Accessory belt derailing

[jlopezpe]

I just installed a new serpentine (accessory) belt in my 1990 W250, but it becomes "derailed" at the air conditionar compresor by about 1/4 of an inch in the inboard side. I have relocated the belt in all the pullies on all the accessories and the problem repeats itselfOo. This never hapenned before. It just started with the new belt. I checked the belt before installation againt the old one and they seem the same. What gives?:{ By the way thank everyone for helpping me with my brakes issue.

 

[RDusch]

Mine started doing that when my water pump went out, the water pump bearing becomes worn and the pully rides at an angle walking the belt off 1 groove at a time, if it starts chewing the belt up you can get small belt pieces down in the AC clutch and the'll keep the compressor clutch from engaging.



Rick

 

[ScottB]

Mine has done that twice. Once it was the waterpump and the next time it was the belt tentioner. Check both, as to why it did that when you put a new belt on I don't have any idea. Hope you get it figured out.

 

[JLEONARD]

I guess you need to check out the water pump and the tensioner.

I know from my experience with the 6b in marine applications that the tensioner is considered a very weak link in the system. Perhaps it went over the edge when you pulled it back to get the new belt in place.

 

[3dracer]

belt problem

I had this problem on my 92. After 2 or 3 belts, I figured out my problem. The ac compressor is bolted directly to the block,,loosen up the bolts and pull up on the back of the compressor while you tighten the bolts. There is enough "play" in the bolt holes that makes the belt run off. . This has fixed mine and have put several miles on her since the fix. .

 

[jlopezpe]

Well, 3dracer proved to be right. After removing the belt I checked the water pump by moving the pulley. I found no slap on it and it moved smoothly. When I checked the air compressor I noticed that the top bolt was not bolted all the way in. The bottom bolts were not very tight either. The top bolt turned out to be too long. A proper lenght top bolt and and 3Dracer's suggestion fixed the problem

 

[3dracer]

To jlopezpe........

Glad to help out,,,save that shop bill for more add on goodies, heah??