I have a 2006 z06. last year I had engine work performed. heads rebuilt, large cam and intake & long tube headers(660 to the crank). This year for some reason after I turn the Air on, the heat gauge starts to go from 210 degrees 235 degrees in normal slow traffic. If I turn the air off the gauge starts to go back down to 210 degrees. I also when revving the engine sitting still to maybe 3000 RPM's I hear a winding noise in the air conditioner compressor.

Does anyone have any thoughts what may be causing the over heating or is this normal? I do notice on my garage floor, a few drops of coolant each time I take the car out of the garage. Drops maybe the size of a pencil eraser.

George Trocki
410-303-6276 cell
george@tbenefit.com

 

try cleaning the air conditioning condenser and radiator. probably full of debris (leaves,grass, papers maybe a mustang or two).

 

As mentioned.....a dirty (exterior) condenser can cause quick overheating when the A/C is turned ON.

But the whining you hear could be a compressor that's failing and causing a lot more drag on the engine than normal. The coolant leak.....that's a problem too. Possibly a water pump seal going bad.

Is your coolant low? In the radiator...not the overflow tank.....

If I were you I would get the engine up to operating temp, or a little higher even......pull the car into the driveway up on front end ramps, or a lift.....wait about 15-20 minutes then come back with a flashlight and look everywhere for that leak.

If you have a small leak somewhere, you will leak coolant after the engine is shut down, then it gets hotter for about 30 minutes before it starts to cool. The rise in pressure makes the coolant leak out of the small breach........easier to find it. People usually walk into the house after parking their car so they never see/hear a leak.....it takes more heat and pressure to build up sometimes for the coolant to get pushed out of the leak.
After the coolant pisses out there's a void in the system, that void is air that gets sucked into the coolant system while its cooling. When that void gets too big your cooling ability is shot to hell.....especially after you turn the A/C ON.

Could be a sticking tstat too, partially opening reducing flow.....then when you turn the A/C ON, its way overloaded and temps shoot up.

Gotta start ruling things out......

 

So far your temps aren't that far out of line. As mentioned above you should check for air flow restrictions that can be removed by cleaning the condenser and radiator.

Here is the description of how the fan system works:

The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.

Cooling fan speed is effected by many different conditions and can be adjusted from 10 percent to 90 percent duty cycle (PWM), 90 percent is considered high speed fan. When multiple cooling fan speed requests are received the ECM uses the highest cooling fan speed of all the requests. The ECM commands the cooling fan ON under the following conditions:

• Cooling fan duty cycle starts when engine coolant temperature reaches approximately 95°C (204°F) and reaches high speed at temperatures above 113°C (235°F).

• Cooling fan duty cycle starts when A/C pressure reaches approximately 1100 kPa (160 psi) and reaches high speed at A/C pressures above 2480 kPa (360 psi).

• At engine oil temperatures above approximately 150°C (302°F) the cooling fan duty cycle will be commanded to high speed.

• At transmission oil temperatures above approximately 132°C (270°F) the cooling fan duty cycle will be commanded to high speed.

• After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 113°C (235°F) or the A/C pressure is greater than 1720 kPa (249 psi) the cooling fan duty cycle is set to 50 percent, low speed. If the coolant temperature drops below 110°C (230°F) and the A/C pressure drops below 1660 kPa (241 psi) the fan will shut OFF. The fans will automatically shut OFF after 2 min. regardless of coolant temperature.

The fan goes to high speed at 235 which means under some conditions coolant temp could get higher and still be within reason. The ECM won't turn on the overheating warning until the coolant temp hits 256 degrees.

However, the drips you are seeing could mean trouble. Are they near the center front of the car? Get the car in the air and check the backside of the water pump to see if it is sticky or wet. When my pump started leaking I would drive the car one day and about a day later a couple of drips would fall on the floor. The harmonic balancer, belt pulley and stabilizer bar might be wet to the touch as well. If you have a leak at the pump you are losing coolant and system pressure that could cause an overheating situation.

Bill