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The link regarding the OM651 chain is cross linked to the "other forum" which has much to say on the OM651 chain failure modes (guides too apparently) which is quite recent. But I don't like linking directly to the other forum as it doesn't seem right to do so.

I think you are right, when it comes to sub 2l engines. I also note that the cam chain is sensibly on the front of the engine, making it much much easier to change.

The OM626 appears to have a timing chain rather than a belt. I do like the fact that it can be changed very quickly though. https://m.youtube.com/watch?v=Axkc2dTZ1nY

Actually there seems to be a big problem with the OM651 after 100,000 miles. http://www.mbclub.co.uk/forums/engine/170639-high-mileage-problem-om651-diesel.html It looks like lots of independents are reporting this issue across all the forums. It's very apparent that moving to a simplex timing...

Pity they didn't move back to a duplex chain with the OM654, then it wouldn't have been an issue at all. Also it looks like access for the OM654 is much worse than the OM651. Particularly the chain tensioner. It seems to me that bolting the turbo and cat to the engine unit is more for economy...

The engine appears to be very difficult to maintain in that in order to access certain parts of the engine you'll need to remove the cat, turbo and a load of other items. The cam chain tensioner appears to be particularly difficult to access. It's almost as if the engine was designed as a...

Does anyone have any info regarding the new 2.0 OM654 engine yet? I'm particularly interested in what's been done to address the OM651 simplex timing chain issue. Experience has shown that the OM651 requires a timing chain replacement at around 80-100,000 miles, which is really difficult due...

Yes there's definitely a business model change going on in the European car industry. Most makes now seem to have a built-in life of around 100,000 miles before it starts getting too expensive to justify keeping the car. Additionally I've noticed that car makers (including Mercedes) no...

Thanks, I've also done a fair bit of checking about the M271 timing chains since my original post. It seems that the inverted chain is no better than the original roller chain regarding lifespan, with 100,000 miles being the normal life. Since changing the the tensioner is a £2000+ job, and at...

My 270CDI did this as well. Turned out to be the MAF sensor. I had another symptom as well, if you tried to accelerate too hard whilst the engine was cold it would drop into limp home mode. Stopping and turning the engine on and off reset it, with no engine code being recorded. Changing the MAF...

I had this one after having my torque converter rebuilt. The suggestion was that worn bits of old converter friction plate were getting through to the converter and putting it off balance (I guess it had to go somewhere!). Anyway two gearbox fluid flushes and a month of wearing in the rebuilt...

I agree, the OM642 appears to be the last of the "designed to last" engines, with duplex timing chains etc..... My friends tell me that I'm bit of a dinosaur myself and that no one keeps a car 10-15yrs any more. In fact I'm told that the whole idea of saving up and then buying a car so that you...

Having read the reports I can't see any reason to think that the M274 engines are going to be any longer lasting than the M271 engines. Such a shame, but then again I guess Mercedes are designing them for a given expected life of around the 120,000 miles that most of these low end cars actually...

Yes I tend to agree. These engines don't look like they are going to be capable of the 200,000+ miles the old OM647 in my W211 can make. I think I'll end up with the OM642 diesel V6 instead. I had hoped to get a modern petrol rather than an old tech diesel, but at least I'll know that it can...

Interesting, but I note that the M271 and M271 EVO call for the same spec oil even though they use a totally different type of timing chain. This suggests that the oil is speced for the bearings rather than the chain. I also noted that although inverted tooth chains are stronger, they are...

Thanks for the info. I'm looking to move from a W211 270CDI, which I've had for 13yrs and 180,000 reliable miles, to a petrol and am concerned about engine longevity. I wouldn't have considered the earlier M271 but am looking at an E coupe with an M274 to again keep for 10-15yrs. Simplex...

Thanks for that. It seems also that the later versions of the M271 also have an Inverted Tooth chain. (the M271 EVO specifically). All the reports I see about M271 chains appear to show the old roller chains, so I wonder if using Inverted Tooth chains has stopped the chain stretching and...

EVO variants Does anyone know if the EVO versions of the M271 with the inverted tooth timing chain still suffer from chain stretching, or has the change cured the problem?

Timing chain They certainly mention that timing chain losses have been reduced, but noticeably fail to say if the design of the chain has been changed from a roller bearing chain to a different design. Maybe they didn't want to draw attention to the failures of the previous M271 simplex timing...

Hi, I'm trying to establish what changes were made when the M271 was superseded by the M274. I know the M274 still has a simplex timing chain, but I understand that it was changed from a roller type to another type to stop the stretching problems? I'm I correct in this, and did it work?