8686corvette

I have a 86 Corvette and it is always hot.

I live in Orlando and for the last 2 years, I have fought to get my engine temp down. I have replaced a cracked radiator 7 months ago. At the same time replaced my thermostat.

I have been advised recenlty to clean my radiator. I will pull it tomorrow and clean the fins as well as between the radiator and the condensor. I tested the engine and for some reason the fan is not comming on at 228 like it should. It is comming on at 238. Does this mean the switch is bad? If so, should I go ahead and upgrade to the 160. Where is the fan switch located?

I went ahead and bought a new thermostat. Instead of the stock 195 therm, I got the 180 performance thermo. I also bought some wet water to add.

Any thoughts would be greatly appreciated. Next I will have to find out why the oil gets so hot, but one thing at a time.

Special thanks goes out to Vader86 :cheers:

You have been very helpful :auto:

best_vette_yet

The correct answers to your problem will only come if you tell us more.

1) does it run hot only in stop and go traffic?

2) does it run hot driving down the highway at 45mph or higher?

3) what condition is your water pump in?

4) if it does run hot in stop and go traffic, what happens when you rev the engine up to say 12 rpm?

5) does at least one of your cooling fans come on when you turn the A/C on?

I could think of more but dinner is calling me.

Let us know.

8686corvette

Okay, lets see here. That is alot of questions.

1)Yes, it only run hot when stopped in traffic. Once I start moving, the temp drops.

2)no, does not run hot while driving.

3)Don't know about the water pump. It is probably the original one. There is no leaking from the weep hole.

4)When I am sitting in traffic, even if I rev the engine, the temp continues to rise. Even tried putting car in neutral and reving up to 2000 rpm, no change.

5)I only have one cooling fan. I had the relay and motor changed 6 months ago because they fan motor was going bad and pulling so many amps , that it kept burning out the relay.

I think that about covers it.

Thanks :cheers:

Fast Glass

If all else fails, you might want to get the aux fan and install it. I got a kit from Mid America p/n18247, and installed it on my '87. It's a fairly easy install if the plug on your drivers side cylinder head between #1 & 3 cyls. comes out. Mine was stuck in there pretty good (dissimilar metal corrosion), and stripped the plug trying to get it out. I had to drill and easy out it. Once it was out though the install only took about 20 minutes, and dropped the temps down.

best_vette_yet

Does the fan come on when you turn the a/c on?

CentralCoaster

I would check the coolant temp sensors. These pickup corrosion which insulated them, so that heat is conducted to them from the engine rather than from the coolant. The computer uses one of these sensors to control the aux fan and other things I'm sure, and a seperate one for the reading you see on the dash. The reason I say this, is because you mentioned your fan appeared to be going on 10F too late. The fan is using a different sensor than what you're reading, so for some reason, they're 10 degrees off, which is huge.

What is the overall condition of your coolant system? If it sits in there for awhile it will corrode and basically turn to mud. Also, are you losing coolant, or does it always stay up to level? Use dionized water 50/50 with antifreeze to keep the rust from forming. If your overflow tank is working properly, it will keep air out of your coolant and keep corrosion down.

8686corvette

The fan doesn't seem to come on when the A/C is turned on. The A/C stopped working just prior to the winter, don't know why?

8686corvette

Where is the coolant temp switch?

8686corvette

The coolant system seems fine. I run 50/50 mix in the radiator and never have to put any fluid in the radiator.

The fan used to come on when I turned the a/c on, but like I posted before, once the a/c stopped working, it's not the same.

davevette

I'm pretty sure that if you get a manual fan switch, from any of the suppliers...Eckler's, Mid-America... under $20.00 if I remember right. That way anytime you are in traffic, you just flip it on. I put it on my'94 because I had the same problem. (it's hot in Florida) Work's great and is an easy install. The other suggestions here are also very good. Had paper covering half my radiator; didn't know to check until advised on this forum. Good Luck

best_vette_yet

You have found your problem. It doesn't matter if the a/c compressor comes on or not. What matters is you requested it to come on and your computer will turn on your aux fan any time you request a/c. I am sure you have your a/c on in the summer when your car is over heating. If you don't have adequate air flow you condensor (which is in front of the radiator) can't get rid of it's heat and now your radiator can't get rid of the engines heat or the condensors heat. That aux fan has to come on when you request a/c. Fix that and you have fixed your problem. It's too much hassle to post wiring diagrams here so I'll e-mail them to you in a .pdf file format.

8686corvette

You know it. The first thing on my list this summer is to get the a/c fixed. I am not sure why it died. Maybe the compressor. They don't last long here . :steering:

best_vette_yet

You have mail. Reply and let me know if the attached file went through. If you need anything else just ask.

Good luck :thumbs:

jfb

The a/c will turn on the fan only if the gas pressure is high enough. Your a/c probably doesn't work because it has low freon and low freon won't make enough pressure to turn on your fan. Recharging won't fix the leak, be sure to find it first. The ECM turns on the fan at 228 and a switch on the left head between #1 and #3 spark plug turns on the aux fan at 238 F. My 87 NEVER turns on the aux fan because the engine never gets to 238. You can install a small toggle switch to the fan relay, from the green/white wire to ground and when the switch grounds the gn/wh wire, the relay will close and turn your fan on. You do not need to spend $20 for a toggle switch and 12 ft of wire. Your radiator MUST be cleaned periodically because all manor of small and large debris clogs it up. I'm lazy and I clean mine by blasting water from my garden hose backwards through the radiator and then around the gap around the filler cap to flush the debris out. I find it helps a lot. I always use the 195 stat and I had my best effect on high engine temps while stopped at lights in 90+ temps (summer here) when I replaced my just starting to leak water pump with a Stewart pump (41% more flow and $104 to my door). Instead of 210-215 with my fan on via the switch, I get 200 and it quickly drops to 195 when I get underway. My opinion is that you do not need to install the auxilliary fan, but you do need to clean your radiator. I also cleaned out the small stones from the front of the a/c condenser and straightened out bent fins (that helped too). I highly recommend installing a Stewart pump. Also, be aware that 220 F will not harm your engine and I believe that we (including me) are so troubled by seeing these temps because older cars we have owned would have been boiling and leaving us stranded with these temps. I hope this helps.
PS a 160 thermostat won't do squat, it will be wide open and the temperature will settle where the radiator can get rid of heat as fast as the engine makes it which will be just where you observe it now with the factory 195 stat when the coolant is above 195!!!!!!!!!!!!!!!!!!


[Modified by jfb, 10:32 PM 3/7/2003]


[Modified by jfb, 10:35 PM 3/7/2003]

8686corvette

Got the file. What is the diagnostic terminal. Is that the ped under the dash where my mechanic hooks up the computer. If so, how do you ground it

jfb

The diagnostic terminal is the second terminal from the right on the top row of terminals on the connector by your right knee. You can use a key, paper clip, or any conductor to short between the diagnostic terminal to the terminal to its right.
Turn on your ignition sw to the run position (engine not running) and jump the diagnostic terminal and any stored error codes will be signaled by the service engine light. The SES light will flash 1,2 and do this three times followed by the error code and repeat. Just count the flashes for the error code.


[Modified by jfb, 10:47 PM 3/7/2003]

severe-1

As far as your air cond...

Have the press checked. If it is low, have them check for leaks. If there is pressure, and the A/C doesn't kick, you can "jump" wires at the pressure switch plugs. There are three pressure switches on the drivers side, one up top by the fan motor, and two between the fender and exhaust. With the car running and A/C switch on, pull off each plug and "jump" the wires together. When you "jump" one that turns the A/C on, you found the bad switch. Their easy to replace, and fairly cheap.

I replaced one last year, and another one today. I checked the date on the one I pulled out, and it was an 85(my car is an 86).

The other thing you can do (before you bring it to someone to check the pressure) is check for continuity on each of the switches. The switches have to all be "closed". If all three are "open", then you probably have a leak. If two are "closed" and one "open", then that one is probably the bad one. You can than "jump" the plug just to double check...

Hopes this helps after you cool the motor down. Than work on keeping yourself cool (got to have your priorities straight).

Man it's late...

jtfrog

get the fan switch that turns the fan on at 200 deg. I replaced the thermo and radiator but the best thing was the fan switch

loveetts

My 86 corvette turns off when hot. after an hour and a half of sitting turns on and works just fine. please help.

AGENT 86

Is there spark at plugs, when it's dead ?
If not, you may need a new ignition control module in distributor.

You should start a new thread, this one is 8 years old.