View Poll Results: What is causing the tracking issue?
Surfridermason wouldn't approve of this poll because no one can be insulted by it. (Hi Mase 
)
)
19.05%
Voters: 21. You may not vote on this poll
Diagnose this TB tracking issue for fun and profit (except the profit)
01-28-2008, 08:17 PM
#46
Fleet of Foot
Rennlist Member
Rennlist Member
Hi everyone - just came in from the garage and this is what I found:
1) The shoulder bolt has a slight bend to it
2) The tensioner arm bushings were worn and partially gone - left "shiny" wear areas on the shoulder bolt
3) Believe it or not, the belt wore a slight groove in the backside of the tensioner arm!
4) The tensioner roller is bad, very bad - when I spin it, it squeaks and has a rough feel to it
5) The tensioner boot crumbled when I removed the tensioner arm
6) The grounding strap was broken
And finally, the waterpump is a Laso unit....
I will be replacing all bushings, rollers, etc. to get the TB system back on spec.
Should I leave the waterpump in or replace it now with a "non-Laso" rebuilt or new unit?
Pictures to follow - thank you for your input!
Adam
1) The shoulder bolt has a slight bend to it
2) The tensioner arm bushings were worn and partially gone - left "shiny" wear areas on the shoulder bolt
3) Believe it or not, the belt wore a slight groove in the backside of the tensioner arm!
4) The tensioner roller is bad, very bad - when I spin it, it squeaks and has a rough feel to it
5) The tensioner boot crumbled when I removed the tensioner arm
6) The grounding strap was broken
And finally, the waterpump is a Laso unit....
I will be replacing all bushings, rollers, etc. to get the TB system back on spec.
Should I leave the waterpump in or replace it now with a "non-Laso" rebuilt or new unit?
Pictures to follow - thank you for your input!
Adam
01-28-2008, 08:37 PM
#47
Burning Brakes
Join Date: Jan 2002
Location: Springfield, MO
Posts: 842
Likes: 0
Received 0 Likes
on
0 Posts
I voted "None of the above". Had the same thing happen to a previous 928 and it was the two "#3's" in that diagram someone posted. Those bushings wore out on mine and allowed the tensioner to tilt enough to cause the belt to do exactly what yours appears to be doing; rub against the tensioner arm.
Worn bushings --> Tensioner slightly tilts --> Belt creeps --> Belt rubs tensioner arm --> Shaft bolt bends --> Belt shreds --> Valve job.
An occasional peek down through the passenger side inspection hole can help detect a creeping belt. The belt should not be riding at the front edge of the cam gear.
01-28-2008, 08:41 PM
#48
Fleet of Foot
Rennlist Member
Rennlist Member
Same here.
Worn bushings --> Tensioner slightly tilts --> Belt creeps --> Belt rubs tensioner arm --> Shaft bolt bends --> Belt shreds --> Valve job.
An occasional peek down through the passenger side inspection hole can help detect a creeping belt. The belt should not be riding at the front edge of the cam gear.
Worn bushings --> Tensioner slightly tilts --> Belt creeps --> Belt rubs tensioner arm --> Shaft bolt bends --> Belt shreds --> Valve job.
An occasional peek down through the passenger side inspection hole can help detect a creeping belt. The belt should not be riding at the front edge of the cam gear.
01-28-2008, 09:07 PM
#50
Burning Brakes
Join Date: Jan 2002
Location: Springfield, MO
Posts: 842
Likes: 0
Received 0 Likes
on
0 Posts
Luckily, I caught mine too. The glaring downward spiral was unnerving.
01-28-2008, 09:58 PM
#51
Craic Head
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
It never ceases to amaze me how these supposedly 'delicate' or 'hard to maintain' cars can run with only 3/4 of their belt left, a bent shoulder bolt and a belt tension reading of 3.0.
I am duly impressed. So the answer was 3 none of the above.
Adam, you're saying everything was installed properly it was just worn out bushings that led to the other problems because of lack of attention?
FWIW: I know you and your attention to detail, if you do the WP for no other reason than to replace the bolts and get some anti-seize in there, it will be worth it.
I am duly impressed. So the answer was 3 none of the above.
Adam, you're saying everything was installed properly it was just worn out bushings that led to the other problems because of lack of attention?
FWIW: I know you and your attention to detail, if you do the WP for no other reason than to replace the bolts and get some anti-seize in there, it will be worth it.
01-28-2008, 10:10 PM
#52
Rennlist Member
Join Date: May 2007
Location: Not that far from the Jersey Shore
Posts: 323
Likes: 0
Received 0 Likes
on
0 Posts
Mike,
Everything was in its place. I think the last time the covers were off, only the TB belt and the WP were replaced (laso?). Everything was old, dry and brittle - most likely a short-cut by the last mechanic.
You know I am sitting here debating on whether to pull the WP or not. Should I wait a couple of years for the the next TB replacement or just go ahead and replace the WP now.....
...........with anti-seize on the bolts, of course!
Everything was in its place. I think the last time the covers were off, only the TB belt and the WP were replaced (laso?). Everything was old, dry and brittle - most likely a short-cut by the last mechanic.
You know I am sitting here debating on whether to pull the WP or not. Should I wait a couple of years for the the next TB replacement or just go ahead and replace the WP now.....
...........with anti-seize on the bolts, of course!
01-28-2008, 10:17 PM
#54
Craic Head
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
Mike,
Everything was in its place. I think the last time the covers were off, only the TB belt and the WP were replaced (laso?). Everything was old, dry and brittle - most likely a short-cut by the last mechanic.
You know I am sitting here debating on whether to pull the WP or not. Should I wait a couple of years for the the next TB replacement or just go ahead and replace the WP now.....
...........with anti-seize on the bolts, of course!
Everything was in its place. I think the last time the covers were off, only the TB belt and the WP were replaced (laso?). Everything was old, dry and brittle - most likely a short-cut by the last mechanic.
You know I am sitting here debating on whether to pull the WP or not. Should I wait a couple of years for the the next TB replacement or just go ahead and replace the WP now.....
...........with anti-seize on the bolts, of course!
Do you think that arm is OK or are you going to replace it?
01-28-2008, 10:18 PM
#55
Rennlist Member
If it tracked that way a while, plus if it sat for any period of time, I'd strongly consider replacing.
Water pump bearing, seal and impeller don't seem overengineered on most cars, this included. If it goes after retensioning, which can happen, you might be re-belting it as well.
My PO retensioned on a car that sat for a while. Pump failed quickly thereafter. Right after title changed hands.
Water pump bearing, seal and impeller don't seem overengineered on most cars, this included. If it goes after retensioning, which can happen, you might be re-belting it as well.
My PO retensioned on a car that sat for a while. Pump failed quickly thereafter. Right after title changed hands.
01-28-2008, 10:25 PM
#56
Rennlist Member
Join Date: May 2007
Location: Not that far from the Jersey Shore
Posts: 323
Likes: 0
Received 0 Likes
on
0 Posts
I think this car sat for some time. I picked it up from a shore town which is the reason for the salt-like deposits on the TB/WP parts.
I think the arm is strong enough for future duty based on the slight amount of wear - I'm open to suggestions.
Should I replace the tensioner arm?
Adam
I think the arm is strong enough for future duty based on the slight amount of wear - I'm open to suggestions.
Should I replace the tensioner arm?
Adam
01-29-2008, 01:30 PM
#58
Craic Head
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
I'd probably re-used that arm too. I can't really tell how deep it's cut in, but the stress on that arm isn't front to back, it's lateral. I can't imagine it's weakened enough by that groove to have an effect.
01-29-2008, 07:01 PM
#60
Under the Lift
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Yes, but washer #12 omitted from between the tensioner arm and the idler roller on the WP will change the position of the entire arm, moving it inward toward the WP, and cause the outside edge of the belt to rub on the arm as shown. That will also throw the tensioner roller off it's correct track.
Additionally, the circlip was already inplace on the roller as shipped from the supplier in both instances that i did my timing belt, once from 928intl and the other time from 928SP. I can't see why anyone would remove the circlip if the roller is already shipped with it inplace.
Additionally, the circlip was already inplace on the roller as shipped from the supplier in both instances that i did my timing belt, once from 928intl and the other time from 928SP. I can't see why anyone would remove the circlip if the roller is already shipped with it inplace.