In a 3/19/2000 post, Steve Brotherton talked about "petrified chain rails" being a predominant cause of chain failure in the
3.5/4.5, 3.8/5.0, 4.2/5.6 MB V8s

Looking through an IMPCO parts catalog, I see that M103 motors are equipped with what they call "Chain Rail Clamping Lever" and 2 "Chain Guides".

Everything wears out sooner or later; are the M103 motors susceptible to the problem that the V8s are? Thanks for your time.

Mike Murrell
'91 300-SEL

The statement I made was based on hundreds of repaired chain failures in V8s. The only other motor we have seen more than "ONE" failure are the 615/616/617 motors where we have seen maybe 20-30 over 25 years.

I have seen a couple 16v 190's fail and sold parts to someone doing a 103 motor that failed, but it is NOT a common occurance. We are currently doing no preventative measures on 102/103 motors. That might be reconsidered as the fleet gets over 200k. We advise upper chain rails (three only) on all the V8's at 75k intervals and chains at 150k.

All the motors that have no problems, use ratcheting chain tentioners. The problem with the rails is that they become brittle over time and there is no way to prevent the wimpy hydraulic tentioner (on V8s - no ratchet) from occationally loosing oil pressure after sitting (which rattles the chain hitting these rails which otherwise never contact the chain).

Yes there are plastic rails in most Benz motors, BUT they have different style chain tensoiners that don't allow chain SLAP! Of course on major overhaul they should be replaced. The M119 engines are going to be simular to M116/117 in failure due to simular tensioners. If you hear any rattle have it checked out!

To add. We don't see the 103's fail..I have yet to replace the chain in one.

I have seen over a hundred of the V-8's fail. (116)

I have seen more than a dozen of the 119's fail.

All was a result of BAD MAINTENANCE!!!!!!! And a customer who did not listen to their car.

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Benzmac:
Donnie Drummonds
300E
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM
OWNER OF MB AUTOWERKS .COM