8 cylinder front engine iconic vehicle
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By Bertrand Daoust
#149689
Hi,

I put new cam gears (after market) and now the belt is tracking a bit more to the front of the cam than it used to with the old ones.
Should I worry with this?
I turned the engine (by hand) many times.

I also put back the stock tensioner with new boot, tensioner bushings, tensioner main roller.
I didn't change the water pump (Laso, plastic impeler - new from 2017). No leak and no play.
I adjusted the belt tension (Kempf tool). It's on the high side a bit.
The timing as not been adjusted yet.

Thank you.

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By smiffypr
#149693
Is the pivot bolt for the tensioner arm completely straight? (Later cars have a support for the end of this pivot because they tend to bend). Also, is the belt rubbing on the tensioner arm or on the dished washers either side of the crankshaft pulley?
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By worf
#149702
Bertrand Daoust wrote: Sun May 15, 2022 7:37 am I put new cam gears (after market) and now the belt is tracking a bit more to the front of the cam than it used to with the old ones.
Should I worry with this?
Did you mess with the crank gear at all?

Have you installed the roller carrier brace yet?

Do you have a picture of your assembled roller carrier?

Do you have a picture of the belt tracking on the tension roller?
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By Bertrand Daoust
#149704
I think it's straight.
I have the support installed.
I don't see the belt rubbing anywhere...
Thank you.

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By Bertrand Daoust
#149706
I didn't remove the crank gear.
Unfortunately, I don't have a pic of the assembled roller carrier.
Thank you.
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By Bertrand Daoust
#149708
Would a pic of the belt on the crank gear would be useful?
I can remove the balancer and take a pic.
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By worf
#149712
Bertrand Daoust wrote: Sun May 15, 2022 9:53 am Would a pic of the belt on the crank gear would be useful?
No. What would be useful would be an observation of if the crank gear is "loose" on the crank and possibly slipped forward a millimeter or two during disassembly.

Belt tracking is controlled by the position of the main tension roller and the crank gear (and it's "big washers.") Not much else matters.

The main roller is positioned on the carrier by the nut, bolt, washers, and the c-clip. On the leading side should be just the bolt head. On the engine side, the nut and both washers.

Your tensioner is the the original? Not one you bought used when you decided to uninstall the PK'T?

Tell me about the pivot bolt. This has always been installed on the water pump? Or did you install it post-PK'T-ectomy?
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By worf
#149713
I can't tell for sure, but it looks like the belt may be tracking forward on the tension roller too.

Make an observation of belt-on-roller tracking (with inspection mirror if required) and report back.
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By Bertrand Daoust
#149716
I need to go out for a while.
I'll be back later this afternoon and report back.

Thank you guys!
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By Benno
#149760
Bernard, I had a similar problem where my TB was 'walking' back and forth on the cam gears. Here are some videos of that:



The cause in my case was that the crank gear thrust washer and harmonic balancer were not properly seated against the crank gear. I would verify you have the thrust washer and the harmonic balancer properly seated.

As I look at your photos you do not have the AC pulley (3.6mm) or the Accessory Bell Bell (4mm) installed. Did you use those to compress the harmonic balancer and thrust washer against the crank cog? If not then I would recommend locking the flywheel and recompressing those two items.
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here is a cross section of the assembly for reference. It is not possible to compress the damper and washer without both pulleys installed.
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By Bertrand Daoust
#149768
Ok, I'm back...

Dave,
The tensioner is the original one.
The pivot bolt is on the pump since new (2017). Never touched it.
The nut, bolt, washers, and the c-clip are at the right place (that I remember!)
The belt is definately tracking forward on the main tensioner roller.

The more I look at it, the more I begin to think that it might be that the belt was just not positioned properly at first. It' too much forward everywhere. Crank gear, both cam gear, tensioner main roller, water pump...
I think I will re-do the whole thing making sure the crank gear is well seated and the belt at the right place everywhere and rotate the engine (by hand) many turn and see...

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Thanks guys!
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By worf
#149777
Bertrand Daoust wrote: Sun May 15, 2022 4:15 pm The more I look at it, the more I begin to think that it might be that the belt was just not positioned properly at first. It' too much forward everywhere. Crank gear, both cam gear, tensioner main roller, water pump...
I think I will re-do the whole thing making sure the crank gear is well seated and the belt at the right place everywhere and rotate the engine (by hand) many turn and see...
No need to “redo” anything. @Benno jumped to the end of one of the logic trees and with my questions answered, I agree with his speculation.

It is possible that once you torque the crank pulley bolt with all the accessories and rotate the engine a 1/2-dozen times that the belt will track further “engine”-ward.

If you don’t want to take the risk of having to disassemble, then just to the torquing now, without worrying about belts, covers and such. Tighten the flywheel lock then with balancer, a/c and main pulley installed, torque the crank bolt. Turn the crank a 1/2-dozen times and see where you end up.
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By worf
#149778
Or just loosen the tension a bit and wiggle the belt further back on all the gears. Then retension and check again.
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By Bertrand Daoust
#149782
I just tried repositioning the belt and turn the engine (by hand) few times and the belt wants to go forward again.
I will try again but with the all the pulleys in place like Benno (and Dave) suggested.

It should work... :)
Thanks guys!
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By Bertrand Daoust
#149839
I tried with all the pulleys in place and the crank bolt torqued but still have the belt on the cam gears at the same place or so (as pics 1 t 4).
The belt is now flush with the crank gear.

I took a look at my old tensioner roller and notice that the belt ran at the same place (or so) as on the new one. It wasn't right in the middle either.
I also took a look at my old cam gear set and at another used set from another 928.
I can see that on mine the belt was a bit not as forward but on the other one it was maybe a bit more forward...
I guess I'll live with it!
I will post pics of the used cam gears and roller tonight

Thanks guys.
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By worf
#149845
Bertrand Daoust wrote: Mon May 16, 2022 6:40 am I took a look at my old tensioner roller and notice that the belt ran at the same place (or so) as on the new one. It wasn't right in the middle either.

I can see that on mine the belt was a bit not as forward but on the other one it was maybe a bit more forward...
I guess I'll live with it!
Then “a bit forward” is just where it wants to run. It’s fine (as long as all the pieces are good and that seems to be the case.)
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By Bertrand Daoust
#149853
Thanks Dave.

Next step, timing with the 32VR.
A first for me, so might have few questions.
We'll see...
Thanks again.
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By worf
#149950
The key will be, through the vent holes in the side covers, seeing how the belt tracks after it's turned a couple of hundred times.

Last check before you put on the center belt cover:

Use an inspection mirror and see - as best as you can - if the "cup" of the roller carrier, the push rod/spring assembly and tensioner body are all in nice straight line.
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By Bertrand Daoust
#152160
Just a little update on this.
I went for a ride (+/- 200 km).
It's about 1.5 to 2 mm from the front of the gear.
So, everything's fine.
The tensioner is leaking a bit but I can live with that...
Now, we're ready for all the 928 event this summer.
Camp 928, PVGP, Frenzy...
And I'll have all the time as I'm retiring in two days! :thumbup:

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Last edited by Bertrand Daoust on Sun May 29, 2022 5:17 pm, edited 3 times in total.
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By worf
#152197
Bertrand Daoust wrote: Sun May 29, 2022 5:06 pm It's about 1.5 to 2 mm from the front of the gear.
Check it periodically(*) and make sure it's stable at that measurement.

(*) I'd do this at each gas fill for the next 2 or 3 tanks.

That distance is not where I'd like the belt to track on the cam gear. A lot of eyeballs were on the components so I doubt anything's wrong. But making sure the belt isn't wandering forward is the final test.

Maybe you just have a crank that's at the long end of the bell curve.

Have you ever had the clutch out?
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By Bertrand Daoust
#152233
Thanks Dave.

I'll keep an eye on it for sure!

Sorry but what clutch do you mean?
My car is an auto.
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By worf
#152236
Bertrand Daoust wrote: Mon May 30, 2022 5:25 am My car is an auto.
Doh! Stuck in my head that you had a GT.

Fine.

What is your flex-plate migration risk mitigation strategy?
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By Bertrand Daoust
#152263
I have PKlamp installed since many years.
Didn't move since.
I'm checking it regularly.

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