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Timing belt potential issue on Holbert car

 
Old 05-16-2005, 01:37 AM
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mark kibort
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Default Timing belt potential issue on Holbert car

I mentioned that i had the timing belt light flash on on the warm up lap of the last race, a quick coast and re-start, seemed to eliminate the problem. hasnt come on since. i did see a need to check the belt tension with my new Kempf tool. It measured out exactly the same as when i installed the new belt.

the problem is that the belt is on the edge of the pulley again (like the last time with the bolt possibly bent and broken after overtighting the 17mm head on the much smaller threaded body) according to the PET, there is a thin washer on the bolt that mounts the tensioner roller. (that upon some discussion, i didnt add to the set of parts on the reinstall) what this washer will do is take up some of the slack in the mounting of the tensioner roller. right now, it moves a few thousands . (like a click click up and down) this means that the tensioner roller assembly is shifting down a few thousands under belt pressure and could be why it is now riding on the edge of the pulley. (almost flush)


does anyone with an S4 or 85 have this thin washer under the tensioner bolt. (not the 1/4" thick washer under the actual roller)

mk
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Old 05-16-2005, 01:59 AM
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Hey, as long as you haven't stripped more than a few teeth, I'd say you're good to go!

Seriously, are you talking about the nylon bushing? Or are you talking about a regular washer? Sorry I don't have PET on this PC othwise I'd post a pic.
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Old 05-16-2005, 02:19 AM
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On the PET, it shows and calls for "washer" and its under the bolt as it goes through the arm, then the thick washer and then the ballbearing clad roller!

i bet thats the issue for the belt creep.

anyone anyone?

MK

Originally Posted by Andrew Olson
Hey, as long as you haven't stripped more than a few teeth, I'd say you're good to go!

Seriously, are you talking about the nylon bushing? Or are you talking about a regular washer? Sorry I don't have PET on this PC othwise I'd post a pic.
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Old 05-16-2005, 08:08 AM
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Like Andrew, I don't have PET on this computer. However, I don't remember more than one washer. An 87 could be different, but I believe you are refering to the bushing Andrew mentioned. Does it look kinda top hat shaped?
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Old 05-16-2005, 09:44 AM
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Does your car have the early style pump ( up to '87) that uses a pivot bolt? - or the S4 style that uses a pivot stud? - for the carrier arm. Also, is the washer referenced on the carrier arm pivot position ( which secures the idler roller)? - or the through bolt that secures the tensioner roller?
I think you meant the latter - and if so, the washer shown in PET is just a lock type - it should not act to locate the tension roller.
If the belt is moving forward, I'd first suspect wear in the two carrier arm bushings, then a bent bolt ( if your engine is a '86-'87 hybrid), and finally, a worn crank gear.
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Old 05-16-2005, 10:12 AM
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Whatever you do, stop that belt from moving forward....that's what preceded mine slipping off one of the cam gears.
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Old 05-16-2005, 10:20 AM
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Ok-

Is it the number 3 in this picture?
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Old 05-16-2005, 11:10 AM
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The #3's are the bushings. I have the bushings and the #12 thick washer. You scared me for a minute...I thought I might have to pull the roller arm apart and stick another washer on there.
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Old 05-16-2005, 11:12 AM
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In Andrew's picture the only other washer I see is the #45.
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Old 05-16-2005, 11:34 AM
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Oh yeah... My pic is for an 87 S4. Sorry Dave, didn't mean to scare you.
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Old 05-16-2005, 11:43 AM
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Originally Posted by Andrew Olson
Oh yeah... My pic is for an 87 S4. Sorry Dave, didn't mean to scare you.
I actually saw this post last night before going to bed and had trouble falling asleep because I couldn't remember how that arm was attached. I'm a deeply troubled man.
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Old 05-16-2005, 11:50 AM
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Mark I had a factory fresh '85 and I do not recall any washer there.
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Old 05-16-2005, 11:57 AM
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I guess the question is which tensioner is on the Holbert car? By the looks of things, if its the 85-86 tensioner, there is no washer as seen in BigDave's picture. But if it's an 87 tensioner, there is. Seeing that the Holbert car was basically one of the first S4's off the line - or even pre-production, I would think they might have used/adapted the 85-86 tensioner. In either case, based on your description, it does sound like you need that washer (#45).
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Old 05-16-2005, 02:29 PM
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YES< thats it and thats the picture #45!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

so, you can see, without the washer, the entire assembly as it attaches to the water pump will not have the proper thickness. the bolt bottoms out and thats how they get the clearance of the arm attached to the water pump. so, if you can picture the washer missing, the entire arm moves ever so slightly ("click, click", maybe a few thousands) but, thats enough to change the position of the belt and how it runs over all the pulleys.

BTW, my set up is mostly S4, but the waterpump is early (85) style im not sure about the other parts.

does the S4 also use this washer with the bolt that attaches the tensioner arm but goes throught the idler roller?

#45 is the part!!!!

MK
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Old 05-16-2005, 02:38 PM
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Mark-
I think the issue is the block. Obviously you have the s4 block which is different from the 85/86 block. But the tensioners I think are pretty much the same (correct me if I'm wrong here) between 85/86 and the S4s. But if for some engineering reason they had to make the bolt hole shallower than the 85-86 block, I can see why they might add the washer to help fudge the setup without comprimising integrity of the system. Iit's a cheap solution compared to spec'ing a new length bolt to fit the hole.

Sounds like you need a washer my friend.
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