overheating on '94
Thread Starter
1st Gear
Joined: Apr 2004
Posts: 1
Likes: 0
From: Clearwater fl
overheating on '94
I have a problem with overheating when I do not have the air-conditioner on. I know having the air on runs my radiator fan but, when it is off the temp just keeps going up. I'm not sure if the sensor on the thermostat housing is bad or its something else because my gage seems to be giving me a good reading. Does anyone have a suggestion how I can diagnose the problem and what the normal operating temp should be?
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: overheating on '94 (Johnk)
94's have a 2 stage fan... the first kicks in at like 225 and the 2nd at like 235... and they are 2 speeds...
check the fan relay... I would think you might have an electrical problem.
do you have the helms manual? if not, you must get one!!! without it, you won't ever solve this problem.
check the fan relay... I would think you might have an electrical problem.
do you have the helms manual? if not, you must get one!!! without it, you won't ever solve this problem.
Team Owner
Joined: Sep 2001
Posts: 62,137
Likes: 1,727
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: overheating on '94 (Johnk)
They all run hot. You should run a search in the archives and youll find hundreds of threads on the problem.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: overheating on '94 (Johnk)
What temps do you see (digital gauge, don't trust the analog one!)?? In warm weather in city traffic, it's not uncommon to see temps around 200-230 before the secondary fan starts. As you said, running the A/C forces the secondary fan on to help with cooling.
Open the hood and let the engine run as you observe the fans. Does either fan come on? Once temps reach over 230 or so, does the secondary fan start? Will the secondary fan start when you run the A/C?? If not, you may have to replace the fan relays.
You may also have a bad thermostat if the temps are consistently too high. In any event, I would recommend having the coolant system completely flushed as described in the service manual (get the Helm factory service manual for your year). Use a 50/50 mix of a good quality green coolant and distilled water (that's the recommendation in the service manual).
You should probably replace the thermostat and you can use a 180 degree stat if you want and also have the pressure cap replaced.
Also check the front of the radiator for any debris that can be clogging the radiator core. If you look up under the car behind the front license plate, you will see the A/C condensor. Check it for debris. You should be able to see the front of the radiator through the side openings of the fiberglass shroud on the right side of the radiator. Use a stream of water to flush any junk out of the core. Messy job but this one alone may solve a lot of overheating problems.
Open the hood and let the engine run as you observe the fans. Does either fan come on? Once temps reach over 230 or so, does the secondary fan start? Will the secondary fan start when you run the A/C?? If not, you may have to replace the fan relays.
You may also have a bad thermostat if the temps are consistently too high. In any event, I would recommend having the coolant system completely flushed as described in the service manual (get the Helm factory service manual for your year). Use a 50/50 mix of a good quality green coolant and distilled water (that's the recommendation in the service manual).
You should probably replace the thermostat and you can use a 180 degree stat if you want and also have the pressure cap replaced.
Also check the front of the radiator for any debris that can be clogging the radiator core. If you look up under the car behind the front license plate, you will see the A/C condensor. Check it for debris. You should be able to see the front of the radiator through the side openings of the fiberglass shroud on the right side of the radiator. Use a stream of water to flush any junk out of the core. Messy job but this one alone may solve a lot of overheating problems.
Drifting
Joined: Jun 2002
Posts: 1,305
Likes: 11
From: Savannah Ga.
Re: overheating on '94 (vader86)
QUOTE---------------------------------------------------
they all run HOT
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:iagree: just keep an Eye on the temp gauge more often esplly in stop and go traffic and when idling for a long period of time......open window put therm on 90 turn on let heat escape thru interior air vents when you get caught in heavy traffic.... :chill: just learn how to mange in different situation also make sure trash is not covering radiator...PEACE!!!
Burning Brakes
Joined: Dec 2003
Posts: 770
Likes: 0
From: Madison Mississippi
Re: overheating on '94 (Johnk)
John, I had the same problem. Temps kept creeping-up. I finally solved the problem by pulling the radiator out and cleaning between the fins. I found that Corvettes are vacuum cleaners. I discovered mine had plastic bags, leaves, rocks, and tons of grass jammed in it. You will not believe how awesome the radiator is until, you see how well yours is actually cooling slammed full of dirt. It takes about thirty minutes to pull it out. No biggie. Just remember to drain it at the bottom and don't get any water on your OPTI. Good luck :steering:
