Serpentine Belt Coming Off - JeepForum.com

 
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post #1 of 7 Old 10-12-2014, 11:50 PM Thread Starter
aldersonfilm
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1998 TJ Wrangler 
 
Join Date: Jun 2012
Location: Pasadena
Posts: 277
Serpentine Belt Coming Off

Hey guys,

So my buddy was driving down the street when the dash lit up like a christmas tree and everything went haywire. Well turns out the belt has somehow come loose and shredded itself into three ribbons where became tangled in the fan and crankshaft pulley. Today we managed to get the old belt off an put on the new one on and fire it up, but after about a minute of running, the fan started clanking, so we shut it off. The belt was coming loose AGAIN and was riding on the edge of the alternator pulley. The fan was bent downwards, causing it to barely strike the crankshaft pulley. So something is outta wack somewhere. Anybody got an good ideas?

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post #2 of 7 Old 10-13-2014, 06:29 AM
M35A2
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1995 XJ Cherokee 
 
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It sounds like the fan bearing went away or the damper has separated. See if you can wiggle the fan.

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post #3 of 7 Old 10-13-2014, 08:41 AM
Paradise XJ
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1988 MJ Comanche 
 
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It is almost certainly your harmonic balancer (crank pulley dampner) separating. The pulley is mad of two pieces of steel, with a hard rubber sleeve in between them. The rubber shrinks and expands over time causing it to allow the two pieces of steel to "walk" in or out or both. The fix is to replace the whole pulley.

If it looks like this, it's toast...or almost toast. If it looks WORSE than this, you will not be able to keep belts on there and eventually could wear a hole in your timing cover. Climb under there and take a look.


1990 XJ Laredo - White & Chrome
1988 MJ Pioneer - Metallic Green and Black
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post #4 of 7 Old 10-13-2014, 02:10 PM Thread Starter
aldersonfilm
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Both of these are good suggestions, but if it's the harmonic balancer, why is the belt actually coming off again? It is slipping to the edge of the fan pulley and it is riding on the rim of the alternator pulley.
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post #5 of 7 Old 10-13-2014, 02:21 PM
AZ Jeff
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2014 JK Wrangler 
 
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Location: San Tan Valley Arizona
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Quote:
Originally Posted by aldersonfilm View Post
Both of these are good suggestions, but if it's the harmonic balancer, why is the belt actually coming off again? It is slipping to the edge of the fan pulley and it is riding on the rim of the alternator pulley.
Balancer has taller ribs on inner/outer edges to force belt into position. It's pulling the belt in/out and causing it to become shredded on taller edges.

AZ-Jeff
I don't own an XJ any longer, but I still think they are the best of all the Jeep products ever made. My XJ was my favorite vehicle in my 50+ years of driving.
So...I stick around and give advice.
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post #6 of 7 Old 10-14-2014, 12:16 PM
Paradise XJ
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Quote:
Originally Posted by aldersonfilm View Post
, but if it's the harmonic balancer, .
Crawl under there and look at the pulley

1990 XJ Laredo - White & Chrome
1988 MJ Pioneer - Metallic Green and Black
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post #7 of 7 Old 10-14-2014, 12:39 PM
Ajax1972
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1997 XJ Cherokee 
 
Join Date: May 2006
Location: North Carolina
Posts: 35
Cash money it's the Harmonic Balancer. I just did this last weekend after Old Blue left me on the side of the road on my way to the airport. There's some threads about changing it out and it took me (even after doing some STUPID things I really know not to do) only about 2 hours.

If you have the time, Amazon has a good price on a pulley and Gatorback belts. You'll need those two, an oil seal for about 8-10 bucks and a harmonic balancer puller. Look in the el cheapo tools at Harbor Freight or Advance. You'll need the 15 MM wrench for the idler pulley and a 3/4 socket for the bolt holding it on the front of the shaft.
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belt , fan , fan belt , serpentine

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