Question QUESTION: what is the loud squeal I hear in the pump that goes away at higer RPMs
ANSWER: Hi Jack -
That is probably a loose belt that needs tightening. You did not mention what model/year of your vehicle or whether it has A/C or not, but check all the belts for proper tension. A good test is to spray WD40 on the belt while it is making noise. If it goes away, then that is the belt that needs tightening.
Hope this helps -
calvin
---------- FOLLOW-UP ----------
QUESTION: after checking all belts the squel persists could this indicate a problem in the fan asembly?
Answer Hi Jack -
Did you replace the belt after trying to tighten it?
If so, and it still squeals, spray the belt (while it is running) with a little WD40. If the sound goes away, it is definitely the belt.
If the souds stays, then check your idler pulley or alternator bearing.
