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Unread 12-19-2012, 10:27 PM   #1
WJ_BEAST
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how tight is too tight for a serpentine belt?

93 zj 4.0

I keep getting a random squeal so I tightened my belt and it was fine for a day, then realized when my ac pump kicked on it seamed to come from there.but then today when I drove it it sqealed a few randon times without the defrost kicking on the ac pump.so do I keep tighting my belt or do I assume I need a new fan cluctch assembly or whatever that part of the pump is called.it has a newer gator back belt.

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Unread 12-20-2012, 12:50 AM   #2
AVR2
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The rule of thumb I use for manually-tightened serp belts (and which I learned about here) is that you should be able to twist them no more and no less than 90 degrees at the tension test point. I've no idea how well that relates to the actual tightness spec, but it's worked for me for years
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Unread 12-20-2012, 03:59 AM   #3
KoreaZJ
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Quote:
Originally Posted by AVR2 View Post
The rule of thumb I use for manually-tightened serp belts (and which I learned about here) is that you should be able to twist them no more and no less than 90 degrees at the tension test point. I've no idea how well that relates to the actual tightness spec, but it's worked for me for years
Where is the "tension test point"...?
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Unread 12-20-2012, 04:44 AM   #4
AVR2
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Halfway between the upper idler pulley and the PS pump pulley :

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Unread 12-20-2012, 04:48 AM   #5
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i assume there is a torque spec,do you have a haynes or chilton?
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Unread 12-20-2012, 04:57 AM   #6
ratmonkey
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Theres a gauge for belt deflection. His method is close enough.
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Unread 12-20-2012, 05:15 AM   #7
AVR2
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i assume there is a torque spec,do you have a haynes or chilton?
The tension spec is in the FSM and Haynes, but accurate tension gauges are expensive and even most of the auto shops around here don't have them, since most engines have had automatic tensioners for so many years now. The twist test, or the thumb deflection test, will work fine in most cases. I certainly have no problems with belt slippage and it doesn't seem to be over-tight either.
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Unread 12-20-2012, 08:02 AM   #8
WJ_BEAST
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How would I tell if its the ac clutch/bearing or not. I ve only been able to make it to the front that one time when it was doing it for a few seconds.otherwise I cant seem to make it do it .it just likes to randomly do it at embarrassing moments lol
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Unread 12-20-2012, 06:01 PM   #9
jeepinbassist
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Mine's been doing the same thing. It only happens when it is really cold out and the engine is still warming up. My squeal is coming from the AC. I know the clutch froze up and had to be replaced about a year before I got it, and i know that is was a JY compressor. So it seems like it is starting to do it again. I'm not sure if replacing the bearing could save it or if the whole thing is shot.
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Unread 12-20-2012, 08:24 PM   #10
jtackerman28
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Chances are its isnt the ac pump its the alternator
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Unread 12-20-2012, 09:55 PM   #11
ZJMTL
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Try cleaning your belt on both sides with a small wire brush/cleaning brush while the motor is on (be careful of the clutch fan, and watch your fingers in general).

Then when you're done that, rub a 1'' wide dab of dialectic grease on both sides of the belt in one spot.

I read this somewhere else on JF. Apparently dirt on the belt + cold days usually results in a squeak. In my case it has worked and cured squeal for long periods of time.
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