I took my '87 to a mechanic recently and he wired up my fan to come on as soon as I turn on the car, and turn off when the car turns off. I'm sure this isn't good for gas mileage, but does it do any damage to the car?

At what temperature should I start getting worried, and what temperature is considered ideal?

Thanks...

Richie

 

On my 87, it came with an auxilliary fan in front of the radiator. I wired it up so I can turn it on anytime I want to. I usually leave it on all the time. It's programmed to come on normally at 230 degrees. The normal fan is programmed for 220, but my aftermarket chip turns it on at 200.

The fans are electric, so your gas mileage shouldn't be affected. Damage to the car...I wouldn't think so, except it might burn the fan motor out before its time and it will take a little more time for the engine to warm up.

I wouldn't start to worry unless you see temps above the 230 range.

 

You won't hurt fuel mileage or cause any damage but there should be no reason to modify the operation of the fan if your cooling system is in good shape. If the radiator is clogged or if the radiator tubes have worn thin over the years and cannot adequately transfer heat, the fan running all the time will not keep the motor cool if the radiator cannot do its job.

Why did he recommend doing this? Did the fan turn on at all? The fan is operated by the ECM by grounding a relay. When the coolant temp sensor sends a certain value to the ECM, the ECM grounds the fan relay and the fan should start. Does your car have the Z51 or Z52 suspension package? If so it should also have a secondary fan in front of the A/C condensor and is easily visible from behind the front plate under the car.

C4's are "bottom breathers" and you can get a tremendous amount of dirt and debris sucked up into the A/C condensor and radiator thus blocking airflow through them. Keep this area clean by directing a stream of water from the back side of the radiator to flush the garbage out of the air passages.

Routine maintenance of the cooling system is important. You should do a cooling flush every few years and replace with a 50-50 mix of a good ethlyene glycol (green) coolant and distilled water. Keep an eye on the radiator hoses and replace any hose that spots that feel soft. A new thermostat of the correct temp is also a good thing to do at the time of coolant flushing.

Typical temps for a cooling system in good shape should be around 190 -210 at operating temperatures and when the temp hits 225-230, the fan should kick on and lower the temps backdown.