Please help, my new 1987 Vette is overheating!

[Wollven]

First a little background off of my chest - I just bought my dream car two weeks ago - a 1987 Coupe; a little rough, but I'm not made of money. I'm going to turn 38 and the wife agreed to my toy. Anyway, on to the question.

After two weeks of Corvette bliss, I awoke to find the contents of the radiator overflow res on my driveway. The car now gets to overheating very fast, and at 200 degrees, I squeezed the hoses to the waterpump from the radiator and felt no presure. The question is, do I just change out the waterpump and thermostat or could this be something worse than those things? I think I can handle changing out the wp on my own, but I'm a little apprehensive.

 

[Vettefan87]

What exact temps are you seeing anywhere from 230ish or so for coolant and oil is not overheating. I would check to make sure you do not have any air pockets in the system, do the temps come down when you are on the highway? Check the radiator make sure you have no leaves, bags etc etc blocking airflow.

 

[nyernga]

Not knowing when the last radiator flush was done is why it's best to change ALL fluids when you buy a used vette. It could be as simple as a stuck t'stat of as bad as a broken water pump. Remove the radiator cap and run the car until warm. You should see the antifreeze moving if the pump is good.
If the pump is working have a good radiator flush done and change the t'stat. Hopefully the radiator itself isn't too far gone. Also check up under the front for debris in front of the radiator as well. Trash is notorious for being sucked up under there and blocking the fins on the radiator.

Len

congrats on your new toy......treat her well and she'll return the favor....

 

[Wollven]

What exact temps are you seeing anywhere from 230ish or so for coolant and oil is not overheating. I would check to make sure you do not have any air pockets in the system, do the temps come down when you are on the highway? Check the radiator make sure you have no leaves, bags etc etc blocking airflow.

I haven't let the temp go to high...she normally runs around 200 degrees +/- 5 (coollant), but the temp got to around 225 and was still climbing when I shut her down. I turned the heater on and got the temp down temporarily. I haven't had the courage to go out on the highway, although not too much stop and go here in Tallahassee.

I'll check for blockages.

Thanks for the quick reply!

 

[Wollven]

Not knowing when the last radiator flush was done is why it's best to change ALL fluids when you buy a used vette. It could be as simple as a stuck t'stat of as bad as a broken water pump. Remove the radiator cap and run the car until warm. You should see the antifreeze moving if the pump is good.
If the pump is working have a good radiator flush done and change the t'stat. Hopefully the radiator itself isn't too far gone. Also check up under the front for debris in front of the radiator as well. Trash is notorious for being sucked up under there and blocking the fins on the radiator.

Len

congrats on your new toy......treat her well and she'll return the favor....

Thanks Len,

The anti-freeze and brake fluids were the only ones that I didnt' replace, and only 'cause the guy I bought it from had just done it (got the reciepts). I'll check the front and I'm going to look at the flow tonight!

As a side, love those chromed wheels, that's definately on my "things to do" list.

Thanks again!

Correy

 

[JonM]

Those temps ain't that bad...however sounds like you have a case of crap between the radiator and the Ac Condenser...these are bottom feeders..(suck up air from under the car)...and this accumulates all types of stuff between the two...see of you can see a flashlight through the two...especally the bottom half. You should pull the radiator and clean both with an air hose...be careful the side tanks are plastic on the radiator and get brittle with time...change the petcock while its out, its only a buck or two.

 

[MBDiagMan]

You need to tell us exactly what you are calling overheating. You said you tested the hoses at 200, but what is the max temp it reaches?

Don't replace the water pump that would be a long shot. Disconnect the wire from the aux fan sensor switch on the left side of the block and ground it. Make sure that when you ground it the aux fan turns on. That said, the stock switch doesn't turn on the fan until something like 228 degrees. If it reaches 228 without boiling then the system is probably tight.

I would recommend that you take it to a local radiator shop and let them test it with their pressure tester and go from there. It won't cost much and they will usually tell you what is wrong with it.

If you're going to have such a toy, you need to be ready for lots of issues. The way I look at my Vette, I have to drive it because I know something is going to break, so by driving it, I know what parts to buy next.

 

[Wollven]

Thanks Doc,

She was "normally" running at 200 (4 hour drive home from Orlando, on I-75/10). After the antifreeze on the drive, she got to 225 within 5 minutes of idling in the garage (ambient temp in the low 70's). I shut her down before it got any hotter but, from reading the other posts, that is not too high. I'll try to see how hot she gets tonight and I'll post back.

The fan kicks in at 185.

I thought I was ready for lots of issues, I guess I was expecting at least a month or two under my belt first...

Thanks Again!

 

[Vettelt193]

If you need help, just let me know... we can get together and take a look at it. I'm on the east side of town.

 

[nyernga]

As a side, love those chromed wheels, that's definately on my "things to do" list.

Thanks again!

Correy

Thanks Correy, they definately make the car look better. I did the wheel exchange program but when you're ready, I'll tell you which company to avoid.....

Len

 

[Wollven]

If you need help, just let me know... we can get together and take a look at it. I'm on the east side of town.

Thanks, I'm in SouthWood, I'll supply the beverages...

 

[Vettefan87]

So your main fan turns on at 185? You cant miss the sound of it, it sounds like an airplane. If that is the case and your Tstat is 195, then you are probably fine because I have a 160 stat, and my main fan turns on at 175, and my temps run about that also. Good luck it is not hard to go underneath the car and look between the condensors.

To expand on what MBDiagMan you can go to AutoZone and put down a deposit and get a radiator pressure tester and find how much pressure it is holding at, it is easy to use just screw it on top where the cap would go.

 

[MBDiagMan]

Once you ensure that you have no high pressure leaks, there's probably not a lot to worry about, but that said, it bothers me that it's running 200 while running down the road at speed. It should run pretty darn close to thermostat temp.

As one of the previous posters said, it's not too hard to pull the shroud off the top of the radiator so that you can ensure that there is no trash or obstructions between the condensor and radiator. Vacuum it out as much as you can while the shrould is off.

As a general rule I think that a switch that turns on the aux fan at 185 is turning on at a temp that is a little too low. The reason I say this is that when on the open road the fan will be on all the time which will wear it out fast. On the other end of the spectrum, the factory switches don't turn on the aux fan until 228 and the coolant fan until 240. I think those are too high.

The aux fan switch connects directly to the aux fan relay so it is easy to know when it should come on. The aux fan is the one in FRONT of the radiator.

The coolant fan OTOH is actuated by the ECM, so even though the coolant fan switch is an input, the ECM may not use this as the only determining factor for when the fan is actuated. The ECM is also monitoring engine temp.

The long and short is to first make sure that there are no leaks anywhere and that your pressure cap is holding okay. You can check it with the same tester that is used to check the radiator. As vettefan87 suggested, get a loaner at autozone and check them both.

Once you know there are no leaks and the radiator is clear to receive air, next check the fans for proper operation and then settle in and enjoy the car.

Good luck,

Good luck,

 

[Vettelt193]

Thanks, I'm in SouthWood, I'll supply the beverages...

Sounds great... you have a PM waiting

 

[MBDiagMan]

vettelt193,

Since you are on the verge of attacking your cooling system I would like to make a suggestion:

There are many folks who will want to sell you an expensive flush service or flush chemicals. In an older car using such chemicals will OFTEN cause leaks in radiators and heater cores.

The safe bet, if you decide to flush the system at all, is to flush THOROUGHLY with WATER ONLY. FLUSH, Flush, flush until you are getting only clear water coming out. THEN replace with a 50/50 mixture of Prestone and DISTILLED WATER ONLY. The calcium in tap water is a source of corrosion.

Best of luck,

 

[lagasvd]

Here's a link to help clean out the radiator between the radiator and the AC condenser.

http://www.batee.com/corvette/dcrg/readerstips/larsstuff/this_tech_paper_will_discuss_sim3.htm

 

[Wollven]

Thanks for everyone's help on this. I didn't realize the sheer power of this forum. I really appreciate the level of knowledge and insight that everyone is able to provide, even with the vague description I was barely capable of providing.

I went back last night and ran the car with the radiator cap off and got some flow, and the car ran right at temp (195-205) for a good 1/2 hour ride. From everything I have read here, I'm thinking that this is a sticky t'stat. I'm going to flush the radiator as Doc has suggested and replace the t'stat (I've heard that a 180 is good for the North Florida climate). Bob, I'm going to take you up on your offer (you have mail).

I'll post when I'm done, Thanks again for all of the help!

Correy

 

[MBDiagMan]

A 180 or 190 tstat will work fine. Going below a 180 will give a little more power but will cost you in engine life. I would not recommend going below a 180.

Flush with water only. In an older car flushing with chemicals could cause you to lose a radiator or heater core.

Good luck,