[s-cars] Subject: Serp belt woes

Thu Jan 17 16:21:52 PST 2008

Aaron,

You must be a slow typist or a whiz at belt replacement.  :-)   
Especially doing it in the cold--a little snow in upper SC last  
night?  The old practice of carrying a spare belt for emergencies is  
not much help with this car if fails on the typical dark rainy night  
in the mountains with no shelter available.  It is challenging enough  
in the garage and just remembering how it is routed is a feat for me.

You did not mention the brand of belt you were using or where you  
purchased it.   The local flaps can match up a 6 rib belt by the old  
belt length or their parts catalog but the length may not be exact.   
They seem to think a few mm doesn't matter since they all use a  
tensioning system to take up the slack, usually longer since shorter  
may be too difficult to install.  Much in the same manner they will  
sell you spark plugs because they are physically the same size but  
may not be a good choice for your engine.  When buying online, I buy  
two to spread out the shipping cost or get the minimum order for free  
shipping, and have a spare at home.  There are 3 S6's on my block  
that might need one.

I changed a compressor because of the roar and because I thought it  
did not cool as well compared to other S6's.  The new one cools the  
same and makes as much noise, i.e., no change except to lighten my  
wallet considerably, so I would evaluate the a/c on performance.  I  
think your belt problem lies elsewhere if you can turn the compressor  
by hand with the clutch engaged (no belt).  It does take some engine  
power to operate the compressor.  I put the shipping plugs in the old  
compressor and its  been on the shelf for a year if you want it.

I would clean the tensioner spring portion as much as possible and  
lubricate with a high quality grease.  Those I have seen failed are  
badly corroded and fail catastrophically, throwing belt parts  
everywhere.  Since the pulley spins freely by hand I also think the  
tensioner is fine, and the noise you hear is coming from elsewhere,  
just transmitted to the tensioner area.

Check the fan clutch to ensure the fan freewheels when it is cool and  
does not wobble excessively on the bearing in the support.

On Jan 16, 2008, at 11:01 PM, Aaron Ryba wrote:

> Thanks everybody for the input.
>
> When I ran the car without the tensioner I mean I removed it and  
> the serp belt so no accessories were running, only the timing belt.  
> I wanted to make sure it wasn't the TB tensioner/bearing which it  
> wasn't.  What is weird is that I also ran the engine without the TB  
> cover but WITH the tensioner and belt and the same noise persisted.  
> The noise which I thought was the sound of the tensioner roller  
> rubbing against the TB cover (wear on the cover to prove it)  
> persisted without the cover. I didn't put a stethoscope on anything  
> but I am fairly certain the rumbling noise is coming from the  
> tensioner bearing and not the other pulleys. I'll try the DIY  
> stethoscope with some rubber tubing this weekend. I haven't yet  
> tried to freely spin the other pulleys, I know the steering pump is  
> spins well, it could be the AC compressor. I'll have to look when  
> its not snowing outside. I would describe the noisy compressor when  
> running to be like a "jet
> engine or turbine sound," so it seems like it is failing like others
> typically do.
>
> With the serp tensioner out of the car the bearing roller turns  
> just fine and without noise or problem and there isn't any play in  
> it. It will turn about 4 or five times with the spin of my hand.  
> The reason why I think it is a belt problem is because the  
> tensioner seems to be fine. The spring is still very firm as  
> evidence by how much force is needed to lock it into place for  
> removal. From reading in older posts it seems like when tensioners  
> fail it is the bearing and not the spring. I assume a sticking  
> bearing will improperly load the spring and hence the cracking  
> noise.  I agree that even with a stretched belt, the slack would be  
> taken up with the tensioner however the cracking noise from the  
> spring in the tensioner only happens when under load from idle when  
> doing a three point turn or pulling away from a standstill so  
> perhaps it is only at these moments of low RPM when the slack in  
> the "stretched" belt is enough to overcome the tensioner spring. It
>  seems like when the RPM is raised there is more tension on the  
> belt and hence the cracking noise goes away. I don't know if that  
> even makes sense. Oh well.
>
> The secondary scraping rumbling noise (i assume from the bearing  
> itself or from rubbing against the TB cover) happens all the time  
> and is loudest around 2k rpm. Not a very loud noise but noticeable  
> even from inside the car. These noises all seemed to gradually get  
> worse over time,  and the fact that I started to use the AC over  
> the summer for the first time since I replaced the tensioner and  
> belt makes be think it is the AC which ruined the belt. Due to the  
> AC compressor not being totally seized but just harder to rotate  
> maybe it is possible that put the undo stress on the belt gradually  
> which would otherwise have heated up and shredded had the  
> compressor seized up instantaneously.
>
> I guess the cheapest solution right now is to throw on a new belt  
> to the tune of about $25 and keep my fingers crossed. If that does  
> it I will keep the AC off till I can fix that. The non-AC spec belt  
> is a good idea, I thought of that as well but being in SC here for  
> the summer I'd rather pay for a new belt every year than go without  
> the AC, granted the compressor lasts much longer that is!
>
> All this typing and I could have already replace the belt by now.
>
> Aaron Ryba
> noisy 95 S6
>
> ----- Original Message ----
> From: Tom Winter <tom at freeskier.com>
> To: s-car-list at audifans.com; aaronryba at yahoo.com
> Sent: Wednesday, January 16, 2008 10:00:30 PM
> Subject: Subject: [s-cars] Serp belt woes
>
>
> Aaron - I'm no expert, but I'd expect the tensioner to last longer  
> than
> that. I did have some noise issues from a serp belt, not a rattling,
>  but it
> was making noise (and then broke, solving the noise problem! LOL!).
>
> Perhaps you'll get lucky on this one and it will be just the belt. You
>  said
> you ran the car without the tensioner - I'm not sure how you did  
> this -
>  and
> there was no noise under these conditions. But I'm wondering if the
>  other
> pulleys in the system aren't worth taking a close look at. Perhaps  
> when
>  the
> belt is under tension, they are the source of the problem. Just a
>  thought. .
> .
>
> Good luck.
>
> Tom
> '95 S6 Avant, waiting on parts
>
>
>
>
>
>
>
>        
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