Without checking the tension?
I would NOT recommend just tightening it up. My guess would be something is bent in there and although the tracking is fine, it's going to keep getting looser until it skips a tooth or bends something until the belt breaks.

Something's going on in there and the washer isn't the only issue if the belt is showing slack with the engine cold.

 

I know.
Am up from my nap.
There goes the rest of the afternoon.
Looks like the sensor did work at least.

 

Did you check the oil level in it?

 

Shhh, you will scare my zebras.
Just checked, about 10 ml added, I had gear oil in it / sulphur smell / put more for now.

Here's pictures. Tracking a little forward but not close to the tensioner arm as it was prior to putting in the new tan bushings (right ones after all).

Any thoughts.

 

Landseer
i went out to measure that washer for you, however my set-up didn't have one or was missing from when i originally removed it. i'll have to look into it, for my sake anyhow

 

Yup. Ops check on the tensioner warning system: OK.

It does look like the belt's tracking a bit forward on the DS, but looks fine on the PS.

Next thing I would do is remove the belt and check the WP pulley for any wobble/grinding noises or feel.

If that feels OK then what about the belt? I don't see any markings on it at all. Could it be a cheap one or maybe an old one that could have stretched after initial adjustment?

While the belt is off, roll the tension arm shoulder bolt on a flat surface and make sure it's not bent.

Now that you know the warning system was doing it's job, we have to figure out why it didn't maintain tension.

How about the set screw on the tensioner? That wasn't left loose by any chance after you adjusted it the last time, was it?

BTW- I think we figured out that the difference between the bottom of the tension window and about 3/4 of the way up was only a small part of a turn of the bolt, definitely less than the amount of play you can get with one wrench turn (1/4 turn or so?).

 

Its closer to the edge than I'd like. Key is its not touching the pivot arm, but was a few weeks ago before bushings.

Belt is new conti, approx 3 k mi. Scuffing was due to bad tracking due to bad pivot bushings.
Similar to the situation in this thread I think. https://rennlist.com/forums/928-foru...-2-4-07-a.html Imo's post #94 is probably my answer to the tracking issue.

Set screw and lock nut were immobile.

Pump is new Lasso, very smooth.

Don't have the pivot bolt off yet. I have replacements, but this was straight 200 miles ago. Will need to drain the block.

My 86 also had a tension drop after retensioning. Wife called me and I had to put a half turn on it out on the highway somewhere to get her home. Every piece was new on that job. Interesting. Compared to 85 it has a slightly different tensioner arm, improved to align forces to be planar, as I'm sure you know.

Am not a pro. Good thing, I'd starve.

 

Or Park-it.

 

You should be in advertising.

 

NICE

If I can free up the cash I'm going with the Porkensioner this spring. It's right behind brake rotors (too much GO and not enough STOP ) and ahead of the exhaust upgrade I wanted to make. I only have about 20k miles on my last TB/WP job and 3 years but it's just such a complicated setup I worry about it all the time.

Landseer, sorry you have to drain the block again, what a PITA. Hopefully this time it will stick.

 

Only play I could find was a little in the new bushings, a little on the tensioner roller bearings. Very little.

Its buttoned up again, will run it a little while and check it again in a month or two. Hopefully then can make the upgrade. Or park it.

 

Landseer: that washer is 2 mm thick.

 

This used to happen on my former '86. This was after I replaced the water pump and all belt and tensioner bits. Sometimes right aroud 4,000 RPM under full throttle (usually in 3rd or 4th gear), engine fully warmed up it would trigger. Every time it happened, that same day I would check the tension and it was always perfectly tensioned. Eventually, I just gave up on it. Then the PKsn'r came out

Dan
'91 928GT S/C 475hp/460lb.ft

 

Thank you!

So, two things appear to be going on for me.

1. Insufficient / improper tensioning. I was too close to the cam gear by two belt teeth where I had originally chosen to check the belt. This made it look tighter than it was.

Plus, I was adjusting on the mid to loose side of the window, seeing that the belt seemed much tighter around the other parts of its path, assuming equalization would occur.

This time, I went high in the window, but at the right tooth. Also, tensioned, turned motor by hand twice, tensioned, repeated once more. In all, added 1 and 1/2 turns.


2. Tracking: a little play in the tensioner roller bearing. Am going to leave it and observe. This belt got scuffed and edge-worn slightly when I assembled the first time with loose bushings. I won't run it long before checking again.


Porkensioner seems really smart, though I am also interested in what the pros think after their assessment.


Problem with 86 is likely duplicate --- I fixed it with another 1/2 turn out on the road somewhere. I used the same wrong tensioning method on that job, but all parts were new + its the later 86 style tensioner. Will check in the spring. Am getting burned out now. Faster, but burned out.

Update 11/08/2011 ---- Had to retension 86 again. Both cars have been driven about 12,000 miles since this thread started, both are DD's. Will switch to Gates belt instead of current Conti for next round.