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  #11  
Old 29th March 2020, 08:41 PM
Audifan Audifan is offline
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It's crazy how much these OEM tensioners cost This is another maintenance job that my car needs. Should I also buy new chains when replacing the tensioner?
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  #12  
Old 29th March 2020, 09:59 PM
spannerrash spannerrash is offline
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I fit new chains when I did mine. I think they were only £50 each so I just did them while I was in there. The whole job cost me about £1500. New tensioners, chains, gaskets, Camshaft oil seals and I also used new Camshaft bearing cap bolts. Not sure I really needed to do that but was unsure if they were "torque to yield" so replaced them just in case.
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  #13  
Old 8th April 2020, 10:06 PM
Versace Versace is offline
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What´s the OEM price anyway for a tensioner?
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  #14  
Old 8th April 2020, 10:40 PM
MikkiJayne MikkiJayne is offline
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List price is about £750 each.

The bolts are specified as single-use simply because they are torque-to-angle, but they are not torque-to-yield. They'd pull the thread out of the head far before the bolt stretched. I changed them on the first couple I did, then measured the new bolts against used bolts and found they were identical so I re-use them now.
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  #15  
Old 9th April 2020, 09:02 AM
spannerrash spannerrash is offline
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I never did get around to it but it may be worth someone doing some research to see if there is anyone out there that can repair these things. I think we're OK for a little while but it's only a matter of time before these (like many other D2 / D3 parts) become NLA.

If no one picks it up I'll start having a look once I finish my current job list.
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  #16  
Old 9th April 2020, 09:51 AM
MikkiJayne MikkiJayne is offline
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There's a chap in Lithuania who can do it. Sean and I have been talking to him about doing a set for both our 3.7s, but he is not great at communicating and given the current situation its stalled. We'll pick it up again when life returns to normal I think.
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  #17  
Old 26th July 2021, 09:17 AM
ThisWayUp ThisWayUp is offline
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Looks like I'm in the market for a replacemnt tensioner.

As part of my refresh project, I decided to inspect the top end. The passenger side tensioner looks like this.



If I'm not mistaken then I'm assuming this is the cold start interlock that's failled possibly due to the filter mesh disintegrating?

The driver's side looks quite health by comparison.


Looks like there are a few options for replacements, but I have no experience of how good or bad these might be.

Top of the tree: Audi at immense expense.

Autodoc has the following available:
Ridex - £163.00
Esen - £165.00
Vaico - £382.00

Not exactly 3 brands that I have any experience of.. Any thoughts?

Thanks
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  #18  
Old 26th July 2021, 11:09 AM
MikkiJayne MikkiJayne is offline
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In 100% of my experience it's the driver's side tensioner which fails first, and its really only possible to tell what state they are in when they are out of the engine.

I'm not entirely sure what you're seeing on the passenger side - normally the exhaust cam jumps forwards when the belt is removed due to the position of the lobes acting on the valve springs at TDC. Perhaps it jumped forwards and took the inlet cam with it, and then you wound it back and it hasn't tensioned the chain?

There are two failure points in the tensioners. First is the cold start pin - if this is working then with the tensioner removed one of the shoes will be locked in place and the other will be under some spring tension. If this isn't working (ate the gauze) then both shoes will move. This isn't fixable and needs a replacement. Its always the driver's side which goes first as the pin is at the bottom on the driver's side so the gauze drops down the inside and gets pushed through the pin. On the passenger side the pin is at the top so rarely fails as the gauze drops to the bottom and never gets to the pin.

The second failure mode is the non-return valve in the base of the tensioner which provides initial tension on startup. A good tensioner will not leak oil out of the base when removed (non-return valve seating properly) whereas a bad one will constantly dribble oil, especially if you work the shoes up and down. This will cause a little rattle on startup but is generally acceptable. Again, usually the driver's side first but for no obvious reason this time. It looks from your pic that this may have failed on the passenger side, but you can't necessarily see it on the driver's side as the tensioner is the other way up.

The RS6 guys seem pretty convinced that the Vaico units are in fact the original Audi units but without the £300 Audi rings. Chances are next time I need a set I will go with those.

I've also heard that the BGA units from GSF are also the Vaico units for £150 trade, but as I don't have an account with GSF I've been unable to verify that. BGA don't list anything for the S8 but they are the same part as the A8 4.2 which is listed. Retail from GSF is the same as the Vaico from Autodoc though.
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  #19  
Old 26th July 2021, 11:55 AM
ThisWayUp ThisWayUp is offline
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Thanks MJ - That's really useful info.

If I recall, we opened up the cam cover and the passenger side was sitting slack. The cam belt is still on and tensioned at this stage.

The engine was then wound round, which naturally brought that top run of the chain into tension. Currently the triangle and square markers align, so it's not skipped as yet. It sounds like I should buy a set of tensioners Vaico/BGA and the associated bits, and then strip it and see what I have, and then decide what to replace at that stage - If I can get the tensioners at reasonable money then Id be as well to do the lot.

I've not used the car in recent times, but I was in the habit of starting it once a month and on occasion I'd get a persistant ticking, which I assumed was a lazy hydraulic tappet. Perhaps not?

I'll update once I have it removed, and figure out what I have.
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  #20  
Old 26th July 2021, 12:23 PM
MikkiJayne MikkiJayne is offline
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Ok. Its pretty unusual for the chain to be sitting slack like that then, so something may well have failed on that side.

I would pull the tensioners and inspect them before buying replacements though, just to understand what is going on. Do you have the tensioner compressor tool? If not I can send you one. New pads and tensioners do come with the tool, but thats not helpful if you want to pull them before buying new bits

A regular ticking is usually a lazy tappet yes. They often come back with an oil change and some heat in the engine.
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