John Speake

Doing a cambelt and water pump change, plus tensioner rebuild.

When I backed of the tensioner bolt to help to allow the belt to slacken off and allow the tensioner arm to be removed, I was suprised at how little the belt tesnion could be backed off.

Having started to rebuild the tensioner today, I found that far from the bimetal stack just falling out of the tensioner body, I had to drift it out from the piston end. I can now see and feel a slight ridge in one place of the inner bore.

I don't think I caused this mark.... is this a problem anyone has experienced ?

I will try taking out the ridge, is this an acceptable fix ?

Bill Ball

The bore is Teflon lined (or some kind of coating), so it can't be repaired if it is damaged.

John Speake

Thanks Bill, although that's not the answer I needed :-(

Speedtoys

928intl?

A new one, is outta the question....unless you think OEM motor mounts are cheap.

Bill Ball

I replaced one with a used tensioner body once when this coating was worn. At the time I was able to just buy the body for not a whole lot. I see 928Intl sells used tensioners complete.

In theory, if you clean it up and reassemble, the tenioner will act like an early (pre-83) tensioner with no hydraulic damping, purely mechanical. It still should have the temperature compensation, as long as the guts can move inside the body. If the area where the valve with its o-ring rides (way down inside) is not worn or ridged, then it could still have the hydraulic damping as well. I'd replace it, but this is another way to look at it. None of this damage will affect whether it leaks or not. That's only determined by the gasket surfaces and the end boot.

I should ask what year is this?

Lizard928

What year is this on John?

dcrasta

Pktensioner..

the flyin' scotsman

John........I have a spare if requierd.

Herman K

Another spare here from a 38k motor

John Speake

Many thanks for all the helpful comments ! You guys are great :-)
It's my 86 Euro S2 16v as per my signature.

I've cleaned everything up fitted the new "O" ring to the piston, cleaned up the ridge (which seems to be at one extreme of the head of the tensioner near the boot end). Evferything seems much freer now, so I will probably leave it as it is.

Inserted some new top hat bushes into the tensioner arm - were much tighter going in than I remember from last time. Sure enough, when test fitting the tensioner pivot bolt it's too tight. Measuring with calipers it seems they are slightly oval in the arm. The old bushes were fine, now many miles on them but I though WYIthere...

Lizard928

John,

Can you get the PN off it or better a picture of it to determine the model you have.

fbarnhill

John,
I have one from an 86.5, you are welcome to it if needed. No doubt I will need your services one day.

Cheers,

John Speake

Thanks for all the offers, I'm pretty comfortable with it now, at either end of the adjustment range, the bimetal stack and spindle drop easily from the assembly.

Colin, the casting number is 928 105 541/R

MainePorsche

I've done a total of 6 cam belt changes over they years (on an 86.5, 91, and one on my current 87 with total rebuilds), and on 3, I have had the stack absolutely stuck. I am a purist, but I think there are to many variables in the original tensioner design to lose oil and then have stack anomalies and bore damage. If I don't like what I find in 22k miles, when I'm due for another cambelt change, I am considering the simplicity of the Porkentensioner. Am I justified to consider this ?

the flyin' scotsman

absolutely.............thats why I have spares, me and every car I work on gets a Porkensioner