2003 Jetta TDI Potential Timing Belt Tensioner Problem

[RabbitGTI]

Helped a friend change his timing belt. The tensioner was the old B4 style with a tang that goes into a slot in the block at 10 oclock. The tensioner nut was tensioned to 15 lb/ft. Turned the tensioner clockwise to tension the belt. The tab was not centered in the notch on the tensioner, but the tab was in the notch, so it was close. He went for a 10 mile test drive and the now the tab on the tensioner seems to have moved and is outside the notch by a tiny bit. ***? I have done a couple dozen timing belts and have never seen this happen. Do we have a problem?

 

[Terrific-In-Tahoma]

Yes.

The problem is metal fatique creeping in to the steel that is the tang of the TB Tensioner.

As the engine goes through its accelleration /deceleration cycles, it pushes/pulls against that tang, and eventually will bend from fatigue.

IMHO replace it now,while you can, rather than later, when the valves are pushed into the pistons (ASK how I know)....

 

[RabbitGTI]

The tensioner is new.

 

[Louie710]

Replace it immediately unless you want your engine to look like this

 

[BobnOH]

I'm not sure wha we're talking about here Jasper.
The tang must stay in the hole to retain the thing. The index mark should be aligned fairly close after tensioning. It has been observed that the index may shift a bit. Just keep an eye on it for a few trips.

 

[Terrific-In-Tahoma]

The tensioner is new.

Even though it is "new", what you have described is the tang of the belt tension pulley going out of spec, and bending. (possible defective steel from the factory, getting past quality control.).

The steel used for the blank that the tension adjusting cam is mild steel, and is easily formed or stamped. This also means that the steel is very soft (relative term).

I had one of these sheer off, 3/4 before a violent upshift, the stress on the downshift caust the tang to bend , and the Timing Belt to skip one cog, and throw the "timing" off.

IMHO, for the cost of the part (unless it is made from cast titanium, and hardened steel), then I would replace it now, rather than later.

Your mileage might vary.

 

[BobnOH]

Even though it is "new", what you have described is the tang of the belt tension pulley going out of spec, and bending. (possible defective steel from the factory, getting past quality control.)...............................................

If this is what is happening, get a new one. Like I said I was confused.

 

[RabbitGTI]

Thanks all.