Join Date: Mar 2012
SixPack is offline
Re: Bad fan clutch?
A thermostatic variable fan clutch should not begin to engage when the engine is cool. If it does, the fan clutch is defective. A thermostatic fan clutch will slowly engage at idle and low speed when the engine is overheating and slowly disengage at high speed when the fan is not needed to pull air through the radiator. The fan clutch will not "lock up" suddenly and if it does, the fan clutch is defective.
A good fan clutch will slowly engage and slowly disengage according to the ambient temperature and you should not hear any fan noise. If you hear fan noise, the thermostatically controlled fan clutch is defective and is not functioning properly.
A fan clutch is defective it if the fan free wheels or if it locks up. A test of a fan to determine if it is freewheeling or locked up is to roll up one sheet of newspaper and stick it into the fan with the engine cool and idling. If the newspaper roll prevents the fan from turning, the fan clutch is defective. If the fan shreds the newspaper, the fan clutch is locked up and it is defective.
Last edited by SixPack; 05-18-2012 at 12:04 PM.