Allroad tdi - tapping engine noise

[Budge1]

My car has just developed a tapping sound which sounds like camshaft. Don't notice it on start up, only very noticeable with the window down when going slow, say driving in town. Not noticeable when ticking over hot. Car accelerates well, is not using oil and good on fuel. Have looked on the forum - seems to be pointing towards camshaft but could it be injector/vacuum pump/cambelt tensioner/cataltic converter?

Any suggestions would be appreciated.
cheers
Martin

[Crasher]

Does it rattle at idle when hot but clear if you bring the revs up a bit and then com back after a few seconds at idle? What year and engine code is it?

[Budge1]

Just been driving this morning. The 'ticking' is quiet from cold, drove 4 mile into town, quiet at speed very noticable when coming off the gas, very reminiscent of a camshaft rattle then it disappears. Pulled up in town and all is quiet. Drive away and after a minute or two it comes back. Seems to be intermittent. Engine is generally quite when this tapping is not there and there is no power loss.
At tickover ( and at normal temperature) it is difficult to hear, can hear it a bit when you rev it and engine returns to idle but then it will disappear altogether.
cheers

[Crasher]

What year and engine code is it?

It sounds like one of the oil retention valves has failed.

[Budge1]

Hi Crasher
car is late 2003, don't know about code, but believe it is the 180bhp model with manual box.
Thanks for the tips, need to get it into a garage, oil change is due anyway. Are the oil retention valves expensive?
cheers
Martin

[Crasher]

The valves are cheap but a complete **** to get at, hours of work.

[Budge1]

Hi
Just had my car in - engine flush and oil change (due anyway). Noise still there and told it is a suspected tappet, advised to monitor it for now - nothing else suspect. Mentioned about the retention valves and he wasn't fully aware. He was aware of a pressure relief valve? Any insight would be appreciated
Cheers
Martin

[Crasher]

The retention valves keep oil in the heads at low pressure, they are in the middle of the V.

[Budge1]

Hi Crasher
Thanks for the advice last night. I did go and have a look at the camshaft through the oil filler cap as you suggested, difficult to be sure but looks like there is a bit of wear - slight scuffed and discoloured lobe, need to get the cover off to have a good look.
Even if there is slight wear could this be due to oil starvation as a result of these non-return valves. It is said that long life services reduces the life of the camshaft only. Why is this? Does the oil become sludged up causing blockages, surely there would be wear elsewhere in the engine - mine has had 15000 miles intervals, uses 250ml between oil changes and returns 32mpg (manual).
Basically is there not enough emphasis placed on these non-return valves ( don't think Audi dealers are clued up on this in Cork anyway!) because if the oil is breaking down and performing out of specification then wouldn't there be other issues elsewhere with these engines -) Looking back my problems may have started with the extreme cold weather we had car seemed quite noisy on initial sart up and short school runs - even the wife noticed it!

One thing I did forget to ask you is engine flushing recommended - spoke to another audi specilalist who said it may be worth flushing with 'forte' flush - drive steadily for 10-15 miles, ie under steady load, tick over then drop oil, refresh with new oil & filter.
Anyway if you could forward on the info regarding changing non return valves and any other related info to budgebailey1@hotmail.com it would be greatly appreciated. I may have to bring it across the water for repairs yet - probably cheaper!!

Cheers
Martin

[Crasher]

I tried to email you but the address kicked back, so thanks for the address, I will re-send it?

LL oil reduces the service life because the oil is not really capable of what is being asked for it an human nature being what it is, people push the intervals 2, 3K or more over and the oil just cannot take it. Use LL3 and change it every 10K and it is fine, leave it to 15 or even 20K and the most heavily loaded part of the engine will suffer and that is the cams.

I try and get people to have the oil retention valves done when I do cams but it adds almost a day to the job and the turbo also suffers from the oil breaking down so whilst it is off for the valves we suggest a rebuild. The trouble is in many cases this lot adds up to more than the car is worth.

If the engine is clean, flushing is a waste of time and in certain cases can cause deposits to break away and block the sump pick up.