Whilst it's oil cooler seals for £1k on the E350, it's timing chain on the 2.1 OM651 diesel (E220/250).
Due to have car (w204 220 CDI) serviced at my (well respected) indie soon, conscious I'm now potentially entering higher risk mileage usage relating to potential OM651 timing chain issue. Effectively need to decide if I take "preventative insurance" route of having chain replaced. Like all...
forums.mbclub.co.uk
Useful reading for the OM651.
In summary, turn off stop/start at the beginning of every journey, as that is probably the cause of snapped or stretched timing chains on OM651 diesel engine.
If you hear unusual noises at start up, either squeeking or noisy tensioners or pulleys, or a slap slap or clack clack of a loose timing chain for 2-5 seconds, get it looked at. The thread suggests no rush; I'd say if you get the noise, get it looked at pretty much immediately.
Timing chain rattle will be most evident after oil changes.
Plenty with high miles (hundreds of K), but those must have been living at 60-70mph to get 400k on them by now, so no stop starts like in traffic and at junctions.
Just keep an ear out for the noise, and if you hear nothing (from outside the car or with the door/window open) don't worry about it.
They won't find it on service. It happens quite suddenly and you'll need to hear it and catch it, otherwise it will stretch or snap the chain. It probably won't happen, but better to know that on the very small off chance if you hear a noise only on start up, don't ignore it.
This vid is typical. He starts the car at 8 secs, you can hear the metallic rattle/slapping, and then at 12 secs it stops.
