Hi Guys

I've read about the type of fan in my 1993 318 (viscous?), when I start the van from cold the fan spins quite fast/hard, as the engine warms it seems to spin slower. Does the fan always spin no matter how warm the engine?

What is the 'normal' operation of this fan type, if for example I left the van idling until normal operating temp was reached?

Is there anything I can easliy check to make sure it's working ok?

thanks

Wilbo

 

The starting operation you described should only last for a few seconds to maybe a few minutes. My latest fan clutch will stay engaged for about 2 minutes or until 2500 rpms on cold start up. In the winter it does not kick back in very hard. But in the summer it will usually kick in at a stop light if I set a couple minutes and run for about 15-30 seconds as I take off from the stop and then kick back out.

The fan will turn continuously while the engine is on but at a greatly reduced speed.

For testing from my 97 FSM, 1) spin the fan when the engine is cold. If it turns freely with out drag then replace.
2) Drill a 1/8 hole in the top of the fan shroud (be sure to clear the fan blades) and using a dial or digital thermometer insert it in the hole, again be sure it will not get hit by the fan blades). Use a tachometer and run the engine up to 2400 rpms. Block the radiator or ac condenser with plastic or cardboard. When the temp of the thermometer reaches 190 the fan should already be engaged, engagement begins between 165 to 180, you will tell by the fan making a roaring sound.

DO NOT RUN THE ENGINE PAST 190 with the radiator blocked. Remove the plastic or cardboard. Now the fan should disengage between 135 and 175 degrees. The decrease of the fan roaring sound is the indication that it has disengaged.

If the fan does not respond in these perimeters then replace.