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Fan belt rides back on A/C pulley when running

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1.2K views 12 replies 3 participants last post by  Dew  
#1 ·
  • Hello, I have a 02 gmc envoy with the 4.2 i6 and 187,000 miles on it. Ok here is my issue, when I start the engine the fan belt slides to the rear of the water pump pulley and in turn slides to the rear of the A/C pulley. I have replaced belt tensioner, idler pulley, belt, water pump, water pump pulley and still the same problems persist. I finally just put on a shorter belt to bypass the A/C for now. Even with the shorter belt you can still see the, belt move back on the water pump pulley when engine is started but it works for now. I don't know what to do or where to go from here. Is it the a/c clutch or am I missing something. Any help is greatly appreciated. Thanks
 
#3 ·
Hopefully you bought this new and know the history. Has the alternator or power steering pump been replaced? Sometimes a missing or added washer can throw the alignment off. What is just before the water pump re: the belt routing?

Do get pix for RayVoy. He is a past Envoy owner and knows the accessory drive for it.

Ted
 
#4 ·
On this vehicle (with the L6), only one belt.
I probably have a pic of the belt config; but, so do you. It's on the rad support.
While your taking pics, send one with the belt moved off the pulley center.
 
#5 ·
Hey guys thanks for the reply, the belt is routed correctly, the belt configuration is on my air intake box. I have a video of what it does on my phone but don't know how to upload it on here. Do y'all know how to upload it?
 
#7 ·
These are the pics of the short a/c bypass belt. I noticed something the other day, when the belt goes down from the alternator to the idler it curves out a little and when it goes down to the a/c it curves out a little also. Another mechanic I talked to about it said put a straight edge on the flat spot on crank and rotate the straight edge to all the pulleys to make sure they're all inline, but they are not. I don't know any other way for them to be though seeing I cant move them back. Ugh makes me want to pull out my hair! lol Any way thanks again!
 
#8 ·
I didn't want to see the routing diagram to suggest you had the belt on wrong, I wanted to see which pulleys were groved and which were smooth.
Your buddy with the straight edge idea is on the right track, that is the correct way to check alignment.


When you checked with the straight edge, what pulleys were not touching?
 
#9 ·
Oh ok I wasn't trying to be a butthead or anything just extremely frustrated. I do appreciate your help GREATLY.

I used a straight edge again just to double check myself and here is what I found.

With straight edge flush against the face of crank there is about 1in maybe less but no more between the edge and power steering pump.

Between the edge and alternator looks to be about 1in. also.

Between edge and a/c clutch (the nut right in the center) there is about 1/4 in.

But also wanted to ask you if the outside bolt hole on the alternator is supposed to be elongated? Could that be the issue? Maybe I didn't have it tilted up in the front enough?
 
#10 ·
The tilt would be easy to check, with the straight edge in place, the top and the bottom of the pulley should be the same distance from the straight edge.

I don't recall there was an elongated hole in my alternator. I do recall having it off and I think all holes were round.

It sounds like the ac compressor is the problem. In the pics you sent it appears as though the belt is staying straight.

Has the compressor ever been off?
 
#11 ·
Yea, the compressor was changed with a new one back in October when we bought the envoy. The belt I have on in those pics doesn't go around the a/c or idler I just bypassed those for now so I can get it to run.

I did find the bottom alternator bolt was missing. So I'm trying to get it in now.
 
#12 ·
Well guess what, got the bottom alternator bolt in and solved the belt issue! Doesn't squeak or anything! It'll work until I get the full length belt so I can have a/c.

Now, next problem I have is heat gauge isn't wanting to work right so I ordered a new one from rock auto put it in and now the heat gauge don't want to work at all! So I'm going to send it back and get another one and hope that fixes it.
 
#13 ·
Just reinstalled the old temp sensor after cleaning the brass part with some sandpaper and now it works better than the new one! Who knew! I'm gonna run it like this for a couple days and see. Thanks for all the help!

If I have any more troubles (hopefully not) I will check back with you! Thanks again !!