okay, my 87 L-98 is overheating. I have a 160 degree stat and 160 degree switch. I noticed couple of weeks ago it was running a bit warmer than usual, around 190-200. I also heard the overflow tank gurgling, I checked the fluids and all seemed fine. I figured its time to yank the radiator and clean everything out and was getting ready to do that when the car ran hot one day steadily climbing up towards 250. I added fluid and limped another mile towards home and she hit 270 quick, i shut it down and parked it. waited 2 hours for AAA to say he wouldnt tow it for fear of damaging it. I thanked him for being honest with me and added more water to the radiator, started it up at 140 degrees and by the time i got home (about a mile) it read 180 degrees. I have noticed the hot water valve to heater core is a bit leaky but otherwise not a single drop of coolant on the ground or elswhere on the engine. I checked oil and it is clean..... anyone have any ideas as to why this is happening? Oh, pulled the radiator and put in a new stat and car still runs hot. sorry so long, any ideas or help is greatly appreciated.

 

I had the same problem. I changed out the water pump.
Notice its was leeking very slighty....
With the 160 the factory EPROM will not turn on the fan until ~230 degrees.

 

:iagree:

 

You should also check the area between the radiator and the AC condenser to make sure it is clear of obstructions. That area gets REAL dirty and will prevent airflow sufficient enough to cool the car.

 

Is than fan comming on ?
Test rad cap.
If it keeps up check your thermostat out. Also be sure all air is out and you have forced enough coolant in by filling rad while revving to 2000 rpm.
:cheers:


[Modified by AGENT 86, 7:26 PM 2/10/2004]

 

I agree, check the simple stuff first. For cooling systems, generally check the rad cap first, then the t-stat(which you did), check hoses/pipes, the rad for debris, make sure the fan's coming on.

To check to make sure the water pump is functioning and the coolant's circulating, take the radiator cap off and run the car up to where the t-stat should be open. There should be a waterfall-like affect from the passages in the radiator.

 

Consider drilling 4 small holes on it (per TPIS recommendation) This will eliminate those temp spikes by allowing a constant flow of coolant at all times. My 86 used to run at 200-210 degrees in town. With 4 small holes in the thermostat it ran at 185-200 degrees with just this free mod. :D

Also, consider intalling a low temp fan switch like this. With the rest of you cooling system in good working order, 4 small holes in your thermostat, and this switch, you Vette will not see temps much over 200 degrees even in traffic. http://www.madvet.com/-/shop?store=3.&frame=944
:D

I run a 70% coolant/30% water mixture.
TPIS 170 degree thermostat with 4 holes drilled in it
Low temp fan switch. (Turns fan(s) on at 200 degrees and off at 185 degrees

On the freeway my temps stay arround 172 degrees, In town and in traffic my temps never go above 202 degrees. :D :D


[Modified by 86PACER, 3:00 AM 2/11/2004]

 

Check ignition timing.

 

REALLY?

So putting in a lower temp sensor (You ARE talking about sensor not thermostadt aren't you?) with factory eprom WON'T actually cool the car at all? QUite the opposite is what I'm reading? :confused:


[Modified by smacko, 10:50 PM 2/11/2004]

 

Had this problem. Most of it was the radiator cap not holding pressure. Tried 3 new ones before I got one that worked.

 

Agree, check the simple things first.... :iagree:

 

Wow! Listen up guys. Have you heard of the head gasket scrubbing problem with the L98? This should be a no brainer. A friend and I just changed his head gaskets on his L98 for the very same problem after he had it towed to my house. The gasket lost its integrity on the south end of number 7. We used the new 'better' grade felpro that addresses the scrubbing issue. After many thousands of miles since, he is happy. :smash:

 

Just installing a lower temp thermostat, by itself, won't allow the engine to run cooler, especially at idle. It'll just take a little longer to get up to its 'normal' hot temp.

At idle there will be virtually no airflow through the radiator without the fan being "on". At low speeds on a hot day airflow throught the radiator won't be able to keep up either.

So even though the stat will open at a lower temp and coolant will flow through the radiator, there won't be enough airflow through the radiator to remove the heat from the coolant.

The way to do it is to have the fan activate at a lower temp in addition to installing a lower temp opening stat. There are a few ways to do this; have the PROM re-burned to command the fan to activate at a lower temp; install a manual toggle switch on the dash to allow you to turn it on and off or; install one of the switches (available from Ecklers, Mid-America, etc.) in the cylinder head in place of the stock one.

Jake

 

He can rent a coolant system pressure tester from AutoZone (free) to check for a possible head gasket problem. It'll show any hose(s), gaskets that are leaking too.

Jake

 

Most radiator places I've been to here in AU will do a FREE pressure test on your system.

 

OK, have just yesterday finished putting in an over-ride switch to turn on fans.

So you DO suggest a lower than stock sensor (In the block) to turn on fan earlier?

U had me worried when I read what u were saying as to do so would keep engine temps higher!

 

You have a manual switch now.
You can cool it down anytime you want. A lower aux fan switch will take some brain work out of the equation though :jester

 

Thanks to everyone for their input. I have checked all the basics and simple stuff. Pulled rad and cleaned birds nest out from under it, replaced stat. Fans turn on at 200 and off at 185. Filled with new coolant and ran the car. Temp rose rather quickly and then stabilized at 216 at idle. I took it for a short ride(less than a mile) and it rose to 250 by the time i got home. Time to check the water pump.... car has 177.xxx miles on it and has not been touched so maybe its just time. Also I have seen the phenomenon known as head gasket scrubbing and it is not pretty what electrolosis can do to the intake. That is also an issue i am be looking at... if that is the issue....
time for goodies :hurray:

 

I had virtually the EXACT same thing happen to me last summer. Driving along a small country road not far from my place and my '89 overheated a little. So I did what everybody here has already suggested - checked the small stuff first. Thermostat, rad cap, cleaned between the rad and A/C condensor, changed hoses and belt, flushed rad, new coolant...you name it. Just when I thought that I had done so much work to the car that I was BOUND to have solved the problem (I never took the car for a test drive after each item that I fixed/replaced) I took the car out for one more spin. And BOY did it overheat on me! Coolant bubbling out of the overflow tank, temperatures so high the gauge stopped registering them, pinging and knocking noises from under the hood like nobodys business - and that was during just a short drive maybe about a mile or two from my house!

The problem? You guessed it: blown head gasket! At notorious cylinder #7 too. But it wasn't the blown head gasket that made me mad. It was the cracked head that resulted from the extreme overheating condition that occured.

Needless to say, I replaced the heads and the head gaskets myself. Took some time, but I did it. And now that I know the warning signs, I can at least take comfort in the fact that I can share my experiences with others in the hopes that they won't have to go through what I did.

Do yourself a favor - if the car is overheating, don't drive it any more than you absolutely have to. Do as much diagnostic work as you can in your own garage. Cylinders #7 & #8 are always problem areas. Pull the spark plugs on all the cylinders, put some clean rags on top of your exhaust manifolds and crank the engine over. If you see green come out of any of the spark plug holes, then you can bet it's a blown gasket. Do you see alot of white smoke with a 'funny' smell coming out of the exhaust when the car is running? That's a dead giveaway of a blown headgasket.

If you do find that it is a blown head gasket, decide whether you want to handle the job yourself or not. If not, have the car flat-bedded to a shop you trust. If you decide you are going to do it yourself, USE THIS FORUM!!! The people on here are absolutely increadible and are without question one of the best support groups anybody could ever ask for. We'll walk you through it and help wherever we can.

Good luck. :thumbs:


[Modified by TheCorvetteKid, 9:25 PM 2/11/2004]

 

Thank God for that! U had me worried there for a while, am just about to order one