Timing Belt Replacement
03-11-2002, 08:38 PM
#1
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Timing Belt Replacement
I started the replacement of the timing belt today, first time for me on the 32V 928. I've done other cars. The info on the web is just great, probably even better than in the shop manuals. The belt was replaced somewhere/somewhen by a previous owner and they marked the 45 degree position on the cam pulleys. When I had the timing at TDC, the marks for that lined up OK, as they did when I set it at the 45 degree mark, but I notice the rotor on the passenger side was almost dead on at the 3 o'clock position, but the driver side was at about the 2:30 position. The car was/is running fine. Is it possible the last time the belt was changed that it was installed one tooth off on the driver side? Would it still run good? Should I be concerned about the position of the rotor, or just the timing marks?
TIA
Glen
TIA
Glen
03-11-2002, 09:38 PM
#2
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Glen,
can't help on the cam timing issue (maybe Jay will pop in on this) but I'll loan you the t-belt tension tool. I'm out tomorrow so can't drop it off until Wednesday at the earliest. Let me know.
Jim
can't help on the cam timing issue (maybe Jay will pop in on this) but I'll loan you the t-belt tension tool. I'm out tomorrow so can't drop it off until Wednesday at the earliest. Let me know.
Jim
03-11-2002, 10:05 PM
#3
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Glen,
With the crank pulley mark, at 0/T (TDC), the #1 piston should be at TDC on compression stroke. The easiest way to tell is the rotor should be pointing (ready to fire) at the #1 cylinder spark plug wire (passenger side) and the marks on the cam sprockets should line up with the marks on the flange.
Yes, both rotors should point at the 3-o clock position. It is possible for one cam to be out of timing (or phase) and the car still runs. Turning the crank to the 45-degree position is a confusing step to some. Some cars don’t even have the 45-degree mark on the crank. The purpose of the 45-degree setting is for removing, setting, and turning the cam shafts 360 degrees without damaging the valves If all your doing is changing the timing belt, and your not turning the cams or the crank with the timing belt removed, there is no need to set the crank at the 45 degree mark.
Good Luck
Steve C
The Great White
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With the crank pulley mark, at 0/T (TDC), the #1 piston should be at TDC on compression stroke. The easiest way to tell is the rotor should be pointing (ready to fire) at the #1 cylinder spark plug wire (passenger side) and the marks on the cam sprockets should line up with the marks on the flange.
Yes, both rotors should point at the 3-o clock position. It is possible for one cam to be out of timing (or phase) and the car still runs. Turning the crank to the 45-degree position is a confusing step to some. Some cars don’t even have the 45-degree mark on the crank. The purpose of the 45-degree setting is for removing, setting, and turning the cam shafts 360 degrees without damaging the valves If all your doing is changing the timing belt, and your not turning the cams or the crank with the timing belt removed, there is no need to set the crank at the 45 degree mark.
Good Luck
Steve C
The Great White
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
03-11-2002, 10:30 PM
#4
Glen,
Just to confirm that the car will run with one tooth out on the cam drive pully.
When I had my belt changed my mechanic found this problem. After the change when I got the car back it ran a lot better, needless to say.
Jim, good to know that you can drop the belt tensioning tool off to friends in need, I will let you know when you can drop by Australia, not too far to travel!
Tails 1990 928 S4
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
Just to confirm that the car will run with one tooth out on the cam drive pully.
When I had my belt changed my mechanic found this problem. After the change when I got the car back it ran a lot better, needless to say.
Jim, good to know that you can drop the belt tensioning tool off to friends in need, I will let you know when you can drop by Australia, not too far to travel!
Tails 1990 928 S4
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
03-11-2002, 11:06 PM
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The valve spring tension on the Cams may have an impact on the Cams and their positioning when setting the Cams to the 45 degree mark.
When I replaced my Tbelt (and then my race cams back to stock cams) last summer - I found that the 5-8 bank would always align itself to a 'less than' 3 o'clock position. I checked, and triple checked the readings and positions to be certain that I wasn't missing the point so to speak. This occured to me under both scenarios....that being said, I firmly believe that the 'mid' position of the crank on the lifters/valve springs created the tendency for the cam(s) to roll forward - which in turn created the off from normal 3 o'clock final rest position.
btw - after the above mentioned maintenance, must of got lucky - Dyno results indicate 273 HP, 281 Torque on a Dynojet. The results seem pretty comparable to other Automatic S4's.
I would highly recommend not just double checking but TRIPLE checking all of the settings. The results of mis-positioning can break you. (*I measured and cut that board twice - and it's still to short syndrome*)
hth-
When I replaced my Tbelt (and then my race cams back to stock cams) last summer - I found that the 5-8 bank would always align itself to a 'less than' 3 o'clock position. I checked, and triple checked the readings and positions to be certain that I wasn't missing the point so to speak. This occured to me under both scenarios....that being said, I firmly believe that the 'mid' position of the crank on the lifters/valve springs created the tendency for the cam(s) to roll forward - which in turn created the off from normal 3 o'clock final rest position.
btw - after the above mentioned maintenance, must of got lucky - Dyno results indicate 273 HP, 281 Torque on a Dynojet. The results seem pretty comparable to other Automatic S4's.
I would highly recommend not just double checking but TRIPLE checking all of the settings. The results of mis-positioning can break you. (*I measured and cut that board twice - and it's still to short syndrome*)
hth-
03-13-2002, 06:05 AM
#7
Jim,
Suggest bl..dy big tyres that take plenty of air as it is a long way 'down under'.
Watch out for 'White Pointer Sharks' not as fast as the land sharks, but their bite is a killer.
How is the rebuild going?
Best regards,
Tails 1990 928 S4
<img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" />
Suggest bl..dy big tyres that take plenty of air as it is a long way 'down under'.
Watch out for 'White Pointer Sharks' not as fast as the land sharks, but their bite is a killer.
How is the rebuild going?
Best regards,
Tails 1990 928 S4
<img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" />
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03-13-2002, 05:51 PM
#8
Three Wheelin'
When doing my TB, I noticed that my pass. side cam was retarded one tooth. I reset it, checked and re-checked the position. I was only relying on the notches on the cam sprockets and really did not study the rotor positions.
Since I have run the engine some since then, I will check the notches and rotor positons again this weekend.
Since I have run the engine some since then, I will check the notches and rotor positons again this weekend.
