[Biturbos4] I think I really did it this time (timing belt gonewrong) HELP!

Keman keman at interwolf.net
Mon Nov 15 15:37:48 EST 2004

Ohhh boy. Hehe. Oh boy. Where do I start.

If the engine idles fine the noise you're hearing isn't the pistons hitting
the valves. Once that happens it won't idle worth crap and you might as well
go out and get real drunk before getting the estimate bill. Both cylinder
heads to be removed, rebuilt, and/or replaced and reinstalled ... I see
$7000 easy ... why so much? Step one: remove engine. Step 2. Remove turbos.
Step 3. Remove cylinder heads. ... you get the idea.

So. Lets hope that didn't happen.

Ok. First off, the teeth on the timing belt are meaningless on the 2.8/2.7L
engine. Audi knows that belts vary slightly from maker to maker, so why let
the teeth limit the calibration? The cogs on the cam are infinitely
adjustable in relation to the camshafts actual position. Once you put the
new belt on, you SYNC them to be exactly where they need to be.

The cam lock tool (the big huge bar) actually /positions/ the camshafts in
relation to the cam cogs. The cogs are not keyed. They can sit on the
camshaft in any position, but the "washer" with two holes in it which you
keep parallel to the ground? Those /always/ are in sync with the cam
since -they- are notched. Yes, FRICTION holds the cam to the cam cog. No
kidding here. It's always been sufficient and noone I know has seen one slip
so it's a good design and don't worry about it.

First things first-- time to get the cams in sync.

1. Roughly line up the crank/cams so that the smaller holes on the cam
washers are facing towards each other (towards the center of the engine) and
the TDC mark on the crank pulley is at the notch in the cam belt cover.

2. Remove the crankshaft position sensor down on the front drivers side of
the block and insert the special audi crankshaft lock tool (purchaseable at
your audi dealer). As it threads into the hole the crank will get budged a
little and is now exactly where it needs to be and cannot move.

3. Take the belt off. I know, this isn't what you wanna do but you gotta.

4. Take off the bolts that hold the cam cogs on to the cams.

5. Now, using VAG tool xxxx (or your favorite hammer) give the cam cog
washer (that thing with the holes in it under the cam bolt) a few good
whacks. Act like you're trying to bend it towards the engine. One sharp one
should break it free and it will fall onto the ground into the bucket of
used oil you left there on accident from earleir. Don't worry about it now,
we'll fish it out later. Next put a rag over the cam cog and give it a good
whack on the forward facing edge. It too will fall off. If your driveway is
on a hill make sure to chase after it before it ends up on the street.
Repeat on the other cam.

6. Lay the cam cogs back onto the cams and the washer/bolts back on, and
tighten the bolts by hand down to the point where the cam cog can rotate
freely from the camshaft with only minor interferance. The cam is tapered.
The cog should be sitting on the cam rather loosely right now for this to
occur but tight enough that it can't rock much back and forth.

7. Take the special audi VAG camshaft sync bar tool (or your favorite
substitution) and slide it into the holes of the "washer" that's under each
cam bolt. THIS SYNCS THE CAMSHAFT-- it is critical that it locks into the
camshafts perfectly. It's laying across the engine essentially 'connecting'
the two camshafts to one another and resting parallel to the ground. You
will have to slightly turn one cam to get the bar to stick into all four
holes perfectly and in doing so the cams are now perfectly in sync, and the
crankshaft is still locked and exactly where you want it.

8. Put the belt back on with this bar still in place. Let the cam cogs
rotate as they need to during this process. Remember, they are capable of
turning, the cams cannot.

9. Release the tensioner. Give the belt a few tugs, the cogs will turn
slightly to let the tension complete.

*** A note about the hydraulic tensioner- compress it using a vice NO FASTER
than 5 minutes. That is you will sit there slowly turning the vice at
sufficient speed that it takes 5 minutes to fully compress the piston. Any
faster and it ruptures internally and you've toasted your timing belt
tensioner. Once it's fully compressed stick a hex key or drill bit through
the holes to get it to lock like you would put a pin into a grenade.

10. Torque the cam bolts down to spec. 45 ft/lbs if memory serves. Do not
use loc-tite.

11. Remove the cam position bar and the crankshaft lock tool. Put the CPS
back in and dress the engine all back up.

12. Poof. Yer done. Drink german beer- I suggest Gordon Beirsch Pilsner. :)

- Keman

> Yeah, I have to concur with Igor, Matt.  That noise is a pretty
> unmistakable clanking.  I wouldn't reccomend messing with it for another
> instant and take it straight to a paid mechanic.  If you're religious,
> Aaron LaPointe
> 01 Nogaro $4
> MattOVR6 at aol.com wrote:
> >So I got ambitious today and decided it was time to change the timing
belt on the 00 S4.  I got it all apart, and it went fairly smoothly.
> >
> >I didn't have the cam lock tool, but I fabricated a makeshift one out of
a 2" metal strap that I thought would do the job.  I had it slip off as I
was removing the belt, and the passenger side cam sprocket and cam popped
and went to the left.  I had marked it before on both, so I brought it back
to that point and reattached my camlock thing. When I started the job, I
rotated the crankshaft to the point where the holes in the cam sprocket
flange were parallel to the ground. As I was putting it all back together,
and checked my marks, and they were just a slight bit off, but both of them
were, so I assumed that it may have turned a bit.  But the toothed belt
would not let me change that at all.
> >
> >So I put it all back together, and it idles fine, and during slow rev
climbing is fine as well.  But if I stab the throttle, I'm getting an awful
clacking sound that sounds like it's coming from the middle of the engine
somewhere.  I can't tell whether it's due to timing being slightly off, or
what else it might be.
> >
> >I took it all back apart to make sure there weren't any tools in there or
things that I had missed, but it checked out fine.
> >
> >Is there a way that I can check the timing, or find the TDC mark and
index the cams?  I've heard that Audi cars do not have any sort of indexing
mark on them, but can't verify that.
> >
> >I need your help, Audi Gurus!
> >
> >Thank you,
> >Matt O.
> >2000 Audi S4 (74,000 miles)
> >1995 Turbo Jetta 3.0 VR6
> >
> >p.s. Spare the lecture about how I should have bought the $180 Audi

More information about the Biturbos4 mailing list