Engine Over Heats

[accucast]

I have a 1990 corvette coupe. It overheats after driving in town about half-hour. If I come to a stop light, it will start climbing. I take off and go about 40 or so it will cool down. I have taken it home, turned it off and came out the next day and started it up and let it idle in the drive way and it never did hea up. I can't figure it out. Any ideas? The coolent is full when this happens.
Thanks for any help
Steve Robinson - Indianapolis, IN
cpl@insightbb.com

 

[redc4corvette]

What is the temp gauge reading?Have you checked the front to see if a bag or leaves are blocking raidator?

 

[Ken]

The fourth-generation Corvette is a "bottom-breather", that is, it needs to be moving in a forward direction to keep air moving through the radiator in order to maintain coolant temperatures. The coolant fans can't quite maintain enough flow through the radiator when idling in traffic and such. That's why you see temperatures drop once you get underway again, although in the interest of cleaner air, the engines are "designed" to operate at higher temperatures than what we're used to seeing in the past. It's not uncommon for the C4 to see 120°F or more in heavy summer traffic.

Another and often overlooked important part in directing the airflow through the radiator is the lower air dam at the front of the vehicle. If it is missing or damaged it will cause the vehicle to see elevated temperatures.

 

[wannavette]

thought the same thing about mine till I found out 220-225 in traffic was not uncommon.I think I read in 1 of my books that I have not to be worried until it starts hitting 255-260.I still cringe @ the thought of my car running that hot

 

[WhalePirot]

Cool! A '90 with only 34k!

It's not uncommon for the C4 to see 120°F or more in heavy summer traffic.

Umm, typo. He means 220.

Many threads refer to checking for debris between the A/C condenser and the radiator; an easy thing to do. Ken is spot on with the 'spoiler' condition, but I cannot agree with the lack of cooling while in traffic. While the temperatures allowed by the design are (alarmingly) high, for the stated reasons, they are normal and if the cooling system is properly operating, the car should not overheat while idling. They are tested in desert-hot conditions, with the A/C on, and while losing some efficiency with age, will cool the car as designed, with proper maintenance.

Above about 40 mph, the fans move equivalent air to the airflow and are not needed above this speed. A big clue that a cooling problem lies with the fan(s), as long as airflow is not obstructed, is adequate cooling while driving above 40, or so. Similarly, turning on the heater can indicate if the car needs more radiator capacity.

Switching on the A/C will activate the fan(s), telling you that the relay and fan are fine. Idling at your home, with normal indications would seem to say the same. I suspect you see the fan cycling on and off. If you want a lower fan 'trigger' temperature, the ECMcan be programmed, as indicated in many, other threads.

Surely, check or leaves and such first, whatever you do.

 

[Jeb]

thought the same thing about mine till I found out 220-225 in traffic was not uncommon.I think I read in 1 of my books that I have not to be worried until it starts hitting 255-260.I still cringe @ the thought of my car running that hot

Well, that answers my question from another thread. Thanks a bunch!

 

[Ken]

Hey Mike, my Vette never gets above 120°, honest! :L

 

[Vettelt193]

I have a 1990 corvette coupe. It overheats after driving in town about half-hour. If I come to a stop light, it will start climbing. I take off and go about 40 or so it will cool down. I have taken it home, turned it off and came out the next day and started it up and let it idle in the drive way and it never did hea up. I can't figure it out. Any ideas? The coolent is full when this happens.
Thanks for any help
Steve Robinson - Indianapolis, IN
cpl@insightbb.com

the other thing is idling in the driveway is vastly easier for a car than stop and go traffic... the engine doesn't really do much of anything idling, but stop and go it has to move the car still, and driving even at slow speeds will create more engine heat than straight idle.