.......

 

Mine are no longer there with the Porkensioner. 25k miles/3 years of hard driving and counting...

Dan
'91 928GT S/C 475hp/460lb.ft

 

Those do seem a good idea, especially in the event of failure of other components like shoulder bolt and water pump. They will let the crank engage a sloppy belt. I prefer the 2-roller version.

 

All I know for sure is that 928 105 067 00 is a single roller idler, as used on my '93. And my 90GT (engine # 916, born-on date 1-10-90) has a double roller idler, part # 928 105 067 01.


Beyond that, the PET biopsy sez:


1978-1982, up to M 81D 0693: guide rail (no rollers on it). 928 105 567 01.



1983 to 1986: 928 105 067 00, single roller guide, starting on early 1983 M28.19, .20, .21, and .22 starting with engines M 81D 0694 (manual) and M81D 5431 (auto).

This apparently was used in conjunction with 928 105 147 03, the 78-82 rear center TB cover.


1987: Also 928 105 067 00 single roller guide (but different rear TB cover - 928 105 147 05), starting on M28.41 and M28.42 engines, M 81H 01233 and M 81H 08036, respectively

1987-1990: 928 105 067 01, double roller guide, starting on M28.41, .42, and .47 engines, and using rear center TB cover 928 105 147 07

5-speed: M 81H 01234 to M85L 01162
Automatic: M81H 08037 to 81L 51964


1990-1995:
Back to the single roller 928 105 067 00, and the -05 rear center TB cover..
5-speed: M 85L 01163-on
Automatic: M81L 51965-on

 

The last TB job I did on both 88SE and 90GT both those rollers (on both cars) were rusty all round indicating a long time since the belt had touched them. Three would not turn at all by hand and one only barely by hand.

Probably a waste of time and money but I did change the bearings in all 4 prior to reassembly.

 

I've only done 3 TB/WP jobs- all on S3s. But I found the same thing. I think it's the solution to a problem that doesn't exist. If the belt hits this I think you've got some other problems already and they're problems that these rollers are not going to help.

 

took them off when I installed the Porkensioner and yes they were hard to turn.......they've been in the parts bin since.....5 years now.

 

The plastic guide on the early cars is no longer available new so it cracks and falls of.
On later cars the one and two roller guides seize up.
Porsche returned to a single roller for the last years of production.
If it works leave it there. If you have the PKensioner leave it off.
Replace the bearings if it makes you feel better.

 

^^^ That would be a good blurb to add to the PKTensioner guide. Ver 1.3 says "Optional: remove crank gear idler pulley(s) and bracket" but doesn't say why. And there you go, Bob's your uncle.

 

Like anything else, if you don't follow factory t-belt procedures and leave rusty or seized rollers, they cannot help you. I have always isntalled new bearings. I PITA to be sure, but I do it anyway. Maybe there is no real-world gain in having them.