96 C4 Lt1 Overheating
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From: Compound in the Grove, Ga.
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Not sure if this works on a 96, but on the 95 you can ground the solid blue wire and the solid green wire at the fan relays on the left side of the fan shroud to turn on the fans.
Le Mans Master
Joined: Jan 2006
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From: Orlando FL
This is a very common cause of overheating in C4's. The C4 is sometimes referred to as "bottom breathers" as air comes up from under the front bumper cover and into the opening where the A/C condenser and radiator are located. If the openings around the fins and tubes of the two components get blocked by dirt, debris, Honda's, etc, air flow can be significantly reduced and that causes overheating.
You can vacuum out some of the gunk, or use a garden hose to spray the back side of the radiator to force stuff out. This part is pretty easy to do and it's also free!!
Another thing to check is the air dam under the car. That air dam works to direct air up into the cavity so it's pretty much a necessity to have in place.
The usual coolant temps for C4's are designed to be higher as those higher temps help with reducing emissions. Temps in the 195 to 220 range are not a problem.
You can vacuum out some of the gunk, or use a garden hose to spray the back side of the radiator to force stuff out. This part is pretty easy to do and it's also free!!
Another thing to check is the air dam under the car. That air dam works to direct air up into the cavity so it's pretty much a necessity to have in place.
The usual coolant temps for C4's are designed to be higher as those higher temps help with reducing emissions. Temps in the 195 to 220 range are not a problem.
What does "but then it shoots off the chart" mean in real numbers?
A basic check:
Remove the surge tank cap when the engine is cold. Start the engine and look in the tank and then rev the engine up a bit (~2000). You should see the coolant level drop and a good flow from the inlets to the tank. This would insure the pump is working pretty normal. Also, don’t know if this could be a factor, but if the flow is to fast from your high volume pump, it may not allow the coolant to cool sufficiently in the radiator.
You can't see the real dirt in the fins of the radiator and condenser. I fabricated a shallow 90 degree angle air hose out of a mop stick (or broom handle) using rubber hose and fittings. Real crude, used duck tape and hose clamps but worked great. I removed the plastic cover over the radiator so I could get in-between everything. I blasted the air from both sides of the radiator and the condenser. Did it many times till stuff stopped coming out and spend about 1 hour doing this. What a difference it made as it brought all my temps down and they don’t climb so fast any more.
In Orlando, my ambient air is 90-100 in the summer which is months long. Things really have to work properly as cooling is always an challenge for the vette.
This is true, DARK GREEN and DARK BLUE must be grounded at the same time for fans to go into high speed.
Last edited by pcolt94; Aug 15, 2015 at 01:23 PM.
Pro
Joined: Feb 2002
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From: Augusta Ga
I had an overheating issue on my Lt-4, replaced the thermostat and it's gone now. The thermostat didn't look bad at all but it was the culprit. The two gauges were off from each other and I could only get it to cool when down shifting and getting the RPMs over 2k. The thermostat I had was the kind without a bleeder hole and fails closed. The one I replaced it with fails open and has a bleeder hole. Both temp gauges agree now and the vehicle stays at around 210.
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From: Port St. Lucie West Florida
Team Owner
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From: Park City Utah
I think the OP is MIA now though....
Last edited by Tom400CFI; Oct 18, 2015 at 10:23 PM.
