Audi A4 B5 1.8 1998 petrol Camchain Rattle on start-up

[500comet]

Hi
A long time has passed since this subject was first raised but I have some history with this problem.
The camchain on my 170,000 mile 1998 A4 B5 1.8 became very noisy, so my very friendly Audi Mechanic had a look and found that the plastic tensioner pressure pads had broken up leaving the chain running on the metal.
A new one was around £230 from German and Swedish who do pattern parts (or sometimes Audi ones). This was too expensive for me so he fitted another one from a scrapped car for£100 and this was fine for 5,000 miles and then became noisy again.
He fitted another OEM one from a scrap engine which lasted 6 months, but had in stock a new Audi one which he had bought years before with a job lot of spares. This did not have the VVT electrical drive but looked as if it would fit - so I told him I would take the gamble and to fit it for around £100 for the whole job including parts.
The car runs very well with no noticeable loss of performance and the fuel consumption is better by around 10% which was a surprise.
The only remaining doubt after 8,000 miles is a short 1 or 2 seconds rattle in the morning sometimes as the oil pressurises the tensioner, but otherwise the motor is mechanically very quiet when running.
A new camchain, which takes longer to fit than the tensioner assembly, might cure the rattle but for the time being I will live with the rattle unless it becomes much worse.
I am a retired professional Engineer and at one time could have easily done all the work myself but at 80 years am beginning to find it physically hard these days.
My Audi mechanic however is a one man band and for instance has just provided me with an MOT certificate for the car having changed both drive shaft gaiters, all 4 brake discs and pads, a front suspension ball joint, and replaced a front brake calliper with a second hand one - all for £350 - it does not seem to be worth getting my hands dirty !!!

I have read that there is a check valve in the casting for the oil filter which stops oil retuning from the top of the engine when the car is parked and that this can stick open so that the tappets and chain tensioner rattle before oil pressure builds up.
I cannot find any reference to this in my Haynes Manual so does any one know about this valve please - which I fear will be very difficult to examine. So perhaps I will see my mechanic sometime who may be able to help.
Matty

[19birel]

Judging by the lack of replies I take it that no one else has heard of this check valve either. However, my first thought would be that it's not this mysterious check valve, but the chain itself. If the original chain guides had perished and the chain was just rubbing on metal, the chain would have worn at a considerably faster rate and possibly stretched slightly which would cause the rattle. My hypothesis would be that the chain is the source of your current issue.

[RENOxDECEPTION]

http://www.audizine.com/forum/showth...leshooting-DIY

Here you are sir, I don't believe a rattle on cold start for a few seconds to be too unheard of.

There is no check valve that I know of, but oil pressure does have to build up when the car is cold started, and the oil pressure tensions the chain when it does finally build up.

I don't think I'd worry about it too much unless it starts making the noise when it's hot also.

Keep what 19birel said in mind in the fact that the cam chain might have worn also from the metal on metal contact, it really all depends on how early you and your mechanic caught that.