At 01:47 AM 1/14/2008, John K wrote:
Has anyone recently replaced their factory fan unit (behind the radiator) with an upgrade? I have a 91 GT, with the stock twin fan setup, and remember a while back a kit that replaced just the fans and motor for higher output. I don't have a reference to that any longer though. I would assume it is similar to 928 Specialist Twin fan setup but for about $150 only. I also have a second "pusher" fan for the front I have not yet installed. Anything to help keep the engine a bit cooler. As you can probably guess I have a slight heating problem. It only gets slightly warm, just touching the red area in the water temp gauge. Mostly on hot days and with the A/C engaged. Anyone have any leads? On a cool night the temp. is MUCH MUCH lower. Its primarily this "swing" in the overall temp that has me looking to lower it.
Of course one of those fancy aluminum radiators will be my last choice.
The first thing to do is to check the temp gauge - it is not a precision instrument. An over-heating engine feels hot and smells hot...
If both of the currently-installed fans are running at full speed when the temp is high, more fans probably won't help.
Overheating at idle and slow speeds is usually airflow. Overheating at normal and highway speeds is usually coolant flow.
If your problem is low-speed overheating, and both fans operate properly, check for air recirculation (missing belly pan, seals missing around the radiator, etc.).
It is possible that the thermostat has failed, or that the seal behind the thermostat is faulty. This could result in sufficient cooling when the outside temp is low, but insufficient cooling when the outside temp is high.
Another possibility is a partially-plugged radiator. When the engine is hot, feel the radiator. There should be a slight difference in surface temps - if some areas are cold and some are hot, the radiator might well be plugged. A good radiator shop will be equipped to remove the end tanks and clean out the core.