I am a new vette owner and have a problem already. I replaced the overflow jug on my 94. The fluid is boiling at 212 degrees. The fans only come on when the a/c is on. Is that normal?? Is is supposed to run that hot? Any help is appreicated.

 

One thing I can tell you is that Vettes seem to be very hot running cars. I would check and make sure your thermostat is working and you could always stick a 190 or 165 degree thermo in the car.

 

When you say "boiling" do you mean boiling overthe top of the recovery bottle or actually boiling?

 

with the cap off the water was gurgling and spewing up.

 

I have an 85 vette and it has gottin up to 230, but it had never boil over the top.

 

my 87 vette has the 160 thermostat and yet the fans do not kick on until 230 degrees and shut off at 200 degrees. I talk to a friend of mine that used to work for the chevrolet dealer as a mechanic on corvettes and he said that the TPI/LT series engines were designed to run hotter than most around 200-230 degrees. I was very concerend when my fans did not kick on until 230 degrees, I thought my fan motors were bad also.

hope that this info helps

Greg

 

When you say it boils with the cap off, is that the overflow reservoir cap or the radiator cap? Because it will boil at 212 with the radiator cap off.

I would check your radiator cap, it may be failing. And check the water/coolant ratio.

 

I think the LT1 is calibrated to run hotter than the L98.I think it has something to do with emissions.If you think it's running hot,put a 165 or 180 degree stat,and every now and then turn the a/c on.The fans will kick on and keep your temps at a more reasonable level.

 

Heres some info that might help you.



Normal operating ranges,
Oil-anywhere between 210-230
Coolant-should settle at about 15-20F below the oil temperature

LT1 cars will run just a bit warmer than L98s, but the same ranges apply.

Main fan on/off:
Varies just a bit in exact temperature over the years, but it should come on anywhere between 225-228F (coolant), I say that because the in-car gauge is rarely so accurate for you to say its coming on exactly when the manual says it should.
The main fan will also cycle with the A/C running.
Aux fan (if you have it)-in front of your radiator and condensor, and it should come on just above your main fan temperature, say 228F, though in 85-86 it came on at 238F.

Stock Thermostats-
L98-195F (coolant)
LT1-180F (coolant)

Once the engine starts, your car will proceed upwards to the thermostat opening temperature, at which point it should hold steady as the stat cycles open and closed. At that time, the oil temperature will catch up with the coolant and usually passes it. This drags the coolant temp up towards the fan setting. Generally it'll settle at about 15-20F difference between the two.

Danger zone-if you have aluminum heads, do NOT allow the coolant to reach 250-260+, or you're risking a head gasket. That applies to both engines. A dino oil engine can handle oil temps ~250 for short durations, but above this the oil breaks down and you need to change it sooner than usual. Synthetics can withstand ~300F.

Things to do if you suspect the engine is overheating:

1.Check to see if the thermostat is indeed working. Car temperature should stabilize momentarily at the thermostat opening temperature. If it doesnt, replace it.

2. Check to see if the fans are working. Let the car idle up to fan temperature and make sure they come on when they should. Try running the A/C to see the fan itself actually works at all, it should come on within a few minutes of running. Main fan relay is on the radiator shroud starting in '88, and earlier years have it just below the Master Cylinder on the wheel-well.

3. Check to make sure the WP is not weeping. There are weepholes in the WP that will leak when its bad. Its hard to diagnose otherwise.

4. Remove air bubbles in the system, and check for pressure leaks. Old caps lose pressure and should be replaced every 2-3 years when you should flush your system. Also check for small leaks in the hose between radiator and overflow/surge tank and make sure all hoses are tightly clamped. Some leaks dont happen until the engine is hot, you must be sure.

To burp the motor-for the L98 let the engine warm up with the rad. cap off, until the thermostat is open fully. While you are doing this, hold the engine at 2000rpm or the coolant will just bubble out. You can do it by yourself, but its best to have another person inside the car. Once the stat is open and the throttle is pressed, the coolant level will drop....fill it up and replace the cap. It may take 2 tries to get all of the air out. LT1 systems use a bleed screw next to the TB to allow air to escape.

5. Clean the space between radiator and condensor. The C4 is a vacuum cleaner and sucks things up through the nose, because the intake actually breathes in air after its passed through the radiator and condensor (not through the little air gaps in the hood or shroud). Debris passes above the condensor and settles in the space between it and the radiator. Once this is clogged the temps will end up about 10-15F higher. Dirt and grime will also cling to the fins in the radiator, and must be removed.

See the Techtip on doing this, you must remove the shroud (not as hard as it looks) to suck the debris out with a shop-vac. You should also remove the radiator and use a screwdriver to clean out the fins and straighten each one before putting it back in.

6. Flush the system-old coolant becomes acidic and eats away at rubber internals and the radiator itself, causing leaks to form. You should flush the system once every 2-3 years and replace with 50/50 coolant/distilled water mixture. You MUST use distilled water, regular tap has some of those acidic/ionic impurities aforementioned.



Does the car still overheat?:
If you see any plumes of white smoke in normal operation, once the car is hot (ignore any light wisps of smoke on startup, it may just be condensation in the exhaust, especially when it gets cold at night), then you have a head gasket failure. If it doesnt do that and still continues to rise, then theres either a pressure leak in the system that you havent found or it could still be a head gasket. It doesnt have to look like a shuttle launch, but usually it does.

If the car is just running too hot for your tastes the only permanent fixes are a combination of the following,

1. Reset the fan temperature in the ECM, either from a chip or laptop tune for PCM modules. 195-210 should be fine.

2. Change the thermostat to a lower temperature, this applies more to L98s than LT1s in my opinion. I use a 160, and theres another discussion of that whole debate on another page here.

3. Add a larger radiator. DeWitts, Griffin, BeCool, Davis, etc. These will not help idle temperatures so much, but once you get moving the temps drop fast. I now see a 30F difference between oil and coolant with the DeWitts on the highway, even on hot days it keeps the coolant low (mine was 180F in 100F outside heat at 70mph on the highway).

4. Better water pump-Stewart, FlowKooler, etc. These affect idle temperature rises more than anything else, since they pull coolant in and push it out faster than the stock pump at idle. The car will still proceed upwards in temperature t idle, but a bit slower.