serpentine belts not lasting long

#1
HI, I am new to posting to the Buick Forums here, though I have read many over the years and am grateful for much good advice. I have an 87 GN that I have had for almost 30 years, with high miles. Recently, I have had trouble with the serpentine belts crapping out. I have put three new ones on in the last month (not cheap ones either) and within about 5 minutes of idling, they somehow start coming apart on the engine side of the belt. I have checked all the pulleys etc. and don't see any way they should be getting cut. The only thing out of the ordinary I noticed was the tensioner sort of 'pulsating' when the engine idles low. Has anyone else had this type of problem? This is the first time I've encountered it.
 

Chuck Leeper

Waay too old!
Staff member
#2
Check the idler position. There are gauge marks on it.
If it's loose/spring tension low, it could cause the issue.
If the belt is too long, same thing.
 

earlbrown

runs with scissors
#3
Here's a side by side shot. On the left is acceptable with a tentioner in great shape, on the right is the desired result no matter what shape the tentioner is in.

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Notice the intercooler bracket and A/C nut for reference. The snug belt is close to the round bar, and the 'correct' belt has the pulley slightly overlapping the A/C nut.
 
#4
A loose AC compressor did the same thing to my belts. Under load the Compressor would swing out of alignment causing the belt to run on the crank pulleys lip. Lost the hood liner as the belts tore that up too.
 

Nick Micale

Tech Advisor
Staff member
#5
The stock size GM Parts belt for a 1986-7 turbo engine is 1618 mm.

I have seen aftermarket GN belts sold by auto stores can be too large, measuring up to 1642 mm.
 

DR BOOST

Technical advisor
#6
The stock size GM Parts belt for a 1986-7 turbo engine is 1618 mm.

I have seen aftermarket GN belts sold by auto stores can be too large, measuring up to 1642 mm.
There is also another situation that makes this problem worse. A non-stock alternator such as the commonly used LT1 alternator uses a smaller pulley which requires a shorter belt.
 
#14
Okay, here is a little bit more info....I did replace the alternator about two years ago, but turned in the old one to NAPA. NAPA man said it was a match for the stock one, so I trusted him. Also, as far as a pic of the tensioner, I have already taken the old shredded belt off, and have to get a new one before I can send a pic. Will try to get a Gates K6063 as mentioned. Thanks.
 

TurboBuRick

Moderator
Staff member
#17
Look at all the pullys. Look at the edge on the side the belt is being chewed up on. Look for one with a shinny metal edge. That could be a tell tale sign of the one causing an issue.

Also snap some pics