Garth S

Thanks for fixing the link ..
Firstly, no slight intended towards your mechanic - looks as it you are in goods hands ( like Allstate ).

As stated in my post, 'some' '86.5's were transition models from the late 16V/early 32V to S4 cars .... from the pics, yours appears to have the S4 tensioner ( brake bleeder style oil taps) - but clearly has a PIVOT BOLT ( early type .... not a pivot stud. If the arm is correct, it has an 8mm offset to correctly center the mid line of the tensioner roller with the plunger/piston of the tensioner body.

The pivot bolt was never intended to have a cross brace - that is reserved for the S4 style water pump that uses a 10mm thread pivot stud ..... so there is a perfectly good reason that you are missing a cross brace .

Note also, that the early style pump has a raised 19mm diameter boss ( guess from memory) that the idler bearing presses onto - and the pivot bolt, which more correctly, is a shoulder bolt, threads into: on the S4/cross brace late generation pump, this boss is machined off, and threaded larger from 8 -> 10mm.

,Again, if your pump is not tapped to accept a cross brace, and has the boss on which sits the idler bearing, it appears to me that all parts are correctly matched.

Back to your problem ..... no doubt your wrench is perfectly correct on the aspect that the pivot bolt backed out - and pressed upon the center cover.

The cure option, from this warm cyberspace armchair, appears to require a fresh TB, shoulder bolt .... and a solid check of tensioner, its arm and tensioner roller: if the pump bearing is as smooth as silk, its OK [ do pull off the idler arm to verify the 'boss' - and that no one has done something goofy with a spacer, etc].

As far as rebuilding a tensioner - very easy to do on the car vs disturbing a perfectly good gasket - if the latter is what you have. The belt does not have to come off for that - but an academic point, as your belt has had a chaffing experience.

Center cover - fix it or replace in kind: just a dust cover.

Take all my comments with a large grain of salt - for while I'm confident that they are accurate based on what shows the one small pic ... it is not to say that someone else previously did a TB service cobbling a variety of parts together .... would need to see the whole front end ...

best of luck ..

PorKen

Gates would like you to have damping...but what they know.

(Gates TB #011, Hydraulic Tensioners)

PorKen

Brake bleeders officially began in '86 (but late '85 have them), along with moving the tensioner body and the arm 'pressure point' 8.5 mm outward to line up the tensioner piston with the center of the roller.

This change also corresponds with the center and 5-8 timing belt covers modified such that the 5-8 cover can be removed without unbolting the alternator and power steering assembly. (Also beginning late '85.)

Note early 1-4 cover, '86 5-8 cover, and brake bleeders on this late '85:

nlneilson

That keeps out more than just dust.
Lost a fan belt and a chunk got under the timing belt and knocked it off four notches.

Third tow on that car but still not too bad for the 7+ years as a daily driver.

______________________________
'79 5spd

86'928S MeteorGrey

I know it's still a swirling controversy, but for me, this is a no brainer.

The oil leaks out of every tensioner (or slackener if you will)
Even experts that take their time find the damn thing out of oil.
The rubber boot fails, the gasket fails, and the clamp fails.
The system then puts more stress on your valuable gears because it does not react quickly enough to compensate for the growth of the engine dimensions when heated... It's just to much of an antiquated pain in the *** to deal with. Do you like tearing your covers off and breaking your back just to be able to check tension of the belt? No? THEN STOP IT!

Call Roger.

Porkensioner, '87 and up Laso water pump with the plastic impeller, new gates belt. make sure your cam, crank, and pump gears are in good shape. Done.
No pivot bolt to bend. No bushings. No worry for belt stretch re-tension.

Visual inspections semi regularly. Check for new Audi tensioner shaft extension. Check for belt debris. DRIVE and feel assured that your belt tension is correct all the time. Know that your water pump will last longer without any extra pressure being exerted on it by a leaky, failing stock tensioner. It's my secret thought that if Porsche had made a better tensioner in the first place, the water pumps probably would have lasted a lot longer to begin with.

This is simply my opinion. Having installed a couple, I will never mess with a stock tensioner again... Initially, it might cost a little more, but if you look at the cost for belt re-tension, and rebuilding of the stock parts, radical cam gear wear and not to mention water pump replacement, the Porkensioner gets even more attractive. Future belt changes will be much less hassle, and replacement cost of the Audi tensioner alone is damn affordable.

You may not have noticed it, but I am an advocate of the PKsnr....

86'928S MeteorGrey

Also (to answer the question of the OP)

YES. If the tensioner looses oil, and the belt tension is already at the high range, the tensioner may not correctly compensate for growing engine dimensions, the added tension can cause water pump failure, pivot bolt failure, and cam gear wear. All of which can cause a loose belt. The scariest proposition is a water pump failure... Talk about loss of belt tension....