Aftermarket cam tensioners
 

Hi all,

Has anyone used the aftermarket cam tensioners for the 40V? I just got a price of £478 from TPS which is totally untenable, and unfortunately our hosts don't have any used ones at the moment.

Background - lumpy idle, CEL for cam position sensor, compression 10-11 bar on 1-4, 12-13 bar on 5-8. Opened up the cam covers to see the 1-4 bank tensioner jumping up and down when I rotate the engine by hand. Seems that the top of the tensioner is loose and the bottom is locked solid so the chain is slack and the inlet cam is jumping around.

Very :-( at the moment. I don't want to spend £1000 on tensioners to find there's valve damage, but very wary of putting potentially crappy Chinese bits inside the engine.

Thanks
MJ

My advice would be to go oem regardless of cost.
Yes, a8's are expensive to own.

Also, get it checked out by an expert to be sure if its the tensioner and which part of it thats faulty. I'm not sure you can determine faulty operation in the way you describe. There is a solenoid which is a part of the tensioner mechanism and this has no power going to it when you are rotating the engine by hand.

At least, follow the ElsaWin audi workshop fault guide for the tensioner to test it in the correct way.

IIRC without the engine running the chain will be slack anyway, the tensioners need oil pressure which requires a running engine.

Do you get any constant rattling from the camchain area when the engine is running, do the tensioner pads show any sign of wear or failure visually?

My take on aftermarket parts

They don't always fit correctly, they don't work as effectively as original parts, they don't last the test of time

Thanks for the thoughts guys. I'm comparing the two banks to conclude it's faulty. Turning it over by hand the chain for 5-8 is taut on the tensioner and the cams turn smoothly. 1-4 however the tensioner jumps up way higher than the other one as the inlet is about open a cylinder, then as soon as it's past centre the cam jumps round off the rollers and the tensioner drops down.

This is what I found when starting to investigate the cam position sensor error:

http://www.corradov8.com/pics/ohfck.jpg

Timing belt changed without the damper :mad: Tightening the belt and setting the cams with the bar I get bank 1 is about 2 bar short on compression compared to bank 2. I'm really hoping its this dodgy tensioner causing the lost compression rather than many bent valves.

I also discovered that the impeller has fallen off the crappy aftermarket water pump and started machining its way in to the block. Temperature was fine on the drive home from picking it up though (and it drove fine apart from a vibration at idle and an occasional misfire) so I'm hoping a new pump will be ok.

If it was just the tensioner then I'd buy a genuine one without question, but with the engine potentially fubar I'm not going to spend that on it until I know the engine is still ok. I think I'm going to put an ebay tensioner on it to start with to see if it runs properly and then change it out for a genuine one if the engine is ok. That way I've only wasted £100 and some time, rather than £500 if its toast.

In case anyone recognises the stupid orange pulley, yes this is the one from ebay. I bought it based on VCDS saying the cam position sensor was open circuit and it driving fine. No idea it was potentially going to need a whole new engine :mad: Bent valves would actually have been cheaper. Stupid stupid stupid.

Oh, and to add insult to injury, the really tricky bolt for the oil cooler under the manifold is totally rounded out so I've got to take the whole damn engine out to change the plastic pipe. Hard to convey how fed up I am with this car already. I've been looking forward to getting another D2 for ages but I'd have been better off just setting the cash on fire.

If your parts are coming from TPS do they not meet VAG spec?

Could it have jumped a tooth on one of the cams

Rather surprisingly it didn't jump a tooth at all - when I pulled the tensioner tight and locked the crank the cam bar was just a mm or two off fitting in place. The belt had been fitted by marking the pulleys rather than using the proper tools. Its amazing its not completely destroyed tbh. POs have been driving like that for up to 5000 miles since the belt was done.

I've got a £100 ebay tensioner on the way to test. If I get compression on 1-4 with that in place (and the cam stops jumping about) then I'll spend the £500 on a genuine one from TPS. If the valves are bent or there is other internal damage then I'll be looking for another engine and I've only wasted £100 instead of £500. The engine is out now anyway, since its utterly impossible to get to that rounded off oil cooler bolt with it in the car. I'm going to do a complete re-seal on everything and clean up the bay while its out, and I can compression test it on the floor.

This car is like a mistreated horse - its now kicking the crap out of anyone who comes in range :(

I hope its just the tensioner and is easy to fix, they are lovely cars when in good working order.

If you haven't got one already, one of these cheap little cameras should fit down the sparkplug hole may have enough resolution to confirm any contact marks on pistons.

Also worth scanning with VCDS to see what error codes come up, and to see if its recording any actual missfires.

http://www.ebay.co.uk/itm/USB-Waterp...cAAOSw~gRV1BSs

http://www.ebay.co.uk/itm/2m-High-Re...8AAOSwFnFV~21H

Let me know if you want ElsaWin instructions for tensioner testing, I can easily copy it to PDF

Ooh thats a good idea - I've got one of those for drains. I'll have a look tomorrow. I have Elsawin thanks :) I love how the tensioner procedure starts with "Remove engine" :rolleyes:

When I picked it up it was just showing Cam pos sensor G40 open or short, and that came straight back after clearing everything. By the time I got home we also had:

Fuel Trim bank 1 too rich
Multiple cylinder misfire
Cylinder 5 misfire
Cylinder 8 misfire
Cylinder 7 misfire

G40 is the one on bank 1 afaik - that makes sense, as does the fuel trim. The misfires on bank 2 seem a little odd, but then the cam belt was flapping about all over the place so who knows what bank 2 was doing. Interestingly the misfires only happened on light throttle. Give it a bootfull and it was fine - scary now to think that it could have skipped one or many teeth at any moment :eek2:

Here's an interesting shot of the tensioner. Pretty sure there should be a filter in the oil feed hole but it's nowhere to be seen. Given that the klutz who did the cam cover gaskets glooped the hell out of everything with some sort of evil silicone it wouldn't surprise me if the tensioner is blocked with some of it.

http://www.corradov8.com/pics/tensioner1.jpg

Here's another pic of how high it was riding when the cam jumps about:

http://www.corradov8.com/pics/tensioner2.jpg

The other one doesn't allow the chain to go higher than the two ears whereas this one just flaps about. I'm going to clean all the goop out of the engine so I'll have a look at the other one to see if that still has it's filter. At least I can nick the one from the ebay special if it's missing! The bottom shoe is locked solid btw - no idea if thats normal or not. I've dealt with engines which have these before, but never had cause to remove one til now.