danglerb

Any comments from the PO or the shop they used?

I don't see how they could have missed the poor tracking of the belt.

ROG100

I will leave the naming of the shop who did (didn't) do the work to the owner of the car.

ROG100

Bill,
Heres a pic of the left hand cam gear with the TB in place.
Slightly off center but no where near the front as on the right side.

JKelly

If the tensioner wasn't dry, or had more than a couple of drops of oil in it, then the only thing that could be causing it would be worn tensioner arm bushings.

heinrich

John, what about a worn crank gear and wear on other components?

JKelly

Hold on, let me get some photos together to compare with Roger's.

danglerb

Back of the belt sure looks like its been abused.

928drvr86.5

Hey, is that silver grade anti-sieze compound on the back of that belt?

ROG100

Ben,
No its the camera light.
H,
Most everything else is good. The wear in the tensioner bushings is the worst. The pivot bolt seems to be staright but worse for wear.

I still can't get my head around why the belt was not central on both rollers. The wear indicates it had been like that for a long time.

Lot of wear on the smooth side of the belt and shown by a lot of wear on the idler roller.
Idler rollers I have seen do not normally show much wear???

928drvr86.5

I was just kidding

JKelly

I would think that the other gears would wear long before the crank gear.

These photos are from my car (86 with 78k). Look familiar? The timing belt had been changed 6 or 7 years ago. I don't know how long it had been riding forward.

The belt on the passenger side cam gear (shown) was more forward than on the driver side. Both gears are in excellent condition and show no worn spots or dishing.


The belt had just started grazing the tensioner arm.


The belt was riding off of the tensioner roller.


The tracking marks on the old roller (new roller on left). The roller didn't appear to be worn. There was no side-to-side movement and the roller rolled freely without any binding.


The shaft bolt was not bent (YET). The washer is the correct one and in the correct place.


The bushings were not cracked. You can see where the belt was rubbing on the tensioner arm. Also, you can see that the lower face of the bushing is a little shiny. I believe this is caused from the belt pulling on the tensioner arm when it rubs, which causes the arm to flex downward on the bolt, which would have eventually bent it. The shiny area on the bushing is then caused by pressure in that area from the thick washer (see previous photo). Increased pressure from the belt on the tensioner arm could probably cause the bushings to crack.


The other bushing.



Here is what Roger has said so far:
The belt was more forward on the passenger side than on the drivers side.
The tension was fine.
The pivot bolt appears straight.
The cam gears are fine.
No play in the tensioner roller.
There is some slight wear in the two non metallic bearing inserts where the pivot bolt passes through.
Tensioner needs TLC, but has oil in it.
The lettering on the back of the belt was worn (normal?).

Here is what I found with mine:
The belt was more forward on the passenger side than on the drivers side.
The tension did not seem too tight; although I didn't have a kempf tool at the time.
The pivot bolt is straight.
The cam gears are excellent.
The oil pump gear is excellent.
The crank gear is excellent.
No play in the tensioner roller.
I don't remember any looseness in the shaft bolt, but the two tensioner arm bushings appear slightly worn. The wear is even on both bushings, which may or may not keep the tensioner roller in a perfect vertical plane. The shaft bolt is shiny where the bushings rub, but it is not worn uneven. It is not dull looking like Roger's.
The rubber boot on the tensioner was cracked and the main housing where the belleville washers reside had two drops of oil left in. The chambers on the back of the tensioner had a thimble full in them.
The lower idler roller was binding, but still rolled.
The lettering on back of the belt was gone (normal?).


I did the full t-belt procedure with rebuilt tensioner. I didn't change the any of the gears. I changed the water pump and changed the lower idler bearing. I've put 500 miles on a new t-belt and the belt hasn't moved off center at all; at least not yet. I think the problem is either in the tensioner or in the bushings. If Roger didn't find anything wrong with his tensioner, then it is probably the bushings; unless his lower idler roller was binding too, then I guess there is a chance that could cause the belt to wander on the tensioner roller.

Edit: I was originally thinking that somehow the tensioner wasn't dampening the vibrations properly, because it was dry, and letting the belt become slack on the tensioner roller for short moments. But now it kind of looks like the bushings cause this.

ROG100

John,
Thanks for taking the time to post and I think we have a "match".
Seems to be the same issues.
I will change everything out and see.

New Question - what about using a post 87 WP and using the added bracket from the pivot point to the WP. Will the tensioner roller assembly with a later idler roller fit or do I need to change something else???
This mod would stop this happening again.

John,
I am using your 928 manual side by side with the Pirtles writeup. Noting differences and comments.
I will let you have a copy after this is done.

marton

This was the set up on my 82S, New type WP, new idler roller, old tensioner assembly and old roller.

Marton

worf928

Jim Baily responded to this question not too long ago. IIRC, the center timing belt cover is different along with the WP pivot. There was a longish list of parts needed for the 'upgrade.'

I'll see if I can find his post.

EDIT: Cannot find it. Jim will need to dredge...

ROG100

Dave,
The bushings for the tensioner arm are the same.
The center TB cover is different but can be changed to accept the extra bracket very easily.
The 87 WP does not come with the pivot pin so I will need that plus the bracket.
Also the screw and a couple of special washers.
Any other gotchas?
Is the tensioner carrier the same?
87 is 928 105 489 02 the one we have here is 928 105 489 0R (yes R )