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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: m3talc0re on December 21, 2016, 12:41:25 pm

Title: Broke a new alternator belt. Not sure why....
Post by: m3talc0re on December 21, 2016, 12:41:25 pm
When I got the truck, it ended up eating the alternator belt that was on there. It was old and a little dry rotted, so I just chocked that one up to a bad belt. That was 2 weeks ago maybe? Well it just ate the new belt this morning. It looks like the belt stopped moving and was burned up. I can easily spin the alternator pulley, though. The belt was only $5, I don't think it could've been just because it was a cheap belt, but it's a possibility I suppose.. I dunno WTH the deal is. I'll look more when I get home. Any ideas though?
Title: Re: Broke a new alternator belt. Not sure why....
Post by: bd on December 21, 2016, 01:03:07 pm
...It looks like the belt stopped moving and was burned up....

Did the belt stretch and slip excessively?  Adjust the alternator belt tight enough that you cannot spin the alternator fan using all of your hand strength.  Then recheck it after driving for an hour or so.  Otherwise, figure out what locked up. 
Title: Re: Broke a new alternator belt. Not sure why....
Post by: m3talc0re on December 21, 2016, 02:25:29 pm
I did snug it up, then it started squealing again after a few days and figured the new belt probably stretched a little, so I tightened it up again. Hopefully not excessively tight
Title: Re: Broke a new alternator belt. Not sure why....
Post by: FlatBlack77 on December 21, 2016, 10:50:56 pm
can you post a few pics of your pulley setup?
Title: Re: Broke a new alternator belt. Not sure why....
Post by: m3talc0re on December 22, 2016, 06:49:37 am
What are you wanting to see? The way the belts are right now, there's a belt going around the crankshaft, water pump and power steering pulley. Then the other around the cs, wp and alt pulley. I don't think the power steering belt is supposed to go around three pulleys.. The sides of the belt look like they've been melted and the belt actually broke rather than burned through.
Title: Re: Broke a new alternator belt. Not sure why....
Post by: m3talc0re on December 22, 2016, 06:53:44 am
Here's a couple pics of the belt. I tried getting some of the pulleys, but you cant really see anything in them XD
Title: Re: Broke a new alternator belt. Not sure why....
Post by: bd on December 22, 2016, 08:44:10 am
We want to compare pulley diameters, belt alignment and routing among other things.  Rarely, a pulley configuration will cause paired belts to rotate at different speeds, burning, breaking or tossing a belt.  The situation can result from incorrect belt configuration or pulley substitution.  A lot of errors can accrue in 30 years.
Title: Re: Broke a new alternator belt. Not sure why....
Post by: m3talc0re on December 22, 2016, 09:51:36 am
I  can't really get my phone in there to get at useful pictures of the pulleys. Maybe this afternoon when I get home, I'll take the fan shroud off and see if I can get a better angle. I could measure the pulleys and make a diagram if that would help. I still think the alternator looks very very slightly out of alignment.
Title: Re: Broke a new alternator belt. Not sure why....
Post by: zieg85 on December 22, 2016, 11:22:50 am
I  can't really get my phone in there to get at useful pictures of the pulleys. Maybe this afternoon when I get home, I'll take the fan shroud off and see if I can get a better angle. I could measure the pulleys and make a diagram if that would help. I still think the alternator looks very very slightly out of alignment.

Pictures of the alternator specifically then.  Could be a "universal" that is wrong for your application.  I've seen it before and the lower bracket that spaces the alternator needs spaced out in order for the alternator to line up correctly
Title: Re: Broke a new alternator belt. Not sure why....
Post by: m3talc0re on December 23, 2016, 09:37:22 pm
Here's a pic of the alternator. When I spin it, it has a very small wobble to it, so I guess that's not really helping, either...
(http://i.imgur.com/PeQGSbf.jpg)
Title: Re: Broke a new alternator belt. Not sure why....
Post by: m3talc0re on December 24, 2016, 05:01:44 pm
Well, I put a new belt on there and while I was looking with the fan shroud out of the way, it looked like the bottom was towards the back a little too much, tucking in towards the engine. I put a small washer between the engine block and the little piece the alternator connects to right where the bolt goes into the block. Seems to have kicked it out a little and so far so good.. We'll see in colder and rainier weather I guess. I'll inspect the belt tomorrow, too. See if I see any excessive wear or anything.