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My cousin recently bought an A4 b5 with a 2.8 30 valve AHA engine that was running poorly. It recently had a timing belt, rollers, waterpump service. After buying the car he revved it up and managed to bend the valves on the right side bank (passengers side).
Great.
Upon disassembly the pulleys lined up as they should.. The timing belt didn't appear to be off or to have jumped teeth.
Inspecting the left bank head:
The cams half-moon key mark on the left side bank lined up with the arrow when the cam chain pensioner was in the UP position. (as we rotated them the tensioner would pop up and down)
Inspecting the right bank head: (bent valves)
Cams lined up in the DOWN position (nearly). In the up position the marks were off by about 1.5 - 2 teeth.
We suspect that something was either installed incorrectly (tensioner pads appeared fairly new to me) or perhaps the tensioner/solenoid itself failed and the chain jumped (no visible damage to the sprockets/gears). I didn't count the links (as I learned the number after researching before this post), so I cannot confirm if the chain stretched.
We are both unfamiliar with Audi engines (and the community).
What do you think the failure could have been caused by? I'd hate to see him pay to have these heads rebuilt just to have it fail again.
Disclosure: I have no experience with Audi engines or the terms I need to search for.
I would scan for codes, should have thrown a cam fault code. P1338 To tell you the cam timing was out. Or it could just be full of clutter by now.
The (poss) cause!
The cam chain tensioners, do not have full movement, causing the jerky action on the cam chain. Low oil pressure, blocked clogged oil ways.
If some one has been in there before, and been heavy handed on the Silicon sealant, they may have clogged up the oil passage filter under the cam chain tensioner, and blocked up the oil ways to the hydraulic piston.
Check the hydraulic timing belt tensioner, is not leaking oil and allowing the timing belt to become too loose under load, when revving the engine.
How many miles on the car?
The timing chain is 16 roller links, between marks on the cam and do not look to line up as well as the picture shown in your post. Is that for the 1.8T?
Unlikely the chain stretched, more likely the cam chain tensioner was not doing it's job, hence the poor running before.
03-21-2015, 05:40 PM
2.8 AHA bent valves with correct timing?
