what are the odds?

[oil4blood]

I recently Scooped up an 01 beetle tdi auto Trans with the alh motor. Bought it non running been sitting almost a year. Guy said his daughter was driving it and it just quit. Got it home and checked the timing belt it was not broken. Sticker said it had been done at 175k car now shows 199k. It was really loose tho. So I tore into it to find the tensioner missing the back tab. From all I can tell valves did not hit the pistons. I pulled the cam and to throughly inspected the cam, lifters (top and bottom) saw nothing more than ordinary wear. So what are the odds I avoided a more costly repair?5

 

[UhOh]

20,000 to 1

If you can get 20,000 miles w/o incident then you'll have likely escaped a costly repair.

Problem with something like this is that there is clearly a failure to install things correctly, which would leave one wondering what else might not have been done properly.

Without having the actual documentation supporting what exactly was replace (even IF), and by whom, you're really best off treating it like it needs to be done, all of it.

 

[oil4blood]

Oh yea it's getting a whole new timing belt kit. I just don't want to get it all put back together and find out pistons really did hit valves. Other than pulling the head I can't see any sign of it.

 

[oil4blood]

Could such a thing happen just right like that? Best I can imagine is tensioner let go and the pump got out of time enough to kill it.

 

[Bran Diezel]

Leak down test

With the belt off you can roll the crank back about 60 degrees then use a straight edge on the crank sprocket and make 4 marks on the cam all 90 degrees from each other and go by firing order and check each cylinder at tdc for leaks

 

[Bran Diezel]

Or just put your new belt on with everything lined up, put your harmonic balancer back on and start it and see what happens.

The belt won't roll off with the balancer on it

 

[UhOh]

You really have no idea what happened when the engine quit. Install belt and new components, turn over by hand to verify no obstructions (and that the locking tools insert as they should). If you're good here then you MAY be OK; I'd want to have some assurances that the engine didn't hydro-lock or such. Others, hopefully, will chime in, but perhaps one can pull the glowplugs (or injectors?) to see if anything is amiss. I'd want to do a compression test: http://forums.tdiclub.com/showthread.php?t=353237

 

[gforce1108]

The tab does nothing once the tensioner is torqued down. If all the timing marks lined up before you took it apart, I wouldn't worry about it (other than making sure it gets installed correctly this time, with new parts).

 

[oil4blood]

I did check the timing before I took it apart and everything lined up except the pump. And this was even after I turned the key.....

 

[swapmeat]

Are the pump sprocket bolts tight? Maybe only got torqued to 15ft lbs but NO extra 90 degree and while in use (especially an 11mm pump with extra timing belt pressure, thus lower service interval) the sprocket moved.

 

[oil4blood]

They were tight. I didn't check to see if they were properly torqued tho

 

[oil4blood]

The pump bolts were tight but I didn't check to see if they were torqued to spec

 

[jettawreck]

Typically when/if the tensioner fails (or "releases" as yours may have, although as mentioned, the nut should hold it if installed/torqued properly) the belt "slips" at the crank sprocket as that's the tightest turn and where the power to turn the belt system comes from. However, IF the cam/crank timing were still correct and the IP was out, you MAY have dodged the big one.
At that point it would be your judgement call whether or not to go deeper, or just replace the TB kit and see what happens(ed).
Too bad its the automatic tranny.

 

[swapmeat]

If you know a mechanic..we have a snapon boroscope at work that would go down an injector hole to look at tops of pistons

 

[mrbowtieguy]

You think those are high odds, I have picked up 2 TDIs this year where someone did a timing belt job and didn't bother to replace the tensioner. Both Tensioners bearings shelled out broke the tension spring letting the belt slip a couple of teeth on the IP til it was too far out of time to run. So it is possible. And I'd be willing to bet that if its a tensioner failure your more likey to come out unscathed as opposed to a TB failure which always means disaster.
Installed TB kits and both vehicles were up and running.
Just pick one up recently that has a flat Cam lobe and collapsed follower. only 50k on the last TB, The belt didn't break and it was still running.