I drive a 1992 Ford Sierra and now have a squealing sound coming from the fan belt. Would it be due to the water pump or alternator?
The mechanic says...
The most likely cause of squealing from a fan belt is incorrect tension (looseness) in the belt. However, first inspect the drive belt to make sure that it is not cracked or excessively worn, causing slipping on the drive pulleys. If all seems well in this respect, re-adjust the belt tension (by moving the alternator outwards, away from the engine, having first slackened the mounting nuts/bolts) to give approximately 1/2 inch (13mm.) of deflection under firm thumb pressure, applied midway along the longest belt run. Re-tighten the nuts/bolts after adjustment of the alternator position, then re-check the belt tension. Hopefully this should cure the trouble.
There’s an outside chance that the alternator or water pump bearings are partially seized, which would impose additional strain on the drive belt; check this aspect if the squealing continues after adjusting the belt tension.
