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Timing Belt Wear Question UPDATED 2-4-07

 
Old 02-04-2007, 04:06 PM
  #91  
Bill Ball
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Roger - did you comment on the condition of the pivot bolt plastic bushings yet?

Oh, and ANY play in the tensioner roller bearing is bad. These should be real snug, just like a fresh WP bearing. Maybe that's all it is, perhaps along with some looseness in the pivot bushings. I assume the circlip is on the tensioner roller shaft too.

Last edited by Bill Ball; 02-05-2007 at 12:38 AM.
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Old 02-04-2007, 04:17 PM
  #92  
Rick Carter
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Originally Posted by ROG100
The cam gears are looking very good with very little wear on them as is the oil pump gear.
No records of these being changed.
The TB & WP job 1500miles ago states very clearly that the only things changed were the WP & TB. No other parts and the parts cost and labor seem to bear that out.
The tensioner has not been touched at all and the rollers are not new and probably original.

Here's the roller assembly as it came off the car.
Roger,

These at the least should be inspected at every TB service and condition noted. It wasn't on mine at either Stuttgart Motorwerks (Pete Martin) in Hendersonville, NC or Midwestern Autogroup (MAG) in Dublin, OH. It was about 18 months after the TB service at MAG the valves were bent. I also have to take responsibility for not inspecting it myself but I can plead nonprofessional ignorance. Hopefully I've learned from this expensive lesson and by sharing others will not have to go down the same hard road.

As a side note both MAG and Stuttgart Motorwerks are usually well regarded.
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Old 02-04-2007, 04:18 PM
  #93  
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Roger it is likely the crank gear and enough play in the rollers, as well as a tensioner needing rebuild. That belt has taken strain
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Old 02-04-2007, 04:41 PM
  #94  
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I've seen this before on my '85 and it was a combination of a few parts being every so slightly worn out. I had a slightly worn tensioner roller and slightly worn pivot bolt bushings. Each part was so slightly worn that it didn't require changing but as an entire assembly the end play was what cause the belt to be pushed off centre. Sor of like: a little wear here and a little mear there adds to be a significant aomount at the end.
I would replace the tensioner roller with a new one and replace the pivolt bushings too. As soon as there is some play in the tensioner assembly the tensioner rolle will start pushing on the t-belt on a non perpendicular angle and this will make the belt migrate (usually towards the forward direction).

I hope this helps.
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Old 02-04-2007, 04:46 PM
  #95  
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Originally Posted by ROG100
Andrew,
The bolt looks perfectly straight with a steel rule - how bent are we talking?

Garth,
No play on the tensioner roller in either plane.
There is some slight wear in the two non metallic bearing inserts where the pivot bolt passes through.
Maybe .015" total. They will be changed.
BTW, that pivot bolt you pictured may be straight, but it is corroded and probably worn. Hence, it may have play even with new bushings. So, good idea to change that bolt too as you are doing.

I should add that even though I mentioned the WP pulley as possibly being a factor in throwing off alignment of the whole belt, I haven't actually encountred this. So, it's just a hypothetical possibility I threw out. Most likely, as the consensus seem to be, the problem is in the tensioner carrier arm pivot bolt, bushing and roller. Also, it looks longstanding. The shop that serviced this without doing those parts should be run out of business, unless the PO insisted on only doing the TB/WP.
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Old 02-04-2007, 05:32 PM
  #96  
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The carrier arm set up pic in post #85 looks fine: there does appear to be erosion on the bearing surfaces of the pivot bolt as Bill noted - I was just out in the garage checking bushing fit on some old warrior pivot bolts vs a new one. New is good ... but it takes a lot of wear to give significant play in the radial plane.
The circlip behind the tensioner roller being missing is the most common culprit causing the TB to track over the forward edge of the roller; however, the bolt penetration in pic #85 suggests that it is correctly in place.

When the carrier arm, as shown, is bolted to the pump, are the dimple of the carrier arm, center of the tensioner roller, axis of the piston rod, and centerline of the tensioner all sitting on the same vertical plane .... as the center line of the pump pulley?
If not, that often leads to the problem .... again, provided that there is no wobble fore and aft of the carrier arm. Again, it is the circlip and correct spacer that determine this .... which appear correct: hummmmmm .....

Remote as it may be, it is the height of the boss on the water pump that is the last element causing all these parts to sit in the same plane. So, is there any sign that some imaginative sculpting may have been done to this particular pump - to decrease the height? I ask, knowing that we previously caught a 16v to S4 'conversion' .... so maybe someone fixed a damaged boss ?????

A last thought, unless someone already noted it, is that the pump pulley may not be fully pressed onto its shaft .... which would cause the obvious ...

Last edited by Garth S; 02-04-2007 at 05:50 PM.
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Old 02-04-2007, 05:51 PM
  #97  
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Just to reiterate - I am replacing EVERYTHING with new.
Just trying to understand how this situation occured.

The WP is new (will also be replaced) and is correct and has not been tampered with.

The position of the belt on the crank gear was correct and on the oil pump gear and the left cam gear. It should have been correct on the WP becuase the pully keeps it that way.

So we are back to the wear within the tensioner area , rollers, pivot bolt. Or an incorrectly assembled roller assembly.

When all the parts arrive and I can start putting her back together we will see if anything changes.
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Old 02-04-2007, 06:24 PM
  #98  
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Just wondering, does the shaft for the large tensioner roller have the c-clip on it? Otherwise it will be located too far back, there have been 2 cars here in the PACNW with that problem recently.

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Old 02-04-2007, 07:10 PM
  #99  
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Hi Roger,

Very strange, I do not see anything in the fotos or posts to explain the belt mis tracking.

Also strangely the inside of the belt looks pretty new unlike the outside. I still think it had a roller sticking which caused the external belt wear but if they all turn OK now then I have no idea why the belt did not return to tracking correctly.
I assume you did check the water pump roller was turning OK before you removed the WP?

Good luck

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Old 02-04-2007, 07:23 PM
  #100  
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Originally Posted by ROG100
What is causing the belt to track forward or at least be positioned forward and the uneven wear on the rollers?
Dry tensioner. ??
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Old 02-04-2007, 07:37 PM
  #101  
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The tensioner has received no TLC in a number of years and may be original.
Had oil in it.
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Old 02-04-2007, 07:44 PM
  #102  
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Originally Posted by ROG100
The tensioner has received no TLC in a number of years and may be original.
Had oil in it.
Did the main chamber with the washer springs have oil, or just the cavities on the back side? Cracked rubber boot?
I'm just wondering because it seems like most people who post about finding a wandering belt also find a dry tensioner.
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Old 02-05-2007, 12:07 AM
  #103  
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Well, this is a generality, but suits the situation. Rollers which have a slightly concave face will run the belt up one side or the other. rollers that are slightly convex will tend to self center. The reason is beyond the scope of this discussion, but that's the way it works. So, a roller, in this case, a pulley with teeth cut into it with a concave face will route the belt to the side.

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Old 02-05-2007, 12:51 AM
  #104  
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Roger:

I see that you say the belt was NOT forward on the left cam gear. From the pictures, I thought it was. Anyway, if it was mostly forward just on the right cam gear, then that is more evidence that it is the carrier arm bushings, bolt and roller at fault.
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Old 02-05-2007, 06:09 AM
  #105  
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HTML Code:
a roller, in this case, a pulley with teeth cut into it with a
 concave face will route the belt to the side
OK & the reason for the wear on the other side (non tooth) side of the belt?

The tooth side does look very new in the fotos; maybe different in reality!

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