Serpentine belt question

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salinity
Posts: 40
Joined: Tue Oct 17, 2017 11:28 am
Location: RI

Serpentine belt question

Post by salinity »

Getting to know this car a bit under the hood...

While under the hood, I noticed I could put quite a bit of deflection on the serpentine belt (at least an inch). What is the typical deflection in the middle of the belt? I'm used to 1/4" or so on my Cherokee. Is there a way to tighten the belt, or is the tightness dictated by what I assume is the hydraulic tensioner? And how does one know when the tensioner is bad? I didn't notice any leaking fluid.

Thanks.
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2007 Base
andrewclaus
Posts: 482
Joined: Tue Oct 03, 2017 6:38 pm
Location: Golden, CO

Re: Serpentine belt question

Post by andrewclaus »

I have not changed the belt yet on my "new" '07 but will soon, so I looked this up and couldn't find a deflection spec. It sounds like the tensioner is supposed to take care of it, but 1" sounds excessive. I would suspect a faulty tensioner and I hope one of the old hands will jump in here soon. My car is out of town right now so I can't check mine.

It looks like the part is readily available on eBay etc, so perhaps that means it does fail occasionally.

In the meantime, if you don't get a squeal when you put load on the alternator, A/C, or PS, and if the belt isn't completely trashed, I wouldn't worry too much about it.
ehoff121
Posts: 756
Joined: Mon Feb 26, 2007 12:19 am
Location: Conn.

Re: Serpentine belt question

Post by ehoff121 »

The belt tensioner is the only thing you move to replace the belt. If it's working quietly and the belt isn't cracked or slipping, it's fine.
2005 Pontiac Vibe AWD - Platinum
salinity
Posts: 40
Joined: Tue Oct 17, 2017 11:28 am
Location: RI

Re: Serpentine belt question

Post by salinity »

Thanks for the responses. The deflection does seem excessive, and the hydraulic piston does show some signs of wear, but there’s no noticeable noise or wear as of yet. I’ll probably try to get thru the winter and put it on the spring to-do list (prioritizing snow tires right now).
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2007 Base
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joatmon
Posts: 10018
Joined: Fri Mar 21, 2003 5:19 am
Location: SMC MD

Re: Serpentine belt question

Post by joatmon »

on my 03, pressing down on the top span of the belt (with the engine off, of course) it seems relatively easy to get an inch of deflection. I agree with ehoff121:
ehoff121 wrote: If it's working quietly and the belt isn't cracked or slipping, it's fine.
If you do replace the belt, throw the old one in with the spare tire for potential emergency use (unless its broken)
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ColonelPanic
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Location: South Central Indiana

Re: Serpentine belt question

Post by ColonelPanic »

Just went out and checked ours - same here with the deflection. This is with a relatively new belt and tensioner (replaced both last year with GM parts.)
03 Vibe base. Born 10/14/2002 06:07 AM
Auto, Moon & Tunes, power package. 143k
Neptune/dying clearcoat/primer grey. :lol:

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