Is there a shock absorber / piston WITHIN the serpentine pulley system?

[mynamenumber]

Hi, I took my '05 ZHP to a local shop, just to see if they had any thoughts on a minor squeak / whistle sound that only appears for a short while after a cold start.

They suggested the serpentine belt and associated pulleys could use a service or replacement, and I'm happy to go with that recommendation. However, they called and said they had the car apart and ran into something "unexpected..."

He said that there was a shock absorber or piston or something within the belt / pulley system that had totally failed. "It's just flopping around loose in there, so we need to replace it" he says.

Anyone have a clue what part this actually is??

[wsmeyer]

Hydraulic Belt Tensioner. Part #8 here:

http://www.realoem.com/bmw/enUS/showparts?id=BW53-USA---E46-BMW-330Ci&diagId=11_2190

Or #21 for the whole assembly

[Vas]

Yes there is

[mynamenumber]

Interesting thanks very much.

Is there any potential issues that might be caused by that part failing, and having driven for some time with a failed Belt Tensioner?

I mean, I realize that a potential answer here is "a lack of a tensioned belt" so apologies if the question sets me up for a face-palm level answer :)

[danewilson77]

Interesting thanks very much.

Is there any potential issues that might be caused by that part failing, and having driven for some time with a failed Belt Tensioner?

I mean, I realize that a potential answer here is "a lack of a tensioned belt" so apologies if the question sets me up for a face-palm level answer :)
If you have the mechanical tensioner and it fails (or pulley fails), your battery light will come on, followed by loss of power steering, and ultimately engine overheat with blown head gasket. If some of the "tension" is not present (tensioner in some intermediate stage of failure), you can experience belt slippage, and may experience a loss of battery charging or engine cooling.

The hydraulic tensioner (shock absorber as you put it) is the upgraded design.

The AC tensioner is mechanical. No upgraded design for this however.

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[mynamenumber]

Thanks again to you all for the quick education on this part, and the belt system in general.

My local shop replaced both belts, all pulleys, and the hydraulic tensioner. So far, the whistle / whine / wail / squeak on cold starts is totally gone, but I'll keep testing.

Sounds like this was a worthwhile repair, and not at all something I'd want to "let go" for too long!

[johnrando]

Good news

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