dprantl

The factory tensioner is fine, but it is in no way superior. It is a fixed tensioner for a rubber belt that can stretch, requiring periodic checking and manual adjustments. That's the very reason there needs to be a low tension warning. With an automatically adjusting tensioner, there is no need for a low tension warning because the tensioner automatically adjusts to take up any slack if the rubber belt stretches. It has been said many times, modern cars with timing belts have automatically adjusting tensioners and no tension warnings. Why anyone would think that the 928 system designed in the 70's is superior is beyond me, especially with all the documented problems that have occurred with the stock tensioner. If Porsche wasn't running out of money in the early 90's, they would have updated the 928 tensioner to be automatically adjusting, just like the 968.

Dan
'91 928GT S/C 475hp/460lb.ft

rexpontius

AMEN

SeanR

Perfectly said, but you won't convince them. Same type of mindset as those that preach you can't put 18" or 19" tires on our cars with out putting other peoples lives in jeopardy.

rjr0928

Porkensioner +1

depami

That's a new one on me. What's the logic there?

SeanR

A few years ago some of the UK guys had a ****fit about it, now they pretty much stay quiet.

http://www.928.org.uk/index.php/124-hidden/60-wheels

69gaugeman

Reading for comprehension. I didn't say that the tensioner was superior. I said having the sensor is superior. If the tracking fails that tensioner will keep it tensioned all the way till it breaks.

Porsche stated 19 inch Tires are not to be used on the 928.

Imo000

What happens when the water pump freezes and the belt start streching and there is no warning system in place? I said in many times and will as long as I can that this saved my Canadian bacon once. The belt was seconds away from snapping. Look for my thread on this, it's about 4 or so years old. Wait until this happens to the Audi setup and bitchfest will start.

rexpontius

Why did the waterpump fail in the first place?

Imo000

Because it reached the end of its service life.

PorKen

BELT TEN. o<O ≠ SERVICE ENGINE SOON

rexpontius

Bearings tend to fail prematurely when faced with too much tension....
This is what I think is one of the major risks of the factory tensioner design.

If the low tension warning comes on, many (not 928 specialized) mechanics increase tension and all seems fine, however overtensioning does not immediately result in any problems (or warning lights )

Only after several hundreds (maybe thousands) of miles, all of a sudden the waterpump bearing fails.. or camshaft gears have big wear... anyway I think my point is clear.

This is why I dont like the factory design and I am a big fan of the porkensioner.

It might also be a bit of a personal obsession, having specialized in Alfa Romeo V6 timing belt services (think I have done > 60 belt changes...) and I have seen the development of early hydraulic tensioners, to mechanical tensioners, to porken/audi style tensioners.

Anyhow, I think the Porkensioner is one of the best updates for any 928, along with a constantine clamp or pklamp.

jcb928

or because it was not changed preemptively.

depami

Where can said documentation be obtained?

One could argue that a system requiring adjustment is a good thing. Each adjustment event is an opportunity for belt inspection.

Installation of an “automatic” tensioner could result in "automatically adjusting" until failure occurs.

Imo000

What's the point of that if the warning system is in place?