Moto_Guzzi

At 135 000Km I decided yesterday to look at the pulleys with engine running, using a flashlight.

Saw that the belt wanders a bit only on the tentioner pulley, like about 2mm sideways off its centre.

I assume that this is indication of pulley on its way out.

Will release tention today and see if I can feel play.

Will welcome any comments regarding this, and if you would drive it further.

Today:
Ok, I locked the tentioner pulley with L&Key, removed belt and inpect pulleys.

I found the 2x slave pulleys as well as the tentioner pulley, not noisy, in fact they behaved like a new one was illustrated on Youtube compared to a faulty one. If spin by hand they dont run away with noise, they comes to a halt after few turns. They do not have play backwards and forward in line with the running of the belt.

What I am not sure about is each one of them has the same side wiggled play of like 1mm or less.
I will have to compare with new one to know.

Should they have zero side movement if twisted-?

Moto_Guzzi

Ok, I decided to remove the 4 parts for inspection, this is what I found:

1-The belt: The belt seems ok, no cracks, I'l keep it in boot as a spare, they probably replaced it before guarantee expired.

2-Idler pully with grooves=On it way being shot. It feels ok, but if I wiggle it next to my ear, I can hear a broken ball bearing, or a ball dry in its own place, it however does not run noisy freely away as illustrated on Youtube. This is the one which will have me stranded in a 500-1000Km trip.

3-Idler pulley larger with centre groove=This one seems solid and ok removed.
Keep as spare.

4-Tentioner pulley=Next to my ear I can hear this one is in its early stages of going bad.

Ordered 4 x parts will get tomorrow, replace all 4 of them. Relieved I caught this in time.
Spares say they use same bolts, no bolts with replacements.

Note-1:By inspecting the parts mounted, I probably would have taken a wrong calculated risk.
Note-2:Noted the waterpump has a minor play, no leaks=Will get this replaced by garage with thermostat and fluid drain/flush later this year.
Alternator=OK, was warned about this one.
Steering pump=OK
Airconditioner=OK


Note:3 Comparing the quality of the small idler pulley with groves & the tentioner pulley(only this pulley) against the larger idler pulley with one groove, the other two seems inferior quality in design, Mercedes could have done better with them on such an engine.

timlippold

How easy was the replacement process and how long did it take. I have this on my to do list. Thanks

Moto_Guzzi

Parts obtained:

1-Belt=A 003 993 72 96........Mercedes Benz......Made in Spain.

2-Tentioner assembly & pulley=A 272 200 02 70......Mercedes Original......Made in Turkey(Daimler AG).
Proper Mercedes box packed.
>Compared new to old=New and old one same wiggling play(small). New one 100% silent, old one I can hear something small is there.
Both turn the same way forward and backword. I think the old one would be good for some time, keep as spare.
>No bolts with new part.
>Pin with new part=5mm x 40mm.

3-Large Idler pulley=A 272 202 14 19......Mercedes Original.....Made in France(Daimler AG).
>Both feel exactly the same in every way, this is a good solid pulley.
>No bolt with new part.

4-Small Idler pulley with groves(Guide Pulley)=A 272 202 00 00.....Engraved A 272 202 00 00...No country reference.
>Ok, my old one is bust one or other way, new one silent 100%.
> Came with bolt, bolt & washer not removeble by hand...?
>No box from Mercedes, came in plastic bag with label.

Note:
>>I noticed that on this one the ribbed side is the engine side, now it came with a new washer and bolt, however the black bushing
protuding with washer added has a clearance of 2.5mm, meaning if tighten to block the washer will roam free.
Keep in mind there is also a round protruding piece from the engine block over which the washer slip.
>>Comparing the new and old pulley again, the old one has not the protruding centre part, so I think I may
have a possible incorrect part here, although it looks at 1st glance the same.
>>>I will tighten the bolt to block and see with mirror what happens, maybe the centre part press in correctly.
>>>>This pulley is the weak spot in this Belt assembly train of pulleys in my opinion.

>>Will sort this out tomorrow with dealer........If neccessary.



Will do job tomorrow...............If small pulley is indeed the correct one

timlippold

Continental makes a kit.

Moto_Guzzi

Trying to obtain bolt torgue specs, have a clue but not 100% sure.
####??#####
Bolts easy to strip threads if torgued incorrectly due to thread type, I got this. This make sense.
I got mix messages from Internet searches, will have to climb on the phone.
##########

Bolts has some special resistive threading, no substances like locktite added, so I am not going to add either.
They remove with resistance, so I am sure they wont want to come loose just like that.

1-Belt Tightning Assembly:
2 x E12= 39/29mm x 8mm

2-Guide Pilley (Large) : (With 6mm shoulder)
1 x E14= 55/6/38mm x 8mm

3-Guide Pulley (Small):
1 x E12= 47/40mm (4mm insert black) x 8mm


###########
How long does this job take-?

For me it does not matter, 1st time I do it, as long as it does not fail on me.

If you know what you doing, got everything ready, it should be a 15-30min job.

I am sure you can rush it in 10 to 20 minutes.

Moto_Guzzi

Installation took 15 minutes.


Installed the Tentioner and 2x pulleys.

Tighten by hand with 20Cm-long small socket wrench.
>You find you cannot screw these bolts in by fingers due to resistance thread design.
>Noticed as you tighten these bolts it feels like hitting a wall suddenly at the end, maybe here one can break a bolt if overtighten, usually you feel some spring tightning bolts/nuts.

Install belt, make sure it sits good in slots.

Release tention, pull out pin, to tention belt.

Start engine, let idle no strange sounds etc, ok.

The torgue values I could get hold of varies between 20-25Nm & 35Nm. Too much difference to go on this.
As soon I have clarity about torgue values I will torgue the bolts, till then its tightened firmly by hand.

Moto_Guzzi

I took a 400Km trip today, and to my surprise noticed that the Temp guage stayed on 90 degrees, unlike the movements around it I noticed over the last few months, it behaved like always.
(25c outside).

I fail to understand that the replacing of the belt & pulleyes has anything to do with it, seeing I felt the belt tention before, and heard no screaches ever.

But thats good news in any case.

Note: Opened the small idler pulley, no ***** damamaged, but it was dry with no trace of lubricant left. It was manufactured in Turkey.

Colin G

Did you happen to find out the torque values for the pulley and tensioner bolts yet?

Moto_Guzzi

Although all bolts are 8mm thread, they seem to screw into different other engine parts mounted on the front of the engine and that then determines the torgue, thats why I am not yet sure about the torgue values per specific bolt/&/position of it.

I handtightened them according to own experience and is happy with that. You will have to ask a dealer for exact values per bolt/position.