the timing belt which is about seven feet long wraps around all the gears , pulleys on the front of the motor . The only things which keep the belt lined up on the gears , they do not have any shoulders or lips , are the two cupped shaped washers on either side of the crankshaft drive gear . Note the lip curves away from the belt . If one or both is installed with the curve toward the belt they will eat into the sides of the belt , not a good thing . There will always be some observable movement back and forth on the camshaft gears as the belt never tracks 100 % true but the thrust washers on either side of the crank drive gear pushes the belt back into alignment .
Driving with out the plastic covers will cause accelerated wear of the aluminum camshaft gears and the risk of foreign objects getting caught by the belt -- the family cat - a shop towel - your finger - etc. So a long answer to a short question - normal movement

Jim Bailey
928 International


OK, I have finally gotten to the T-belt, removed it, and am trying to get the tensioner out.   I have removed all bolts, but the tensioner bracket is still connected to the air pump by some sort of pin.   At this point, should I remove the pump and tensioner together, or is there some trick to getting the tensioner out by itself.



87S4 Auto Black/Black

On my 83, the tensioner came off without messing with the air pump. I think it is just stuck.
They usually have a bunch of gasket  sealer betwixt the engine block and the tensioner to keep the heat-transferring oil from leaking out.   I think it will prolly come off with a little prying. But the 87 may be different from the 83 in this area, so YMMV!  There is an O-ring down inside the tensioner. You can get a replacement one at NAPA. Just take the old one in.  But you have to purchase a new cap for the top as your existing one is prolly hard and cracked.  I made a nice leather cap for the tensioner out of an old boot (still nice leather) but decided I wasn't in a hurry, so I got an official Porsche cap.  The leather one would have lasted a lot longer though!



>>On my 83, the tensioner came off without messing with the air pump. I think it is just stuck.


There must be a difference between years, or I am doing something wrong.   I have the tensioner completely disconnected from the engine block (and the puddle of gear oil to prove it.)   But, it is still connected to the air pump at a pivot point.   So, I can swivel the tensioner up and down, but can't get it off the pump.

Man, it's times like this that I wish I had a digital camera...or better yet, a neighbor who is a 928 mechanic!!

Stuck at the tensioner,