OK guys, I have searched over the forums, and if this issue has been addressed, Please let me know. My son has a 1986 F250 XLT Lariat with a 351W, AC and Automatic. It has approx 150K miles. Recently, he complained the engine was whining and squealing at High RPM.
I looked at the belts, and replaced. I went through several process of elimination attempts to verify the squealing was coming from the Power Stearing Belt/Pulley. I had tried different belt tensions to try to eliminate.

After my help, or lack thereof. he got a wild hair and changed the pump. The squeal is still there. Sometimes at start-up others once he gets the engine to 28-30,000 RPM. The belt alignment is clean and straight. My only guess is the Pulley/Sheave is worn on the inside. If I run a finger inside, there is a subtle groove worn into the metal. Is this a likely cause for "Belt Squeal"? I really do not like to use belt dressing, but the kid did and it stops for a few minutes when he uses it. Once it gets hot. I think it evaporates. but it has left the belt sticky to the touch.

Is there a easy cure for the problem. I am not sure changing the Pulley would make it stop. Plus I am having a hard time locating a "NEW" one. A junkyard could work, but it may be just as worn.

Any guidance would be appreciated. Coles DAD

 

You may want to check the fan clutch for proper operation. I had belt squeal at higher RPM's and found that the fan clutch was worn causing the engine to turn the fan at higher revolutions and straining the fan belt.

 

I had an 85 with a 351w h.o. that had a belt squeal problem. Check your fan clutch first, if it's good then you might want to think about switching to a serpentine pully system. I did and it solved my problem. There should be plenty left in the wrecking yards. Just be sure the donor vehicle didnt take a front impact.

 

if you go to a serpentine system make sure you get the water pump of the donor motor as it is a reverse rotation pump.

 

I doubt we will go serpentine, the fan clutch appears OK, what is a good test for the fan Clutch. (just to be sure)

 

Rev the engine. If it speeds up like it should, then its ok. If it hardly turns when reving the engine it's bad. Also try to wiggle the fan. If it wiggles it's bad. If you can spin the fan freely(little to no resistance) it is bad.

 

Does the fan turn freely with the engine off and cold, when you turn it by hand? Try wiggling it back and forth. If you get sideways movement, the bearings could be worn.

 

Beat me to it.

 

sorry! lmao