water? Has it only started overheating since you removed the two auxiliary fans, or they still sitting there idle? They won't be helping the cooling air if they're in the way.

Muzz

 

[Zuffen]

Lex,

Part of the problem is boost.

As you increase the flow of air into the engine you also add more fuel which increases the amount of heat the engine produces. I know you will already know that little gem, but remember your radiator was only built to service an engine with 251cc Injectors and you're running 550cc injectors.

Simple maths will tell you the radiator has to work twice as hard.

Have you tried driving with the heater on to see if this helps with the overheating. If it does it's indicative the radiator is too small, partially blocked internally or has external restrictions.

Remember the cool air that used to flow thru your radiator matrix is now the hot air off you intercooler. You're asking an awfull lot from the stock radiator.

 

[cribbj]

Rod hit the nail on the head; you've increased the engine's output, but done nothing for the cooling system, and at least as much horsepower is going into the cooling system as there is out the crankshaft. To help your radiator and cooling system do the best they can, clean up your cooling system with a good flush, or have a garage that has a flushing machine, and uses BG products do the job. Then refill the system using only distilled water, and just enough coolant to keep the car from freezing in the winter (I think in LA this probably means little or no coolant), then put in a pint of Redline Water Wetter, or similar product that reduces the surface tension of the water, and finally buy a higher pressure radiator cap, because with less coolant in the mix, it'll want to boil sooner.

Why minimal coolant? Plain water is the best heat transfer fluid available. Its specific heat capacity is higher than all other commonly available cooling fluids. Anything you add to water will only take away from the solution's ability to carry more heat away. Why distilled water? Minerals in tap water will build up in the engine and insulate the metal passages and reduce the heat transfer. Tap water also promotes accelerated bimetallic corrosion if its pH isn't neutral.

Why Water Wetter? If you can reduce the surface tension of the water, it will have better contact with the metal surfaces you're trying to carry heat away from, and the heat transfer will be more efficient. Redline Water Wetter also has corrosion inhibitors added that will help these all aluminum engines and their cooling systems. (No, I am not a dealer for Redline).

Have a look at the Supra FAQ for more info on cooling:
http://www.mkiv.com/faq/faqtt.html#enginecooling5

John

 

[Lextreme II]

John and others, thank you very much. I put most plain water into the radiator. Cali is pretty ok temp and we never see snow or colder then 32F. I will have to temporary change the fluids and drive it to a local radiator shop for the service.

 

[Lextreme II]

Problem fixed!

I drained the radiator via the plug under the radiator. After all fluid come out, i release the 17 mm nut on top of the engine. I run a fresh a garden hose into the 17mm hole and let it fill. When i see full stream of water come out under the radiator plug, then i put back the plug and start up the car. I continue to fill the with water and combo with radiator coolant to top if off. I also fill up my reservior with coolant.

Right i now i run my car for 30 minutes, the tempt is only 1/16 of the scale. Thank you gentleman.

 

[jpi1]

Problem fixed!

I drained the radiator via the plug under the radiator. After all fluid come out, i release the 17 mm nut on top of the engine. I run a fresh a garden hose into the 17mm hole and let it fill. When i see full stream of water come out under the radiator plug, then i put back the plug and start up the car. I continue to fill the with water and combo with radiator coolant to top if off. I also fill up my reservior with coolant.

Right i now i run my car for 30 minutes, the tempt is only 1/16 of the scale. Thank you gentleman.

Always always open the 17mm nut and fill up coolant through there. I'm glad it work out for you David! Now put that thing on the Dyno please. We'd like to see some hard numbers.
JP Importz

 

[jpi1]

hi lex, i just read in another thread that you are using copper head gaskets.. i have had problems with them in the past.. i think they are great--but should only be used for race engines/engines that get taken apart often.. i have had much better luck with OEM gaskets.-especially the toyta ones... i think you may have gone to the copper to use a thick gasket to drop the compression.. i would only use cooper gaskets if i O ringed the block or head..

i dont want to scare you with all of this, but i would take a good look to make sure you are not having a gasket sealing prob..

Why would cooper headgasket is bad? It depends on how you torque the head down.
JP Importz

 

[chrisman]

i didnt say they were bad, but that i have had problems with them over time.. remember that copper is pretty soft, but will harden over time.. one of the major plus's of the copper gaskets is that you can re use them.. but you will need to soften them up.. torque-ing the head down properly is important..
years ago, we used to spray down copper gaskets with aluminum paint believe it or not.. this was another way for us to help seal everything up..
but i would only use a copper gasket if i oringed the block or head..--and only in an application where i would be taking the head off often..
believe me when i say that if they were superior to OEM, the manufacturers would only be using only copper head gaskets.. i have yet to see an oem use a copper head gasket..

 

[Lextreme II]

Found the problem. My water pump seal was leaking radiator fluid and i was low on water and over heat. Now it will be a pain to change the water pump.

 

[Lextreme II]

Ok.... water pump changed, radiator changed (OEM)... still over heat during aggressive driving. I will try Water Wetter this week and see..... I guess time for a Fluidyne soon.....

 

[Miles B]

I don't know.. Ethan Banks ran a stock radiator in his 980+rwhp SC300 and told me it didn't overheat. If the LS has a similarly sized radiator, I would look at other things being the problem. Airflow blockages, new fans not doing the same job the old one did etc.

 

[Lextreme II]

I was running two 16" fans but now only one because of the space occupied by the turbo. For some reasons, the new radiator doesnt cool as well as the older one. I am using pure water right now.....

 

[turboandrew]

I would go back to the stock fan if you can, unless you can confirm your electric fan will flow the same amount of air (they rarely do). I've seen this on Supras all the time.