serpentine belt tensioner for early 1997 A8Q
 

I'm confused about the ribbed belt tensioner. 8/96 build date, Canadian A8Q. I think my tensioner is going, since the belt squeals for a few minutes on cold startup only. I can make it louder or softer by turning on or off the A/C (few month old compressor). The belt itself is maybe a year old. Looking up a tensioner, part # 077903133E (077903133C) comes up. I see prices from over $200 to $10.

https://cimg3.ibsrv.net/gimg/www.aud...18fb3a04b8.jpg

The picture looks strange to me, since mine looks like this installed on the car (using silverd2's photo from thread https://www.audiworld.com/forums/a8-...moval-2820909/ .

https://cimg0.ibsrv.net/gimg/www.aud...856d514248.jpg

Is the 1st picture above of the right part? Where is the large silver cylindrical part hiding in silverd2's photo? And it seems like the 1" thick cylinder just left of the allen wrench just above seems to be doing the tensioning, no? I seem to recall it pushing in easily but taking a long time to come back out, when I had the front off the car.

and what is the bent little rod sticking through?

https://cimg7.ibsrv.net/gimg/www.aud...8f15457823.jpg


Also, the various ebay offers selling 077903133E seem conflicted about what it fits.

Have a look here:
https://audi.7zap.com/en/rdw/audi+a8.../9/903-903080/

If it's the same as the facelift part you can put on an idler from a Hyundai 2.7L DAYCO Part # 89010 or GATES Part # 38027, around $15. The size appears to be 82mm x 17mm x 25mm (or 26mm) Application (among others) 2001 HYUNDAI SANTA FE 2.7L V6

This is cheaper than buying the whole tensioner assembly. It's important to replace there before the grease migrates out and they run dry, overheat and fall apart. The static idler on the LH side of the engine lasts a lot longer but I'd replace it by 150K at least also. Both of these can be repacked with grease and they'll last a lot longer but in my case the tensioner roller was pretty worn and seemed good to replace around 150K.

I have the Hyundai roller on both of my D2s, many miles, no problems.

so the original audi part fits '97-'04, but the aftermarket units only '00-'04?
 

I'm getting confused as to what years the 077 903 133 E serpentine belt tensioner fits. I can't find an aftermarket listing for a serpentine belt tensioner 077 903 133 E that is explicitly listed to fit the 97-99. Many of them say only 2000 - 2004. But the same part number sold at the dealers is advertised to fit the pre-facelift ('97 - '99) models as well as the '00 - '04. https://audiparts.audiwilmingtonde.c...QtMmwtdjgtZ2Fz

6 items come up on a search for the part number at ECS Tuning https://www.ecstuning.com/Search/Sit...77_903_133_e/; ranging in price from $45 to $137. 4 of them are listed as aftermarket, and 2 as "genuine VW/Audi". One of the genuine parts says "This part does not have vehicle applications yet." The other 5, including the other "genuine VW/Audi", all come up as "fits from the 2000 model year".

There also seems to be some confusion on the FCPEuro website https://www.fcpeuro.com/products/aud...03133e#fitment, where it has an advertisement - "Wait, save with aftermarket!", with a link to the Febi version, which then comes up as not fiting. FCPEuro doesn't seem to understand the discrepancy either.

Does this make any sense? Maybe some mistake in some database got propagated through the entire industry?

And how can aftermarket ones be going for as little as $10 new on ebay? https://www.ebay.com/itm/077903133E-...cAAOSwUalb~gkT That one supposedly fits 2003 - 2004. Who actually makes these? There can't be that many factories cranking these things out, can there? (Two of the choices in timing belt tensioner dampeners are ones under the Stabilus and the INA names. I chose the INA, and got a Stabilus in an INA box. There's more to the older parts supply chain than meets the eye.)

Audi wants $91 for each roller. Rockauto has them for $13 or $14, plus shipping. Advance wants $20. But then there are a number of entire tensioner assemblies on ebay for as low as $10, though I gotta figure out if they'd fit.

Is there any reason to think the tensioner assembly would go bad? Broken spring or bad shaft is the only thing I can think of. Maybe I should try to take mine apart.

The spring could fail if there was a problem with the metallurgy. If the same bozos that made the left rear suspension spring on my A8 made the one in the tensioner...

What happened to your spring?

My LR suspension spring broke, this has happened to others. I have not had a problem with a serpentine belt tensioner, I did replace the idler and tensioner roller though. I could see the spring going bad in the tensioner. It can happen with a spring.

So the spring-loaded tensioner itself was fine. (I just did the timing belt.) The belt tensioner damper was seized. The squealing is cured now, I suspect by the new damper, though I did also put a new belt on it. Thanks for the comments.