Timing Belt running off

[Dankemp]

hi guys just pulled the belt cover to move my IP timing, to find this :/....

seems half the belt has been rubbed away !!

any ideas of what can cause the belt to run off ?

 

[V-DubLuv]

A cheap rubber timing belt will do this, it happened to me also.

 

[PDJetta]

Proth, or many of his aliases, parts? Where did the timing belt come from? What brand was it? Likewise with the other related parts. Who installed them and how?

--Nate

 

[JB05]

Don't know the answer, but I'm guessing your location is South Wales.

 

[migbro]

Some element of the timing belt path is off axis. A bent tensioner stud is high on the list of possibilities.

 

[Dankemp]

gates timing belt, water pump is a cheaper plastic on but is aux belt, INA tensioners + idler with new stud+bolts, in march 2012.

i fitted the belt , as per many guides

 

[Dankemp]

forgot to add , belt has 8k miles on it :/

 

[oilhammer]

Not sure on that engine code (since it was not sold here) but some of the earlier EA827 series TDIs sold here had issues with the pump bracket alignment, and there is a TSB about it.

Basically, you take the pump off, loosen all the bracket bolts holding it to the block, push the bracket down in front (belt end) and up in back (flywheel end) and retighten the bolts.

See if someone in your area can look up TSBs for you. We had it for the 1Z engine in the B4 Passat 1996, but I have seen the issue on AHU engines in 1998 Jetta (Vento) as well.

Good luck!

 

[Herm TDI]

Check the intermeadiate shaft sprocket. If the wooddruf key (or the sprocket slot) is damaged the sprocket will wobble thus permitting the belt to ride against the lip of the tensioner.
If this happens the results is a "chewed" belt.

 

[Dankemp]

on the IP or Crank ?

thanks

 

[Windex]

On the Intermediate shaft - it's the smooth, large pulley below the Injection pump pulley.

Get a new belt, and replace per procedure - I think you'll find that Oilhammer is right on this one - the accessory bracket my need to be shimmed.

Once you get the new belt on, check the alignment of every pulley (preferebly with a straight edge) to verify alignment.

 

[Dankemp]

ah right i get you , found that on the cambelt diagram , it says to replace the shaft seals too , and o-ring

 

[Vince Waldon]

It's a long shot, and I'd sure eliminate other possibilities first, but worn intermediate shaft bearings can cause this as well... really common back in the IDI days, but a possibility on any engine design with an IM shaft...particularly if the engine has a manually-adjusted belt tensioner and someone over-tightened the belt. Not totally familiar with your particular engine so this may not apply.

They can be inspected if you're pulling the sprocket and bearing anyways....hopefully they don't look like this:

Like I say... not totally familiar with the A4 config of the TDI engine so this may be a wild goose chase... but if it has an IM shaft it has IM bearings that can wear and throw the timing belt path out of alignment.

 

[oilhammer]

His engine is the older type, same as the IDI diesels (and old VAG gassers, for that matter). I assume this is a 1998ish A4? I can at least tell that much from his picture. Old style steel bracket where the upper roller is attach, 3 nut down the center valve cover, little nut on the pump shaft. Basically, an AHU engine turned longways, with a slightly different turbo and injectors and making 110hp.

 

[Vince Waldon]

Thanks O.H.... manually-adjusted belt tensioner, per chance?!

 

[PDJetta]

The babbit metal on the intermediate shaft bearings would flake off on the 1.6 IDI diesels and you could get some pretty large clearances. I also believe it is a nightmare to replace them, such as the engine has to be removed from the car to do it and they must be sized to fit. Notr sure about your particular motor.

--Nate

 

[RIP TDI]

For 1Z/AHU (should be applicable to AFN): TSB Group 15, Number 97-01 describes the problem as "Toothed belt runs toward outside and wears out, jumps off, cracks or is noisy."

Synopsis of the TSB procedure: Make sure that the belt tensioner has been replaced. Then, remove the vibration dampener/pulley and start the engine. If "the belt protrudes beyond the face of the crankshaft sprocket", the condition can be remedied by removing the pump, loosening the 3 pump bracket-to-block bolts and rotating the bracket counterclockwise (viewed while facing the front of the car).

While not specifically stated in the TSB, if the belt is off track in the other direction (i.e., toward the block), the bracket is rotated clockwise. Elongating the bolt holes may be necessary if there isn't enough angle correction available.

 

[oilhammer]

Thanks, Chris. That was the TSB to which I was referring in my previous post.

 

[Dankemp]

thanks for that ,

surely if that was the case wouldn't the other belts that got the engine too 216k miles be the same ?

 

[RIP TDI]

What other belts drive the injection pump? Rotating the injection pump bracket affects only the timing belt.

 

[whitedog]

What other belts drive the injection pump? Rotating the injection pump bracket affects only the timing belt.

I think he means the previous timing belts.

 

[RIP TDI]

Oh, right! That does suggest that its not the pump alignment but rather something to do with the most recent TB change: tensioner, bent tensioner stud, idler bearing, etc.

 

[whitedog]

I agree. The only variable is if the mounting bolts came loose a bit. With the tension on the belt, I think that this would cause the bracket to rotate CCW as viewed standing by the left tire. (remember this is a north-south engine not an east-west engine)

Also, note that I know next to nothing about these engines and I'm just guessing on stuff, so now that I have said this, I can't be blamed if others tooef their engine.

 

[Dankemp]

Would the belt automaticaly go the the outer edge of the pulleys if somthing like the timing belt cover was rubbing on it ?..

e.g if there was nothing wrong with the belt nor the installation but the cover was installed incorrectly and rubbing the belt , would the belt just come the the edge as it was being worn away ?

 

[oilhammer]

You may be overthinking this. I really would google that TSB number Chris posted, or check with your local VW/Audi dealership for a printed copy. You know you already have to do the belt over again, the TSB procedure literally only takes an extra 30 minutes or so to carry out. I really think you'll find that will fix your problem. Every one I have had like that it did.

 

[RIP TDI]

I know the cause of bad belt tracking on ALHs is usually a bent tensioner stud. I'm not sure I've ever read of that being the cause on a 1Z/AHU; it always seems to be a FIP bracket alignment issue.

 

[whitedog]

Dan, let us know what you find and if possible take a few pictures, if you would. I'm interested to see this.

 

[Dankemp]

Dan, let us know what you find and if possible take a few pictures, if you would. I'm interested to see this.

haha, old thread but good info if someone found it on google.

INA tensioner stud was at fault , was bent slightly and not tight in block, but nut was tight on tensioner.

 

[CNGVW]

hi guys just pulled the belt cover to move my IP timing, to find this :/....

seems half the belt has been rubbed away !!

any ideas of what can cause the belt to run off ?

If you look closely you can see the adjuster is acting like a saw blade. Its all the way to the out side lip. I would think the roller bolts may be bent and possible the adjuster some how is cocked. A water pump that was machined wrong could do the same thing. One other thing is if the head was removed and the locating pins were removed and the head was placed with a small shift . The heads passenger side pushed to the firewall and the drivers side pushed to the front it will do this.
Bob Mann