My '85 Euro has S4 tensioner and tensioner arm.

So ... Do I need an S4 water pump or a pre-S4 pump??

What are the total sum of differences between the two?

 

Wasn't that part of the problem with your T-belt system... the tensioner was wrong?

They may have put the US tensioner (928 105 036 00) in place of the correct EuroS tensioner (928 105 046 06).

Do you have PET?

 

Show pics - and all will be clear ....
The S4 pump has a pivot stud on which the carrier arm pivots (17mm hex adjacent to the pump body). The pre-S4 pump has a cast, machined 'boss' that accepts the inner race of the idler bearing, and a pivot bolt for the carrier (17mm hex head containing the carrier arm).
Somewhere in the '85 - '86.5, the centerline of the tensioner body moved outwards 8mm, with a corresponding offset in the push rod 'dimple' in the carrier arm - all to better center the applied tension force to the belt center.
Need pics to decipher which combo ( mess) you inherited .... unless the above does it.

 

Wasn't change for the centerline done at begining of '86 model year?

 

The tensioner was the new one, and the arm the old one. I assume the pump is the old style since it's got the hex bolt and not the S4 stud and allen screw.

The way it was, was misaligned.

So, I replaced the arm with a matching S4 one, which I know will fit onto the pump and also will fit and line up with the tensioner. I am confident that what I need is an older style pump to take the existing hex pivot bolt.

 

Just be carefull H. There are three versions, early, middle, and late, and some changes in between those. The stud was even a different diameter, with the early arms being ever so slight different in that area too. I just made a mistake in the same area on the 78 build.

 

Thanks gentlemen ... OK I will do this:

1.) New S4 tensioner exists, no need to replace that at major expense.
2.) Use just-bought S4 arm to mate up with S4 tensioner.
3.) Take a look at the completely-dead, seized pump (btw it is a German rough-cast LASO). I will instal the arm and bolt and everything to ensure it all fits. And lines up.
4.) Order appropriate parts
5.) Instal parts
6.) Fluids etc check. then ... Check if car fires up (maybe compression check first but I'm sure I'll be too excited to see if it works)

Sound good?