Gary Gaukler

Hello,

I am doing a belt R&R on my 86 951. After taking the balance belt off, I noticed that the lower balance belt sprocket sticks. I cannot rotate the sprocket using just my fingers. It does rotate when I use a 17mm wrench on it though.

The upper balance belt sprocket moves freely, as does the tensioner roller.

So I am thinking there is something wrong with the lower balance shaft. Can anyone confirm or deny that the sprocket should move freely when aplying finger strength?

Thanks in advance!

Gary

xsboost90

do you have the gear off? I know that when the gear is off the shaft can move front to back and will bind but usually when you put the gear back on it "centers" it and it'll spin fine. Should be able to spin easily w/ the sprocket gear on there.

Gary Gaukler

Thanks. Sprocket gear is still on; I didnt touch anything besides removing the belt.

Looking at receipts from the PO, it seems that one of the balance shafts was replaced 5 years ago because it was seized. P/N 94410202300. Is that the lower balance shaft? If so, I guess they didn't install it correctly...

Why do I have the feeling this is going to be expensive?

Tom M'Guinn

You should be able to turn them easily by hand. If you need a wrench, something is not right. Sometimes it can be as simple as re-aligning the front bearing piece.

PorscheDoc

I just pulled apart a customers track car and found the same thing on the upper balance shaft. I pulled the turbo to get the upper balance shaft cover off, and found the bearing was literally coming apart (the surface was completely gone in a few places). Needless to say, the BS is shot.

I would pull it apart and see what is going on, something isn't right.

2bridges

X10 - you have a problem

xsboost90

btw- you can pull the upper or lower balance shaft w/o pulling the turbo or very much apart. Its a pain but i did both on sam's car to diagnose a noise and worked out fine. Lower one can come out by pulling the ps mount brace and some little stuff out of the way not too terrible.

PorscheDoc

Lower one yes, but I dont see how you got the bolts to clear the turbo on the upper cover. Turbo removal is only about an hour anyway, so it isn't a big deal, then you can do the OAS seals while you are in there

hosrom_951

I could not access most of the bolts for the lower balance shaft.

Needless to say, it would be tricky as heck to fit a torque wrench in there

xsboost90

dont ask me how but i got the top one off w/o pulling the turbo or the shields - there are like two bolts that didnt come right out and i got them loose and pulled them w/ the cover. ONly took about 35 minutes to pull the intake and top balance cover this way. Now this was a dry turbo so maybe there is less in the way somehow.

edit-ok i must have pulled the heat shield but thats only a couple 10mm bolts.

Chris White

The most common cause for binding on the lower balance shaft is the incorrect tightening of the balance shaft cover to power steering brace (it uses the 4 mounting bolts on the balance shaft cover and one bolt to the power steering extension. Loosen the one bolt that connects to the power steering bracket and I will bet your shaft will free up.
You can thank me in the morning….

Gary Gaukler

Thanks for all the helpful replies! I haven't been able to get under the car since then, so unfortunately I have nothing new to report.

Chris White - what/where exactly is the balance shaft cover? Do I have to remove the sprocket to get to that? Or is it out in the open?

Thanks again!

Gary

Chris White

The balance shaft cover is the part that actually holds the balance shaft in place. It covers about 2/3rds the length of the engine. In the pictures above it is missing in the lower balance shaft picture and shown prominently in the upper shaft picture. It is out in the open.

Tom M'Guinn

This picture shows the cover in all its uncluttered glory... It's the lighter colored piece running down the side of the motor.

Phil R

I'm having the same problem with a binding lower balance shaft, actually I just found it today. I was very worried that it could mean a big big problem but this thread is making me feel a little better. at least i have a couple things to check before i freak out.