ArcticSteve

I've just replaced my oil sleeve and seal behind the crank gear and have replaced all the rollers, etc. on my 1990 S2

I installed a brand new Gates 152 cam belt. Spring tensioner fully retracted. Didn't think I was gonna ever slip the bastard over the cam gear. However, just as I was giving up it slipped on. Very tight fit.

Then following the Arnnworx instructions, I mounted the gauge and reference bar and got .230 . Although, this will vary depending on how "deep" into the top of the water pump pulley one goes with the reference bar. The instructions are a little vague on this part.

So the value I'm looking at is .230 (tensioner fully retracted) plus .165 (for reasons I don't understand other than the "reference bar") and I then removed reference bar and set the tension to .385

QUESTION/ISSUE.

If I had wanted to I could have let the tensioner gear/roller out more. It was in no way all the way out. But I keep reading on other threads that these spring tensioners are meant to be just let out fully and the locked.

Unfortunately being a NOOB I didn't experiment around and see if the tensioner was all the way out when I retracted it originally to remove the old belt.

Since I haven't got the balance belt on yet I haven't rotated the belt a revolution or two as the crank is still locked. But I'm certainly not able to twist it 90 degrees up on the upper side with separator bar off and idler pulley removed as it is presently. 45 degrees yes, not 90. Is the S2 belt being wider make a difference?

So why use a tension gauge and just simply release the spring tensioner fully and leave it at that? Although, if I did release the tensioner fully it would be tighter than it is now.

So I like the 920x, but confused on how it actually knows what the real value should be by virtue of this thin metal bar. As is stands now the 920x is telling me that the spring tensioner fully released is way too much tension and the finger twist 90 thing is not happening. Although, again, I have not rotated the belt. Perhaps when I do things will change.

Thanks, Steve

Joe Jackson

Make sure you have the belt sitting properly on all of the sprockets. It should not have any appreciable tension when mounted with the spring tensioner fully retracted. You should be able to twist the belt 90 degrees easily prior to releasing the tensioner.

I've never used the 920X (only ever use the real P9201) so I can't comment on the rest of your post.

ArcticSteve

Thanks. I'll get the balance belt on and then rotate the engine and see better how the cam belt is sitting.

John_AZ

The "mechanical spring tensioner" will not be accurate if belt tension on the passenger side is over tightened. (too tight). It will cause the cam belt to be overtensioned--too tight and burn out the WP pully bearing or worse.

This is the design flaw if you only use the spring tensioner.

Per Porsche: When using the "mechanical spring tensioner" the engine is set at TDC.
Do not rotate the crank ccw.

If you followed these instructions, the cam belt would probably be too tight. I have found I needed to turn my crank ccw about 5* or 1/2 cam gear tooth to be accurate. I have the spring tensioner.

Use the Arnnworx tool and then try the WP pully test. A new belt is tensioned tighter than a used. Recheck your new belt after about 500 miles of driving when it has worked into the gears.

Joe Jackson

Don't bother installing the balance shaft belt until you get the timing belt sorted out. You'll just be removing the balance shaft belt if you find a problem (and I'm certain that there is a problem). Install the crank pulleys even if it's just temporary and unlock the crank so that you can verify the timing belt is installed properly and that the engine rotates like it should.

ArcticSteve

JOHN, awesome, much appreciated.

ArcticSteve

Joe, OK I'll resolve the cam belt first. Thanks

ArcticSteve

I'll start by saying that I have bought a few of Arnnworx tools and found the products great and service fantastic.

However, I didn't really get along with the 920X. If I lived in the States I would have ordered Bruce's new belt gauge, but we have a postal strike happening so anther time.

Essentially, after a zillion adjustments, I found that adequate cam belt tension was obtained by letting the spring tensioner all the way out and then backing it back 1/2 dial or 50 degrees on the 920X. So for viewing very small adjustments on the tensioner the 920x came in handy.

I've set the tension so I can move the water pump with a "strong hand", no clacking sound and no visible flapping of the belt. Belt does not quite turn 90 degrees on top span with separator bar off and idler off. It never did, even with no tension.