Dutch 928 fan

I am doing a TB/WP refresh and am now fitting the tensioner roller.
This is what I encountered:

Problem nr.1:
-the arm pivot bolt had no bushings. The PO used electrical insulation tape by means of the plastic bushings...
-the new plastic bushings do not fit. I cannot push them flush to the arm surface. They go to deep and hit eachother, preventing me from pushing them all the way in.
-the pivot bolt has a smaller diameter than the bushings. I can move it around a lot, which would cause the arm to tilt when fitted... (It was indeed tilting when I took it off, but at that moment I thougt that was because of the missing plastic bushing...)
-arm part number is 928.105.540.03 and then followed by what seems to be a B or an R.

Problem nr.2:
-the tensioner roller (the big roller on the assembly) touches the arm when I install it without an additional washer between the arm and the roller. The circlip is installed correctly.

Problem nr.3:
- the old idle roller (the small roller on the assembly) is different from the newly ordered one. I bought all parts of on of the US reputed main vendors.

Are the parts mixed up? Were there different pivot bolt thicknesses?
Your wisdom is appreciated in solving this mystery.

Pictures will follow in posts below.

Dutch 928 fan

Bushings stick out. I could cut them shorter, but that just does not seem right.

Dutch 928 fan

Tensioner roller with the washer in between the arm and roller to clear it from the arm.

Dutch 928 fan

Different rollers. Left is new, right is what was on the car.

GlenL

Uhhh.... I'll do what I can.

I can tell you that you've got mis-matched parts. The shoulder bolts, arms and rollers all changed at different times. I recently found this on one of my cars: the arm was too big for the bolt. The bolt diameter was increased in '82 (I think) so you may have an old bolt in the mix. The arm part number is correct for your car.

Something to look out for is differences in parts with engine models. The same years have different parts. Do you have a PET listing? That gives parts by engine model.

Dutch 928 fan

Porsche 83-86 PET lists this:

Dutch 928 fan

And this.

GlenL

I gonna take a stab at it here...

You've got an early, like '80, shoulder bolt, an '83 arm and '84 rollers.

And maybe the nylon bushing you've got aren't right. Don't cut them back as the crown part helps the arm move and be secured. The shoulder bolt bottoms before the arm is clamped firmly.

Porsche, at the time, didn't cut over part versions between years cleanly. They worked through the inventory they had and then switched. Check the vehicle identification number groupings in the "Description" field.

I'd look very carefully at the PET for engine model and VIN groups that match your car, see what you have and then get new parts as needed. First off, the shoulder bolt is wrong for the arm. The early shoulder bolts are skinnier.

Wrapped with tape? You do never know what you'll find opening up these old cars.

Dutch 928 fan

Thanks. Yes, PO used tape as a bushing...
And the PO put the large roller bolt in reversed. So the end stuck out too far on the wrong side. So he decided to have a go at it with the angle grinder... Instead of just reversing it...

I think I will just order several different pivot bolts and bushings. Given that it is the right arm, I can then mix and match.

ammonman

From the engine type code (should be M28.11 for 1984 Euro S IIRC) and engine serial number you can determine the correct parts from PET and just order what you need.

Mike

Dutch 928 fan

Engine code M28.21 euro S2 twin distributor.
Vin WPOZZZ92ZIS811270

In the PET above I only see one type for part number 11, the pivot bolt.
I will scan some other PET...

Dutch 928 fan

Pre 82 has a different bolt... But as I do not know which one I have I will order both and see. I hate to halt progress for parts.... I wanted to run it again this weekend, but It will have to wait...ah well, it has been standing for a couple of months anyway.

worf928

As above, mis-matched parts. Pivot bolt (shoulder bolt) does not look correct. Washer pictured on pivot bolt has no place in this assembly. There IS a washer (see PET #12) between the bolt and the water pump, but it spaces the bolt; the 'shoulder' part of the bolt does not go through the washer. And it is an extra-thick washer. If you do not have this extra-thick washer, then order it too.

Idler roller: the 'new' part shown should work. It should fit on the boss on the water pump with the 'shallow' part of the roller towards the pump and the 'deep' part towards the radiator.

Bushings: I'm not sure - like others - that they are correct. However, since you did not include a picture of them 'out' of the roller carrier it is hard to tell. On the subject of why they will not seat, either they are too deep (and therefore the wrong parts) or you have some of the old bushing still inside the bore of the roller carrier. Take out the bushings and inspect the bore. It should be the same diameter all the way through. If you see a 'step' then you probably have some old bushing left in there.

Parts: It is important that the tensioner housing be matched to the roller carrier arm. The tensioner's pin (part 59 in your PET diagram) should line-up exactly with the ball cup in the carrier arm when the carrier arm is bolted to the water pump with the proper extra-thick washer (with washer between the water pump boss and the shoulder of the pivot bolt.) If it does not line up then either the tensioner and carrier arm are mis-matched or the pivot bolt is bent.

I would suggest, when you get the new parts, test fitting them with no idler roller or belt to make sure everything lines up. Once you have all the correct parts and are ready to do the final install:

- be careful turning-in the pivot bolt. It is very easy for the shoulder of the pivot bolt to catch the rear bushing and take a chunk out of it.
- when doing the above, be careful to keep the roller carrier as far 'clockwise' as possible. The nut and/or the rear of the carrier arm can bind on the water pump casting if you turn the arm 'counter-clockwise' as you turn-in the pivot bolt. If the arm binds on the pump you will bend the pivot bolt.

Dutch 928 fan

Dave, that is excellent information on the installation, very useful. I read it in your replies on the other thread where someone actually bent the pivot bolt. Thanks.
In reply to the above:
I do have the thick washer for the pivot bolt, so that is ok. I will remove the other.
Bushings are definately too deep. The bore is clean.
I will make sure I align the tensioner with the hole in the arm. The PO did this by adding a home made plastic washer... But when I get the right parts, that is something to delete...
Haha.

Garth S

You will find some of the (illustrated) data that you need in my 9 yr old post on tensioner trivia, as I have modified a few of these - and struggled to follow the parts upgrading from early models ..

Also, I had some more detail on shoulder bolt updates in this thread .... that was just prior to the introduction of a shoulder stud in the S4 cars ....

I have other references, but not to bore you .... bottom line, the bore of your arm looks to be 15mm, and the shoulder bolt you require MUST have a 12mm diameter with M8 threads .... the bolt you show is the very early 10mm dia ---- toss it!!

The 12mm id bushings are correct; however, if they meet in the middle to prevent the flanged faces from contacting the flats on the tensioner arm, you can either file some off the inner ends to allow a flush fit - or buy the 'older' 12mm version.