murray928

Has anyone ever successfully fitted the timing belt tensioner assembly (P/N 928 105 066 00) designed for M28.43/44/45/46 type engines to an M.28.21/22 type engine. Porsche say that this part supercedes the one (P/N 928 105 086 02) used on the M28.21/22 type. If so, what other modifications were necessary ? For example, would you need to change the carrier for the tension roller from P/N 928 105 540 05 ( for M28.11/12/19/22 types) to P/N 928 105 489 00 ( for M28.43/44/45/46) ? Are these tension roller carriers so different that the later type is needed in order for the push rod on the tensioner to meet the carrier in exactly the right spot ? (the housing on the later (43/44/45/46) tensioner is wider than the earlier( M28.22) and therefore sits about 5mm further out from the engine face).

Any help would be gratefully appreciated !!!

Below is a link is to a really useful table from 928GT.com, listing the different engine types. Mine is a Euro S2 1985 model of M28.22 type.

https://www.928gt.com/t-928engine.aspx

murray928

A user (Aluminum) on another forum (Pelican parts) posted the following similar problem but whether it was resolved successsfully wasn'nt made clear.)

So I finally got my parts in the mail and discovered the tensioners are quite different.
The Early VS the Late type with the bleed screws . The Body of the late type is Larger and thicker. It sits out from the block more about 100 Thousands of an inch or so .The Push rod is of a different size then the early type and as the late type sits out from the block more and the push rod does not line with early type of "Carrier for the Tension Roller "
This is what pushes roller then the belt tight
Now the late type does bolt on to the early lock and it hits the dipstick tube just a bit . I expect you can just tap the tube a bit and it well clear ok.Or you could use a late type dipstick tube.
I also Expect to use the Late Type you need the late type push rod
and the late type Carrier for the Tension Roller and perhaps the late type Roller also .
Perhaps someone knows about such issues ?.

ttp://forums.pelicanparts.com/porsche-928-technical-forum/605480-bleed-cam-tensioner-1980-928-a.html

joejoe

Murray, I have a friend who sent his car in for t/b,w/p, rollers. A few month later I got to fix their work (this was a porsche shop they were not very good). What I found was they did not change w/p or rollers. They did sell him a new tensioner ordered from Germany! Unfortunately they installed the wrong one. (They ordered 3 different ones)

What I found : new tensioner used with original tensioner roller arm. These were not correct and caused belt to run on back of bearing and cut belt/waterpump face. Tom at 928intl helped figure out what was needed to make The new one work correctly.

His car is a us '84 auto, I do not remember what the part numbers used were, but Tom can help resolve.

ROG100

Basically you will need the complete assembly -
Tensioner, Tensioner arm, roller, idler roller, tensioner arm bush's and water pump for an 87+ car. And even then I am not sure that all would line up correctly with the cam gears. You are trying to use a system from a 32v engine on a 16v.

This is a VERY expensive and unnecessary way of moving forward. Just buy a good used tensioner from a reliable source in the UK and move forward without all the extra hassle and cost. It actually gains you nothing. Even easier would be to use a PKensioner.

There should be plenty of used tensioners available - talk to John or Simon or post on the UK board. You need a tensioner from any 84 to 86 M28/21/22 engine.

joejoe

Rog is correct. I should have said I tried to get my friend to just get used correct piece, however he did not get old tensioner back and wanted to use the new part. I should have looked where you are located. It was expensive to complete.

murray928

I took Roger's advice and ordered a second-hand tensioner. I got it from ebay Germany and it has the same part number as the old very corroded one stripped from my car. However the internal parts are almost 4mm taller than the ones taken out of my old tensioner. Can anyone tell me what should be the correct height of this assembly as it is possible that someone has made changes to one of these assemblies using parts from a later bleed type tensioner. I attach pics showing the part number and also the differing heights of the two assemblies.

Leon Speed

The taller one is no stacked correctly. It should be 4 washers one way, then the other way, like the shorter stack. Still, it looks like the pin is also longer. Is it? How do the old and new tensioner housing compare?

murray928

The piston is a different height. Almost 4mm longer . The housings are identical. Someone has made changes to one of the internal assemblies. Trouble is I dont know which one is correct. Both assemblies have the same number of bi-metal discs (35). I know they are not stacked correctly. I just put them on for comparison purposes. Thanks for taking time to help out.

Leon Speed

I'd be inclined to say the shorter one is correct because it appears from your earlier posts that is the original one. You could try to fit the rubber bellows and metal pin. It should sit naturally without stretching. If the taller one stretches the bellows you know it's not right.

murray928

Yes, the shorter one is from the original on my car. I will tell my mechanic to follow your advice and see what results. I'll post again on Monday to let you know. Thanks a lot for the advice. Dont know where I'd be without you guys on this forum.

Mrmerlin

FWIW you should have a look at the WSM it has detailed stacking instructions for both styles of tensioner washers, the stack on the lower side isnt correct

murray928

Thanks. I have found this on the 928 tech tips site. I assume they should be stacked as in the diagram, 7 groups of five ?

Chalkboss

Yes

Mrmerlin

Also note that there should be stacks of 5 washers in every stack,
so the 2 stacks with 4 are missing 1 washer each or 2 washers total.

GregBBRD

There's two distinct different length shafts, that correspond with two different lengths of adjusting bolts. I believe the change was in 1980 or 1981. The "early bolt" is hollow to allow the longer shaft to enter into the end of the bolt....that's how they kept the shaft centered. The later shaft fits into an internal round piece the size of the bore, with an o-ring on the outside of it. That is what keeps the later version centered. The adjusting bolt is shorter and not hollow.

I'd guess that you've got some "mixed" pieces.