95 Chevy Caprice 5.7 Overheating

Hey all...I've got a 95 Chevy Caprice Wagon 5.7 ls1. Running Straight water because it's a racecar, Radiator fans work off a toggle switch, so they are always on, No thermostat, and water Seems to flow properly out of and into the water pump. But the car is still overheating. What other possible causes could be for this to happen?

It's an LT1, sorry. Also has the exhaust cut off.

With no thermostat the water will not move through the pump properly, ever notice the stock pump has two poppets to it?? Want it to run cooler use a proper 160 stat, want to delay warmup further drill some holes in the upper piece.

So without a thermostat the car is going to overheat?? I don't really understand how that could be possible. The water should be flowing constantly through the waterpump keeping the vehicle cooler. I've got an Enduro Ford Escort without a Thermostat and it does not overheat.

So without a thermostat the car is going to overheat?? I don't really understand how that could be possible. The water should be flowing constantly through the waterpump keeping the vehicle cooler. I've got an Enduro Ford Escort without a Thermostat and it does not overheat.

this engine has reverse cooling flow....from the heads down...the thermostat is also specific to this vehicle,,using the wrong one or no thermostat you will not get the coolant to flow thru the engine properly..

many have learned the hard way...installing the wrong application thermostat...

also you will need to bleed this coolant system...a few times to get the air out..

running with 50% antifreeze will give the best cooling and protect componets from damage....but its your problem..good luck

running with 50% antifreeze will give the best cooling and protect componets from damage....but its your problem..good luck


LOL...thanks!! I can't run antifreeze at all. The racetrack does not allow it. But...I think I understand then...that it's possible that air is being trapped in the motor from not having the thermo there correct? The water is passing to quickly through the water pump that it's not allowing to go through the engine properly?

LOL...thanks!! I can't run antifreeze at all. The racetrack does not allow it. But...I think I understand then...that it's possible that air is being trapped in the motor from not having the thermo there correct? The water is passing to quickly through the water pump that it's not allowing to go through the engine properly?

Look, jcat is an imbecile who read a book a couple decades ago and thinks that makes him an expert. He posts a LOT of grossly outdated or just plain wrong information on a daily basis.

straight water will actually cool better than mix, look into the thermal transfer properties of water vs. ethylene glycol. http://www.crownsolutions.com/lib/crown-solutions/EFD7i8WKSQONn9ZC8Vupyuud.pdf

You need to get a clue too. Did your Escort have an LT1 waterpump on it?? Guessing NOT. So exactly how is it that that experiance applies here??

The LT1 waterpump has two circuits inside it, by running no stat you no longer keep them divided or controlled. It is designed to recirculate a little hot water in with the cold comming from the radiator to avaoid thermal shock. I bet with that you did by not leaving the thermostat there to control such is now it is recirculating too much of the hot water back into the engine.

I know I probably hurt some feelings but I HATE stupid people contradicting good advise.

In addition to installing the T-stat, you may also want to look into one of the Water Wetter products on the market that claim to reduce cooling system temps.
Although since you cannot use antifreeze, not sure if these products would be allowable either.

LOL...thanks!! I can't run antifreeze at all. The racetrack does not allow it. But...I think I understand then...that it's possible that air is being trapped in the motor from not having the thermo there correct? The water is passing to quickly through the water pump that it's not allowing to go through the engine properly?

since you are operating where coolant is prohibited,,,,you should flush your engine often,,,use pure distilled water...with no coolant the internal engine surfaces get coated with slime/corrosion deposits...perhaps there is a product the racers use to keep your engine from this,,, that is permitted..

after installing a thermostat bleed several times to get the air out..

Thanks for all your input to this issue. I found that the condensor was blocking the airflow to the radiator and the heater core was allowing air into the system. I eliminated the heater core and the condensor, put a new thermostat in, and bled the system several times. So far the car has not overheated.

[quote=Purestock;6021131]. I found that the condensor was blocking the airflow to the radiator /quote]

Since this is a race car, I would think you would have removed all the ac components to reduce weight.

Glad you found the problem..

I was trying to get the car to run right before I started the dismantling process. So that is what I am doing now.

I have AC in my car yet, pretty potent motor, no overheating, no cooling upgrades, heck I actually broke down and tried an electric pump which is a DOWNGRADE but worth time at the track and no overheating, though in a pass at the strip where the mechanical would allow a 2 degree rise the electric allows a 10 degree. Anyone tells you an electric pump is an upgrade ignore their input, they are too stupid to understand how things work. The electrics free up power to the wheels by using LESS power to do LESS work, that work being water flow.

You have an airdam on the car? They are important to proper airflow.

Not only do I have AC in the car but the radiator is out of an old copcar I bought the front clip off of. No special additives or anything, car is fine at over 100f outside even with the AC on.

No special additives or anything, car is fine at over 100f outside even with the AC on.

That's how it should work.........

Bought a 95 caprice 5.7, battery would not hold a charge, changed alternator, battery post and battery, found it was charging wire was cut inside harness, ran new wire to fuse box under hood, instrument panel and digital dash did not work, changed cluster and fixed it. Car keeps overheating so checked radiator and it was good, changed water pump and.thermostat, bled block several times on several different days, but still keeps overheating, no miss in motor, no liquids mixing, no smoke from car so not a head gasket.Cars runs and sounds great, but keeps overheating aftef only about 5 minutes of running and both fans work. This thing is drriving me crazy:screwy::runaround:, please help.

Bought a 95 caprice 5.7, battery would not hold a charge, changed alternator, battery post and battery, found it was charging wire was cut inside harness, ran new wire to fuse box under hood, instrument panel and digital dash did not work, changed cluster and fixed it. Car keeps overheating so checked radiator and it was good, changed water pump and.thermostat, bled block several times on several different days, but still keeps overheating, no miss in motor, no liquids mixing, no smoke from car so not a head gasket.Cars runs and sounds great, but keeps overheating aftef only about 5 minutes of running and both fans work. This thing is driving me crazy:screwy::runaround:, please help.

my experience with what your already done is too much pressure or NO pressure. squeeze the radiator hose see if its with pressure. loosen cap see if it is with pressure.

the other issue would be mixing coolants your 95 should have the green coolant . in 1996 GM changed to Dexcool gm approved coolant. If someone mixed these it will get gooped up..

also removal of the KS both drains the block then you flush out thru the T stat bore until clear . then using a water hose flush out the heater core by removal of the hoses at the block not firewall. until clear and good flow then blow out.

do not use drinking water in these engines only use distilled even with the other type coolants .. 50% mix I do not use .. tested it and it is not 50% but less also very expensive distilled is 1 buck a gallon not 6 bucks.

If you installed the thermostat backwards they will over heat before they open.