i have a 2000 corvette, with a supercharger, heads cam package, the problem i have is, at the track or on the street when i get on it and get into the high rpm range the coolant starts over flowing out of its reservoir and the car gets hot. I have been told that i might need a new thermostat, the one i have on the car is the factory one, any suggestions on why this is happening. Also when i first start the car it starts out running hot but if i drive it for about 5-6 minutes the temp goes back to normal,

 

Sounds like a head gasket issue putting pressure back into the system. Do you smell coolant at all anytime.

 

I only smelll it when it spills but once it dries up its ok

 

I have heard of thermostats just sticking. The way you describe the car heating up and running hot until you've driven around for a bit would indicate to me this may be the problem. Thermostats are cheap, give it a try.
Of course I assume there is no white smoke coming out the tailpipes, during start up or other wise.

 

Thermostats are cheap and easy to install. Your problem is probably related to something else (like what Doug mentioned), but if you're running a stock thermostat and you're tracking the car, swapping the thermostat to a 160 or 170 can only help you out.

 

Is my first thought as well. If you get into it and the head gaskets have lost the seal, then your coolant system will get pressurized.

Question that I have is that the stock C5 system is a sealed system with no overflow vent to the outside environment. Pressuring the system might bulge the plastic surge tank or created a break in the tank aor one of the hose connections.

If you see coolant on the ground after you park it, and you have the stock C5 cooling system...the coolant is coming from somewhere else because there is no pressurized cap...whether it be broken hose, craced rad/tank, or between the head and block from a blown head gaskets.

 

An easy way to tell would be to look at the coolant temp when it overflows. I remember with my supercharger, after I'd break a belt, I'd get coolant all over the place because the water pump would stop spinning and my coolant would hit 270-280 real fast (which was about where it seemed to overflow out of the reservoir). The cap will definitely let coolant pass through somehow when the coolant gets hot.

 

Yes it's only plastic and it could possibly bulge the tank as I mentioned and let the cap leak. But you indicated that your belt was broken and that your water pump was not operating and the engine temps were basically at max and therefore you were losing coolant.

The thing I read in his post is a specific statement...when he gets into it and hits the high rpms ranges (being boosted this is a pretty good sign that the system is being pressurized). THEN the cars gets hot. I didn't see belt slipping off and temps at 270* causing overheating.

A thermostat failing to open would cause the system to overheat with normal driving. Not dependant on getting into it (implying boost) at higher rpms. I based my response on the specific that he was getting into it and at higher rpms...then the car overheats and coolant is escaping.

The way the system is designed on the C5 is for coolant not to escape out of the system..nice and Environmentally friendly...don't want Dexcool being licked up by somebody's dog or getting washed down a stormwater drain. So if the only time he is overheating after getting into boost at higher rpms, and it is causing coolant to leak out. It is coming out of someplace that it is not supposed to.

Check your dipstick after a couple of runs and see if the oil looks like a milkshake...water intrusion..this is another way.

Look for stains on the side of the block where the heads meet the block.

By some dye at your local automotive parts store and put it in the cooling system. If it is getting past the gaskets into the cylinders and down in the oil...the dye will be present when you check your oil.

Do a compression test to see if you have any pressure drop on two cylinders right next to each other.

By a pump (may not be possible with stock tank cap) and pump up your coolant system and see if any coolant squirts out from anywhere....heads, hoses, cap, waterpump, rad tank, etc..

 

by the way this is a built engine, we have a new b cool radiator, and the first time this happened was on the dyno with the hood up, the coolant came bubbling out from under the cap, i think we may try the new thermostat first,

 

nope no white smoke

 

I run a BeCool radiator as well..in fact I just put one in over this last series of improvements. Maybe you did not put the fluids in correctly, nevertheless if the thermo wasn't opening..it would have just got hot period. I alway's fill the tank and start the vehicle, watch for the thermo to open (heater running) then as the fluid level drops...add more fluid.

On older SBC the proper way to refill the motor is to disconnect one of the vent lines to let all the air out of the system as your were filling, or if the thermo was on top to fill the block and put the thermo in place. If the block was drained the is only air behind the thermo..this can lead to a thermo not opening..but if the fluid on top gets hot enough it should open..

you can alway's do the old trick..take your thermo out and boil it...watch what happens.

I provided you the easiest method for determining a blown head gasket. Check the dipstick after a few runs and see if you have water in it. That is easier than even pulling the thermo and boiling it.