My 85 Vette overheats on a dime. In low temps say 85-90 degrees ambient on up. turning on the air accelerates the problem of course. I have gone to all new parts new rad, new water pump, (yes it is for corvette pumps in reverse). fan motor/relay are new and operate when ignition is on or full time. I've tried different thermostats 180, 190 still, unless the car is on the highway and the ambient temp is under 90 I have an overheating problem. I have made sure there is no air pocket by drilling 1/32 hole in one of the 180 degree thermostats. I have bypassed the heater core as I do not require heater in Vegas. Thanks
Do the fans go on when the A/C is turned on?
There are pressure switches in the A/C System that turn on the fans when pressure is detected in the A/C system.
When you turn on the A/C; check to see if the fans turn on immediately. If not check the switches in the A/C system.
If you have a scanner or know someone who has one, check the operation of the coolant sensor. You have a sensor for the gauge and for the computer. If the sensor is bad the computer sensor and the gauge sensor will be different.
Check the connections on the sensors for the cooling fan relay. If the sensor is bad or corroded, it can make the fan to come on at the wrong temperatures.
This is probably not the problem but it wouldn't hurt to check to make sure.
The scanner can also check the A/C switches to see if they are working properly.
I have fans on all the time by choice. If the engine is on the fans are on. I have installed a switch to (1) turn fans on all the time (2) Turn fans on when AC is Switched on or coolant temp demands. (3) Off at all times. I leave it on constantly. Switch kit from Ecklers Corvette catalog.
No Check engine light - scan reads no trouble codes. Auto Zone reads them for free.
It vexes me that my 5.7 can't get out of it's own way due to overheating. Under 80 degrees ambient temp it's a Vette an I love driving it.
Last edited by gtovegas (5/10/2011 11:36 PM)
It sounds like the engine is still air bound.
As long as the correct water pump is installed, this could be the only thing that can do this.
When the engine is cool remove the radiator cap. Jack up the front of the car and put on stands and chock the rear wheels for safety. You can also use ramps. Run the engine until the thermostat opens and watch the coolant level. Add coolant when needed. Do this until the radiator doesn't take any more coolant.
When you jack up the car, you put the radiator higher than the engine. The trapped air will be forced to go to the radiator eliminating the air pocket.
Let us know how you make out.