Solving the problem of squeaky/worn pulleys on the old M60 V8s

[genphreak]

On an M60 (e34 540i), I have to replace the pulleys and belts cos they're pretty noisey. And once that one's done, there's another one to do.

So I jumped online to order the bits and pieces. Had a look at the ETK, noticing that on the later V8s they introduced new tensioner designs and configurations (on both the AC and the main serpentine belts). The later designs even look to be similar to the much easier to use tensioners fitted to the 6 cylinder engines (from M50 onwards).

In other words, perhaps it is possible to go from this:
http://www.bimmernut.com/forum/attachment.php?attachmentid=8502&stc=1

... to this:
http://www.bimmernut.com/forum/attachment.php?attachmentid=8501&stc=1

To do it would mean replacing the multi-piece M60 piston-type tensioner assy with the one from the '98 onwards M62 radial spring-type tensioner, fitted to the later E31/E38/E39 (540i/740i/840i) 4.4 V8s. Are the mount points any different? Perhaps not! Maybe there's some different mounting hardware? Even if the pulley diameters need to change or the main belt has to be a little different in length, I don't mind. I know one thing, the new tensioner style makes it much easier to change the belts next time.

Now the ETK diagrams are not clear enough to make this obvious, so I did some youtubin' to get a closer look at the later M62 setup:

This video shows the mounting points on the later M62 show at around @5:50:
https://www.youtube.com/watch?v=6_kUGwtVvuY (thanks bavauto)

and this one shows the older M60 tensioner/pulley design @0.05:
https://www.youtube.com/watch?v=lxzwUnbcW5E

The mounting bolts (2x 10mm) sure look the same! Heh, the later design even has less moving parts and maybe even lower noise.

What do you guys think? I've not heard of anyone trying this before, but if it can be done, the later design is probably better and cheaper to replace too.


Looking deeper, there seem to be three setups for the V8 motors. Here are a few pictures of the different assemblies in their full, glorious, anger:
7
M60 tensioner partial assy: #11281736724, uses a 70 and an 80mm pulley (80mm pulley not shown)
http://www.bimmernut.com/forum/attachment.php?attachmentid=8500&stc=1

1993-1996 E32 BMW 740i 740il
1993-1996 E34 BMW 540i
1993-1998 E31 BMW 840i 840ci


M62 full tensioner assy: #11287515865, looks like 2x70mm pulleys
http://www.bimmernut.com/forum/attachment.php?attachmentid=8495&stc=1
1999-2001 E38 BMW 740i 740il
1999-2003 E39 BMW 540i
2000-2003 E53 BMW X5 4.4i X5 4.6is


This one looks different again, #11281742858
http://www.bimmernut.com/forum/attachment.php?attachmentid=8498&stc=1
4/1997-1998 E38 BMW 740i 740il
1998 E39 BMW 540i


M62 (late): #11281742859
http://www.bimmernut.com/forum/attachment.php?attachmentid=8497&stc=1
1998-2003 E39 BMW 540i
1998-2001 E38 BMW 740i 740il
1998-1999 E31 BMW 840i 840cii


S62, rated for higher rpms or different in some other way? They look like 2x70mm like the older M62:
http://www.bimmernut.com/forum/attachment.php?attachmentid=8496&stc=1
All V8 E39 BMW M5


Just for fun: For the N62N #11287545296

http://www.bimmernut.com/forum/attachment.php?attachmentid=8499&stc=1

2007-2010 E70 BMW X5 4.8i X5 xDrive48i

Whadayallreckon? Is the later setup better? The parts look to be pretty similarly priced.

[bennyg]

I think the tensioner on mine (93 540i) is gone. Steering transiently locking up under heavy acceleration, worse on a left hand turn, I reckon is due to belt slip. Will see if that's fixed when I get it back next week

[genphreak]

I think the tensioner on mine (93 540i) is gone. Steering transiently locking up under heavy acceleration, worse on a left hand turn, I reckon is due to belt slip. Will see if that's fixed when I get it back next weekThe tensioners aren't cheap either. I used to get the problem on the E28 535i (same setup as the e34). It was a worn power steering pump, though they had a slipper v-belt rather than the more tractable, constantly tensioned serpentine that everything after them had.

I don't know that the tensioner actually stops keeping tension so much when they fail- they might just stop absorbing lash after large RPM changes and lead more to noise, wear and belt failure.

Can't say for sure though, I've never seen one that is obviously rooted once removed.

Just had a look- Gates have a great explanatory pdf (http://www.gates.com/~/media/education%20RETIRED%2005152015/Files/Belt%20Tensioners%20Crucial%20Role.pdf) with a few nuggets in it, like this:

Damper malfunction should not be confused with loss of spring tension. Just like the Original Equipment (OE), Gates DriveAlign tensioners have a damper built inside the case which acts like a brake on the arm. Its sole job is to dampen the pulsation of the engine on the ABDS as the cylinders fire. Once it has lost its dampening ability, the arm begins to oscillate more resulting in increased loads on the bearings of adjacent accessories. Essentially, a failed damper creates a situation where the tensioner and belt will start to “hammer” the accessory next to it. Slight arm movement of the tensioner is normal as accessories turn on and off. However, chattering or excessive tensioner arm oscillation is a warning sign indicating possible damper failure; thus, the tensioner needs immediate replacement.

So clearly if you hear the belt squeal, or see any chatter in the tensioner arm (or the idler rollers) when rpms change or accessories load the belt, its worth checking out the tensioner, belt, idler arm bearing (and idler pulleys) for the cause. If not, the bearings around them may suffer from the transferred heat and shocks.