Greetings, everyone. I am new to this Forum. A week ago, upon start up, my A8 4.2L (with 104K miles) had flashing CEL and rough idling. Immediately shut off the engine. Got a VAG scanner and had several DTCs (P1340, P0300, P0301, P0302, P0303, P0304, P0306, P0321, P0133, P1602). I removed the valve cover on both banks. Cranked to TDC and verified cam timing marks as well as condition of TB, cam chains, plastic pad and cam tensioner/adjuster. TB looks okay and snug; cam chains look OK, tensioner pads look intact, with minimal scouring mark. I pressed the passenger side tensioner and felt resistance and springs back up; the driver side tensioner had little resistance and did not spring back up on release. As for the cam timing alignment at TDC, the driver side cam marks line up both for exhaust and intake; on the passenger side, the cam marks for the exhaust line up, but the intake marks are off by a roller pin. Does this mean that passenger side cam jumped time? If so, what could have caused it to jump? Not sure if driver side tensioner is bad. What makes the tensioner maintain the correct tension. Would appreciate any help.

 

The timing chain tensioners use springs & oil pressure to maintain tension. The fact that one is easier than the other to press down could be just a matter of the cams position holding more force on the chain.
Also did you check the cam timing with the Crankshaft locking pin & the camshaft holder bar?

 

Thx, M5S5 for your quick reply. I will get those tools to help check the cam timing. Cqn anyone pls explain or direct me to a thread how to re-time the cam? With regards to the cam tensioner, with the engine off and no oil pressure and no chain pressure, can you lift and push the tensioner piston by hand? How can you tell if the tensioner has gone bad? These tensioners cost some money and would feel bad to buy if mine is still operable. Appreciate much your inputs. Thx.

 

If you are checking any cam timing on the engine the base point would need to referenced with those tools installed. Otherwise every thing is just a guess.

 

pls pardon my ignorance, but where to insert the crankshaft locking pin? Bentley states "left" side of engine block. Does it mean driver's side? I have difficulty matching the illustration and the layout of the engine. Can anyone, pls describe the general location (e.g. what part is it close to). Thanks in advance.

 

I got the location where to install the crankshaft pin from another forum.
I hope this will help someone in the future.
Here's the link: http://forums.audiworld.com/showthread.php?t=2795790

 

Depending on the vehicle , it is usually around the left side engine mount covered by either a black plastic plug or the crankshaft position sensor on the side of the block. The pin actually fits inside of the crankshaft & locks it in place.

 

The person who posted the vid did a good job showing the location of locking pin:
Audi 4.2 40v timing belt prep - YouTube

 

Thanks, guys, for your very helpful posts. I am still waiting for the timing tools to arrive. Looking forward, can anyone pls tell me how to roll back/align the Bank 1 intake cam (the cam marks are off by a roller pin). Also, does anyone have any idea what would cause intake cam marks to misalign? The tensioner pads looked solid and the chain looked tight and snug. What signs would show if the cam tensioner is bad? I read other threads discuss about cam tensioner locking pin becoming stuck, thereby making the tensioner malfunction. For those of you who have changed cam tensioners, how does a "shot" cam tensioner look? Thanks in advance.

 

I removed the Bank 1 cam tensioner and to my surprise the lower plastic guide is gone and the chain has eaten through the lower tensioner piston. I drained the oil and removed the oil pan, expecting to find the remnants of the plastic guide. However, I just found some plastic bits. Has anyone any idea where the broken pieces will go? I am worried that it might end up clogging some conduits or oil ducts? Where should I look for the missing plastic pieces? Thanks for your inputs.