Have a 94 F250 XLT 4X4 with a 7.3 IDI turbo, 208,000 miles. Having issues with the belt wanting to move forward on the vacume pump pulley (Vaccume pump was replaced a year ago.) causing the belt to ride or shift forward on A/C compressor pully. Did chew up my belt of 2 years. (Lost 2 0f the 6 ribs of the belt. probably from riding over the edge of the A/C compressor!) Found questionable Idler and tensioner pulleys and replaced the Idler and tensioner pulleys today (Not the whole tensioner just the pulley wheel and bearing.) What could be causing the belt to move over? Belt and pulley alignment looks good after setting new Gates belt from Car Quest in place. even tried another cheeper belt from Rileys but no difference. Note Tensioner and idler are are at least two and three away in the sequence from the vaccume pump. Not fond of chasing symptoms and not finding the root problem to fix it.

Thanks for any help.
Rwelli1001
Las Vegas NV.

 

All i can say is there has to be a misalignment somewhere. Check the bearings in the vac pump and AC compressor clutch... and pretty much anything else for that matter. Also check pulleys for straightness and that the grooves are even and not worn to one side.

 

When the tensioner wears it tends to lean outward. Most of the time it will cause belt squeak before it gets bad enough to throw the belt. Grab your tensioner and see how much play you have (from front of engine to back of engine).

 

Well, Yesterday I purchased another Idler pulley from Ford Country here in vegas and purchased a new tensioner from Carquest (MFG by Gates.) at 1/3 the price. installd them one at a time and still no correction of my problem. Stopped and picked up a micrometer to measure the vaccume pulley to check for wear, out of round or bent but weather prevented me from doing any thing else today.

 

Well All fixed. The loose bolt (1 of 3.) attaching the bracket to the engine head and has the Vaccume pump, A/C compressor and Power steering accessories mounted on it, Apparrently also held a missing in action washer between the bracket and head. When I wedged a screw driver between the head and the bracket a bit the problem went a way. So I now have a new washer on the job. One of my clues was the fact that the bracket moved out a little bit when I removed the bolt that was loose when I found my problems. Thanks all for the help. PS Changed the Air filter and cleaned up the the air cleaner housing today also.

 

Good to hear you found the problem and great that you posted the fix.