abraham

Ok so I have a 97 with a Agastino(are) installed head and cam. Along with headers, exhaust etc... A few years after the install the car started running hot and eventually overheating. Seemed to get worse every year. Now I can only drive it for about an hour and it will overheat. I'm going by memory hear since I have not dealt with this issue in years. I am trying to sell and would like to at least find the problem or fix it first. There is a cooler tstat in it although I dont know the temp. Radiator is dirty and cleaning it helps but does not solve. Not loosing fluid or getting anything in my engine compartment so I dont think its a head gasket though cant be sure. Closest place I trust to look at my car(vector racing) is to far to drive the car. Was hoping some one could walk me through diagnosing the problem. Ive heard head gasket, temp sensor(which I had no idea of till recantly) Water pump(dont know how to check) air in the line(seems like a bigger problem but what do I know). The fans do work. I am a mechanical contractor and good with the tools but dont do alot of car wrenching. Specially diag. Any suggestions and how to check the issue? Any help appreciated.

v6turbo87

First off don't assume anything. Do a compression check to rule out a head gasket issue.
A cheap thing to do it replace the thermostat as it could be stuck shut. When you pull the old one out it will have the temp rating stamped on it. A lower temp thermostat does nothing to help the engine run cooler it just sets the minimum temp the coolant gets to.
When was the last time the coolant was drained and flushed? The radiator could be clogged internally and need to be replaced. When you say it has been cleaned do you mean the outside of it? They can get clogged with debris and cuts down on the air flow through the fins--the fans shut off at 35mph.
BTW....define the overheating? Is it going into the red after an hour or is it just running hot?
We all think our beloved Corvettes are very special, but a problem like this can be diagnosed by any competent repair shop.

abraham

It will overheat totally. I did change but not flush the coolant several times over the last few years. I cleaned the outside several times as well but never pulled the radiator. I have no tools so compression tests and such are not feasible. But your right, I could just take it anywhere for a compression test. Thanks for getting that through my head

mmartinez

Do a search on this forum for burping the cooling system, it will help if you do have air trapped in the cooling system. The main part of the cooling system is of course the radiator, you might want to pull it and take it to a radiator shop to ensure that its not clogged internally.

Smoken1

What PSI is your cap say on it 15 or 18 PSI? If it is the original 15 psi I would replace it

Robrote

When you said you cleaned the outside, did you remove the 4 10mm bolts on the rad support, remove the air bridge and look between the radiator and condenser? If not, you need to check there.

Ceedub53

Your AC condenser could also be clogged up with road debris. It sits in front of the radiator. A blocked AC condenser will block air flow to the radiator. Pull the upper radiator support along with the intake and use a flashlight to check out the condenser (in front) and the radiator (behind it). Clean away any debris that could be clogged in there.

abraham

Yes I removed the shroud and cleaned many o times. even used some ac cleaner foam stuff. It is dirty currently but this has never solved the problem, only helps a little. I was going to start by pulling and cleaning(and now taking to a radiator shop). Once I do that I have a disabled car in my driveway. With little tools and only an outside driveway to work in I may take it to a guy I found out about that works on Vettes. A guy named rick parks here in MI. I will read up on burping the system. I have never done that and only filled up the reservoir. Never back filled the system when refilling and its been refilled about a dozen times. Pretty much overflows everytime I pull into the driveway. Which is about once a year these days. It is the original radiator from 97. Never been changed. I have not looked but will. Thanks for the replies. I think I will take it to Rick in case the radiator is not all it is.

abraham

surge tank is full but I still get a low coolant message.

abraham

I actually did a leak down/block test with the test liquid and it did not turn yellow. However I could not get it to turn yellow even putting it right next to the exhaust pipe of several cars. So inconclusive I guess. Bad test kit? Who knows. I'm going to try bleeding air out of the front heads as I see in several threads. And yes I do have the 15 psi cap. Guess I'll replace that for what its worth.

TorqueWinsRaces

Here's the deal with that. I used to clean my radiator about every 6 months because I live in an agricultural area with a lot of leaves and dirt roads and chicken feathers and stuff that gets in between that condenser and radiator. My car would always get hot regardless. I just kinda thought it was crappy factory cooling system; I was wrong. I finally broke down and bought a Dewitt's work-of-art radiator. When I took my radiator out, I immediately saw the problem. I could not see any light through the radiator! The fins were jam packed with dirt. You would not believe the pile of dirt I blew out of the fins. I have the radiator sitting in the DeWitt's box and I'll bet anything that it would work just fine if I were to reinstall it.

That's my story, and I will bet there are a lot of hot-running C5's out there that have this problem.

abraham

Mines not even drive able unless you are just running up to the corner store for 10 minutes. It will just max out and stop running. And even when I bring it back while its only at 220-230 it will still boil over out of the cap. I am on my way to get a 18psi cap in a few. The one I have now is 15 psi. Hopefully that will help. I have not wanted to risk it getting to redline again so who knows maybe it is just running hot these days and just redlined that one day. Dont want to risk it so I just drive it for short rides but like I said it always boils over when I get home even if at fairly normal temps. I tried to burp the system by removing the hose near where it enters the heads like I have read, to fill up till coolant comes out. Well coolant came out as soon as I removed the line.
also while squeezing the lower large hose I swear when releasing it, it sounds like air is getting sucked in somewhere in the radiator. I have no leaks though. Any thoughts on that matter, I could be wrong but it does sound that way.

454z06

The cap isn't the issue if its heating up that quick. I would say blocked radiator, bad water pump or t-stat.
have you noticed if and when the fans turn on?
2nd fan on?
Starting out with the car cold, turn the you heat on full hot and watch your temp gauge. What's the gauge at when your heat starts getting warm and when it's close to full temp?
the radiator and heater core are probably blocked up from all the old head gasket material that fell into the block when they did the h/c package.

Smoken1

The stock head gaskets are metal so there is nothing to fall into the block.

abraham

felt like it started getting warm around 105-110 and was full heat (I think, its hot out) at around 130. Could have been getting warmer. It dont redline in 10 minutes but get close so Ill hurry home or whatever and when I park the car it will spill out the cap. Hard to say how far it will go cuz I dont want to get stranded on the side of the road and have to wait a half hr for the car to cool off. I had it idling for abut a half hr yesterday and it was staying at around 220. Going to let it idle for awhile, check that both fans are working(I know at least one is cuz I can hear it stopping when I turn the car off). See if it will over heat just idiling. Just noticed the new cap clicks on like a gas cap. My old one never did that.

Robrote

That sounds like a plugged rad (either inside or out) or a bad water pump. You have a lack of flow. Either coolant or air. Back in the day, it impellers on water pumps could become dislodged on the shaft. They looked like they turned normal but the impeller didn't spin. Not sure of the LS design if that could be a potential problem. Obviously the T-stat is an easy replacement. Good time to make sure there isn't any 'mud' in the bottom of the radiator causing the coolant not to flow. I'll be anxious to hear what the problem is.

abraham

Well I have had the car idling for a half hour now and I'm sitting at 198 coolant temp and 201 oil temp. This is after attempting to burp but dont think it needed it. squeezing the hoses and replacing the cap from 15psi to 18psi. I walked inside for a second and when I came out both fans were on at 187* I assume my tuner did that 15 years ago. I assume that would rule out water pump, stat, and clogged radiator?? I'm going from memory from about 14 years ago when I first had the issue but I remember that it seemed that the oil temp would pass the coolant and then the coolant would catch up and so on. Sitting pretty right now at idle. Going to pick up my daughter from school in another vehicle then come back and take the vette for a cruise around the block a few times and see what happens. Thanks for all the help so far.

abraham

few minutes later oil is at 205 and coolant now rising to 199. Not sure if this is normal but it seems like the coolant is chasing the oil temp. Wish I did not have to leave now but will retry in 45 minutes or so and report back.

Smoken1

Let's hope the cap was the problem..

abraham

So after doing the above and probably the culprit was CHANGING THE SURGE TANK CAP!! from my 15psi to an 18psi. (unless it was undoing the t fitting right by the head to bleed out air like I have read in other forums but I had coolant running out as soon as I took off the fitting) not sure if the pressure makes a difference or if my cap was bunk but I have just drove my vette longer that I have since about 2003 and its running oil temps at 235 and coolant at 225. Before it would have redlned in about a half an hr. This is in about 75 degree temps so we shall see but looks promising. Cant believe that could have been the issue all this time. We shall see though cuz its onlyl 75 out. When its 90 it may still be an issue. Just glad its looking good.