Hey guys
Ive had this problem twice now.
For some reason the engine keeps bending a valve on cylinder 2.
I had this problem occur before and we took the head off and replaced it.
Timing was done by camshaft markings and using the camshaft lock bar.
We recently finished replacing the valve and made sure everything was in place.
We hand cranked the engine with timing all set and each revolution was clear of any dings. Started the car last night and it ran perfect. Test drove it today and it drove perfect...until we drove uphill on the way home I heard a ding, pulled into the driveway and the dinging would sound and stop continuously. Also to add the lifters were all replaced with new ones. After the dings it started to run shaky and started sounding like a misfire. We did a compression test and the car bent the new valve on cylinder #2 again!!
Any suggestions?

 

Since you talk about the cam locking tool, can I assume this is a V6? You also talk about cam timing marks. Maybe you meant crank timing marks, cause there are no marks on the cams, at least no marks put there by Mr. Audi. I don't mean to picking at your words, but there are a fair number who rely on someone else's marks on that motor. The only mark to trust on the V6 is the one on the crank pulley. The rest is all timed with the locking tool.

 

Have the cams ever been replaced?

 

Have you pulled the head yet? I would guess that the bent valve is an intake valve. The timing belt only drives the exhaust cams. There is a chain from the exhaust cam to intake cam. When the head was assembled, the intake cam may be off by one or more teeth.

 

Yeah it's a 30 v v6.
Well on both intake and exhaust cams for both heads there is a notch on the shaft
and an arrow on the bracket according to my car. I'll have pictures up possibly by tonight.
So we did the timing by matching the notches, which when we checked the sprocket
washers it was lined up, Strange, then we put on the cam locking bar and adjusted the
crank putting cylinder #3 TDC and put the belt on from there. No the cams havent been replaced but the tensioners, chains, and pads.
Yes the head is already pulled, and yeah its the second time it bends the intake valve.
It was just replaced about 4 days ago. I've been doing some reading about the chain
linkage between the 2 cam shafts, and I read that bank 1 or passenger side but be
16 link rollers apart and bank 2 drivers must be 14.5-15 rollers apart. There's so much
being posted about timing a v6. I went by that and again everything matched up nicely
in the end. I read that the timing belt stretches over time and causes it to skip a tooth
because remember the car ran fine when we started it up, and on the 3 minute drive
home it bent the valve again.
Everything is taken apart and I'll have pictures up soon.
Thanks for your responses guys, I really hope to get a good solution. I miss driving my
Audi.

 

I apologize for writing so much, I'm just trying to be as informative as possible so we
can make this a long term fix not a 2 day in my case.

 

I'm just spit-balling here, but what about valve seat, piston (shape) abnormality, spring, rocker, sticking valve?

 

We did notice that the seat for the intake valve was slightly abnormal which shows that
whether we had a new valve in, it was always going to be leaking. We bought a fine stone
valve seat sander and sanded down the seat. We did a leak test with gas and nothing
seeped through after that. So thats one issue out of the way, but is still doesn't justify
if the re-occurring problem with valve bending will still be present. It's gotta be
something with the timing. I did notice that when we time bank 1 (turning the camshaft clockwise facing the front of the car) the tensioner goes up and with a slight delay
begins to move the intake cam. But it you move it counter clockwise (from same prospective) the tensioner goes down and the intake cam moves with a delay so when the intake cam is lined with the arrow on the bracket the exhaust is past the point of
timed. Until you move it clockwise again they match up and the tensioner is up.

 

Something's loose somewhere (unless the cam lobe is abnormal).

 

Well we just found out that the oil pressure light was flashing while we tested the car.
Were assuming that the oil pump isn't distributing enough oil to feed high pressure to
the chain tensioner and the lifters.