My 1995 C4 is running hot during stop and go traffic. Here is what has been done so far:

1) Upgraded to a Be Cool radiator and added separate auto trans-cooler.

2) New water pump - installed by Corvettes of Dallas - no air in system – properly “burped”

3) New thermostat- installed by GM dealer

4) Block Test- not losing and fluid

5) Vehicle exhaust system check - no problems no blockage

6) Fans checked and sensors are all operating as required

7) Distributor was also replaced and oil seals fixed after water pump
Between C of D and dealership I have spent great deal of money and no resolution.

Any ideas?

If I am driving on highway it runs fine and temp averages no higher than 210.

Temp gets to about 235 according to digital reading. It does not truly over-heat, but everyone says it should not run this hot?

Go back to stock radiator??????????

Running out of money and ideas..

Thanks

 

235 is on the warm side but overall, not too bad. 210 is OK for freeway if the air temps are high. What temperature thermostat was installed? Did they replace the pressure cap? Is the coolant level at the proper height in the tank? It should be just below the rim of the opening.

Is there fluid in the overflow bottle and is it at the correct mark for hot at operating temps or at the mark for cold before the engine is started for the first time in a day?

Did they replace the radiator coolant hoses? The lower hose may be collapsing and causing a drop in flow of coolant.

The radiator should be fine to provide the amount of surface area to cool the motor. But is the motor stock? Lots of mods like a cam, compression, bigger displacement could put more of a load on the cooling system.

Did the clean out the A/C condensor coils to allow for sufficient airflow through it so that the radiator can work?

When you turn the A/C on , does the secondary fan start?

 

All that makes me wonder if the sensor is accurate. There could also be an airflow issue such as a bent or missing front spoiler, are those OK?

 

What temperature thermostat was installed?

GM dealer installed a 180 temp thermostat. Tested and they believe it is working right. Actually this is the third thermostat since I noticed it running war. COD put one on when they replaced the water pump and I had the Goodyear shop near me do the first on.

The coolant level is fine and at all the required levels....

I just ran out and check the level in the over-flow tank and it is right at the "cold" level as required because I haven't started it this morning. Popped the cap on it and the other level itself is perfect. No loss in any fluid. I have been driving for two weeks since last repair (oil seals on engine).

I also noticed they put on a new radiator cap.

As for the hoses the GM dealer even put on some clear hoses to test the flow through to make sure there wasn't any blockage itself and it preformed as expected and they found proper flow in both upper and lower hoses.

Motor is stock and has no changes at all. No chips and no aftermarket anything.

AC coils are clean and the fan does kick on when I turn the AC itself on.

Running temp is fine in the morning when 50 degrees or 60 degrees I average 194 average.

Anytime over 75 degree outside temp and sitting in traffic the temp climbs. Not uncommon for it to jump 10 degrees while at a light.

Just lost on other ideas.

 

You have thrown bunches of money to cure symptoms. Not one would I argue with. However, has anyone checked the temp senders and/or the gages? With what you have done I would be inclined to think the basic measurement is suspect.

 

All that makes me wonder if the sensor is accurate. There could also be an airflow issue such as a bent or missing front spoiler, are those OK?

No problems with spoiler. Replaced it front lower spoiler....

http://cgi.ebay.com/ebaymotors/1991-...QQcmdZViewItem[/COLOR]

 

You have thrown bunches of money to cure symptoms. Not one would I argue with. However, has anyone checked the temp senders and/or the gages? With what you have done I would be inclined to think the basic measurement is suspect.


Replaced sensor when water pump was done. COD still could figure it out so the moved it to the GM dealer for me. Thats when the replaced the thermostat again.........

 

my car seems to do the same thing, nice and cool on the highway and around 230 in stop and go traffic. It really bugs me. The front spoilers should not have anything to do with it since when you are stopped in trafic there is no air to move. Some people said to me that these cars just run warm in traffic. I dont know what else to do with mine.

 

While visually seeing flow is fine while the car is sitting in the shop, once you start driving and the coolant is circulation, there is a possibility of the lower hose collapsing simply due to old age. Most lower hoses have a metal coil inside to help keep the hose open. If this coil is broken or has botten weak and the hose is old, it is possible for the hose to collapse. If they are the original hoses, keep in mind they are 12 years old.

My 92 would also show a rapid climb in coolant temp while sitting at a light. Depending on the length of the light, the coolant temp when you stop and how fast you are travelling in traffic, that can cause a quick rise and the temps may stay up longer.

If you simply start the car and let it sit until it gets to operating temp, you should see a temp swing as part of normal operation. The coolant temp sensor is monitored by the ECM; once a certain resistance value is seen, the ECM sends a ground signal to the fan relays which then starts and stops the cooling fans based on temp.

The secondary fan should come on at around 234 degrees and shut off once the coolant temps drop about 38 degrees. The primary fan starts around 226 degrees and shuts off after about a 41 degree drop in temp. (these temp values are from my 92 FSM, the temps for the 96 could be slightly different)

The fans are controlled by the ECM based on inputs fron a number if things: A/C system pressures (when running), Coolant Temp Sensor, Engine Oil Temp Sensor, Vehicle Speed Sensor and engine RPM. It's entirely possible for any one of these sensors to be slightly off and allow the engine to run warmer that what you would expect.

Using a 180 degree stat really only indicates at what temp the thermostat opens. Once it's fully open, it really does not have much to do with cooling temp control.

All in all, the temps you see are not too bad especially if the ambient air temp is above 75. Late model cars are designed to run hot (or at least what we think of as "hot") in order to reduce exhaust emissions. It also keeps the engine from forming deposits. You didn't mention oil temps, but typical LTx oil temps are around 10-15 degrees higher than coolant temps. With synthetic oil, this is not a problem.

 

That great.... I have heard older Vettes run hot from some Vette guy at Goodyear shop.

I am just making sure it running as designed. C of Dallas thinks it should not exceed 190 and said anything else they would do is inside the engine itself.

I just wanted to get some closure on this... Trust me when I say I have spent so serious money and just want to enjoy the car and drive it.....

 

Nothing is wrong with the car, That is designed operating temp.

 

You just answered your own question on the airflow. That is exactly why they run so much hotter while sitting in traffic. In order to run cooler, requires airflow through the radiator.

To get airflow requires one of two things:
1. Car has to be moving greater than approx. 40mph
2. The electric cooling fans need to be running

It's a well known fact that the factory settings for the cooling fans won't command them to come on until temps. are in the upper 220 range. Note: You can also turn on the A/C and they should come on.
This is one car that will actually run cooler with the A/C on (assuming your cooling and A/C system is in good condition).

So, if you want your car to idle in traffic cooler than 190-200 range your going to have to modify your cooling system from what the factory had set.

220 - 230 while sitting in traffic is not too hot for a modern well maintained cooling system though. It's too hot for some people to live with, but that's the way they left the factory.

 

Install a toggle switch to turn on one fan any time you want. OR
Have a chip burned to turn the fans on at 210 or somrthing like that,
PCMFORLESS will do this mailorder. Or Both My 2cents
You know how hot vegas gets, 110 is common with 115 several times each year, the road is about 200, cooling system dosent have a chance without the fan running.

 

http://www.mamotorworks.com/corvette?frame=1.943

Is this what you are speaking of??????

 

Here's two problems. Goodyear Service Centers are not a place I would go for service. While they do repairs, they are a tire shop. I just dont' see them having technicians specifically trained as Corvette technicians.

I would like to know where Corvettes of Dallas came up with a statement like that. I would raise the flag here. Same with going inside the motor to cool it down. That doesn't even make sense. It sounds like they are trying to sell you work or parts that are not needed nor necessary.

You're OK with what is going on. I just don't see any reason to go further. I'm not a fan of running the fans constantly or changing the temp at which they come on. While it may keep the temps down by more fan runtime, it can also cover problems that might occur later.

 

Went to Goodyear because they have a Vette specialist (good friend of mine -has one of his own C-4's) and they were just replacing the thermostat.

He stated that it was normal for it to run this warm.

As for COD I am not returning for any additional work. Spent money and like I said they kept saying it should not get higher than 190 degrees, thus they transferred it to a GM dealership for their expertise.

Any way, just happy to hear this is temperature is normal. I do not think I need the fan relay over-ride and let the factory equipment work as designed.

 

Is COD some sort of vette specility shop?
that said higher than 190 is not normal. ?
You should RUN as fast as possible and just accept your loses.

actually buy a FSM, and read the cooling section.

 

COD = Corvettes of Dallas - thought they would be specialists......

 

If it really bothers you get a hypertech programmer about $200.00 bucks ,install a 160 stat and reprogram the fans yourself.
With that device you can reprogram the tire size cooling ,engine,speed for gears and so on.
Put on your track shoes and run from that Dlr as fast as you can
Mine runs about 185 to 175 above 55 and in traffic about 210 to 220 even after I reset everything.

 

I did grab a 160 hypertech thermostat, but it sounds like it really doesn't help that much..... So, it is still in the box..

Figured if I used it I would have to reprogram it...

It is cooler here in Texas now, so may do next summer.......