I cannot fix my 94's overheating problems. Last weekend I changed the thermostat, radiator cap, added Below 40 and Water wetter. Yesterday it got up to 240 going 55 on open flat ground. I checked for any debris in front of the radiator. It has an electric water pump that seems to be working. I don't know what else to do, help???

 

Obviously it was doing this before your T-stat went in, right?? If not, I'd suggest swapping that out again.. Your radiator definitely isn't blocked with a bunch of debris???? I didn't think mine was either, by looking, but when I pulled it out, it was caked.. Is your front air dam in place?? And last, your certain your water pumps working???

 

According to Corvette Magazine's Tech Nerd, 240 even under extreme summertime stop-and-go is "normal". Though he's addressing the concerns of an LT-4 owner, I've also seen a similar article of someone who was concerned that there 94 model LT-1 was running too hot at 230. It seems that is also an acceptable operating range, though 240 is pretty close to the acceptability range. If you are still uncertain about your engines cooling capabilities, have a full cooling system check-up done by a shop you trust with your car. Ask for a pressure test, check the thermostat, the coolant temp. sensor, the cap, the fan switches for proper functioning, and inspect the fan blades. Also, try a flush and fill using high quality anit-freeze of course all with distilled water. If all else fails and you still see temps that make you feel uneasy about it, then I've heard of auxiliary temp switches that can be installed to cause the fans come on earlier. Try puttin in a lower temperature thermostat, or do both and hit two birds with one stone. Each piece should be available at a shop or parts store that usually works with Vettes. Hope that helps some.

 

In heavy traffic, on a 90 degree day, maybe, but with my 160 in place I never see over 185 on the highway , so I think something's wrong. :yesnod:

 

Without a doubt, something seems wrong. The cooling system is another one of my lack luster areas. What was your original thermostat? If anything like JB666 said, check the radiator for debris which can get lodged in under the shroud. If you have a big build up of junk, clearing that out and allowing the heatsink fins to work properly will knock about 10-15 degrees off your current heat problem.

 

Running your car at 240 is BS. You`re a step away from disaster. AT 250 you start to damage the engine...why be on the edge all the time? GM really screwed up on this one setting the whole cooling system run on the edge of a disaster. BS BS BS BS I KNOW EXAUST LAWS.. :bs

 

You have a condenser in front of your radiator and most cooling robbing debree is in between the radiator and the condenser. It's hard to see. I'd do a good flush, take a look at tech tips (flushing tool). As far as your electric coolant pump, was it a Meziere heavy duty pump? If so how many miles on it? One other thing, the green stuff and distilled water is all the coolant you should need if the system is working okay. What's 40 below? There is no need for a thermostat below 180 as all of them will be open at your temps unless they are inoperative.

 

On the pasangers side there is a hole you can look in on the radiator shroud that gives you a great look between the condensor and the radiator. Take a flash light and have a look to see if there is anything between them. The other thing is are your fans working? The fact it is running so hot at 50 MPH would sugeat you posibly have a problem with the spoiler.

 

Well, How warm was the weather when you were at 55mph? My suggestion is run a high flow thermostat and bypass the fan to run all the time. Im in so cal and my vette never goes over 210 even in 100 degree weather. My fan is bypassed to operate all the time and i have a manual on off switch for the push fan in front of the condenser for those extra hot days. Just another suggestion... are your brakes dragging maybe sticking calipers? Take off the handbrake and push fhe vehicle, see if their sticking. Run synthetic motor oil and keep those temps down. I got almost 300,000 on my 1986. I just keep the temps down and fluid in all the sumps. Good luck :smash:

 

I just had a brain storm. Did you purge the thermostat? When changing a thermostat, after installation, you must warm the engine up to open the thermostat. The radiator fluid will drop quite a bit after the engine warms up. Then you must refill your radiator to make sure all the fluid that should be in there is in there... :smash:

 

Although 240 seems a little too high to me, it is important to keep in mind that the LT1/LT4 motors are unique.
Say this three times:
THE LT1/LT4 MOTORS HAVE REVERSE FLOW COOLING SYSTEMS AND ARE NOT LIKE THE OTHERS.

What does this mean? It means the thermostat regulates the temperatue of the coolant ENTERING the engine, the heads on the engine get the coolant from the radiator first, and the digital temperature sensor senses the temperature after the coolant picks up heat from the engine. So, the coolant temperature sensor sees a higher temperature than the cylinder heads see. Most of the time, the heads are about 20 degrees cooler than the coolant temperature sensor is indicating.

That been said.... bottom-breathing, road vacuuming cooling system intakes are not good for air-flow at low speed. They tend to run a little hotter in traffic with the AC on.
GM considers 220 to 230 degrees normal on the LT1/LT4.

Tom Piper

 

While I was at a vette shop another guy was complaining about his running hot-they checked it and said his guage was off by 20 degrees-but I wouldn't count on that, you might have it checked though ;)

 

Something is wrong if you're seeing 240 while cruising at a steady pace... I'm on my 3rd LT1/4 car and at cruise always see around 190F-200F...

Hopefully your radiator is still OK... I made the mistake of using 40 Below on an F-Body and it clogged the core... I bought a new radiator the same week... When I took the old radiator apart I noticed that it was really gooped up with the 40 Below... It's complete junk...

This weekend I changed out the thermostat and coolant on the Vette I purchased in January... I did this because the car was running hotter than my previous cars, about 10F warmer @ 200F in 70F weather... After changing out the thermo and coolant I dropped back down to 190F where I'm used to seeing it...

Even in the AZ summer heat when I go on vacation to visit my mother, I wouldn't see 200F until it was 110F+ outside...

 

May I recommend that you purchase or borrow an accurate digital pyrometer? It's possible that the vehicle's gauge isn't accurate. I was working my my neighbor's truck and his temperature gauge was indicating an overheating condition. I put the temp. probe in the radiator and around various spots on the engine and found that the truck's gauge was inaccurate.

 

From the factory with a 180 degree thermostat, my '92 had the ECM programned to turn on the primary cooling fan at 221 degrees and the secondary cooling fan at about 228 degrees -- even on a 75 degree day, if the AC wasn't on and I was idling in traffic the digital gauge would reach about 220 degrees before the primary fan came on and cooled it down to about 205 degrees. Since the AC high-side pressure switch also turns the fans on, on a 75 degree day with the AC on it wouldn't go above 194 degrees. The reason: the AC was turning the fans on well before the engine ever got to 221 degrees. I always pulled the shroud cleaned my radiator every two years.

After my engine work and with a 160 degree thermostat, I had Ed Wright program both fans to come on at 198 degrees rising and turn off at 185 degrees falling. Now, with a brand new stock radiator, without the AC on even on the hottest day it never goes above 200 degrees -- the fans don't come on until 198.
But, when it goes over 100 degrees ambient temperature and the AC is on, the fans can't move enough air to keep it down below 198. I've seen it go to 215 degrees with both fans running full blast. As soon as I get moving above 35 mph, it quickly cools down to 194 degrees or lower. I attribute this to both more air-flow over the radiator and more coolant flow due to increased RPMs.
Being fair, my car has AFR heads (I noticed a slight increase in idle temps with these heads -- the coolant holes in AFR heads are different than stock). And, with the heavier valve springs I also notice slightly higher oil temps. My guess is, if it was still stock, the temp wouldn't go over 200 degrees.
On a cold day (40 degrees in Florida) without AC and cruising at 50 mph or more ;) , with my 160 degree thermostat, my digital gauge reads about 172 degrees.

My 1964 C2 has a 180 degree thermostat and a conventional-flow cooling system with no AC. The gauge acts like it is locked at 180 degrees, except while warming up.

Tom Piper


[Modified by Tom Piper, 5:00 PM 5/24/2004]

 

I agree with mad madmike I had the same problem on my 86. I let the car warm up & added more anti freeze ( I had the heater on high) after doing this a few times all the air was purged from the system & the car runs normal.

 

:iagree: I think if you are getting to 240 at 50 mph you have a coolant flow problem. I just checked between my radiator and condenser by looking through the hole in the shroud on the right side. I could see leaves and stuff built up about halfway up. I still run about 197 at 75 mph down the highway. I will be cleaning this out this weekend. I think as a test I would go to a quick oil change place and have them do a flush and fill. They suck the old coolant out as they put in new. This worked very well on my daughters 97 Monte. I think this will also eliminate the possibility of air in your cooling system. If after the flush and fill, if this doesn’t help I would think it would be the water pump. Hope this helps

 

Every one seems to forget that the radiator WILL lime up inside those tubes, and the flow will be restricted, and overheating will occure. So check that ,especially if you are dealing with high mileage.

 

Running the car at the same speed when the ambient temperature was the same, did the electric water pump maintain cooler temps?

I just don't trust that they're up to the task of keeping the engine cool once the ambient temps climb during the hot months.

Jake

 

Your system may just need cleaning out. The only stuff I've found that still works is a product called Core Restore made by Plating technologies. Check out his website and give him a call. He's a nice honest guy and his stuff really works. I used it on my 86 and resolved my temp problems. http://www.finishing.com/Products/plattech.html