jgrumby

Hello everyone,

I'm the proud new owner of a 2010 R350 4Matic (gas) with about 102,000 miles on it. Love how the car drives and that MB touch.

I have noticed an oil smell from the engine compartment, and doing some research suggests that it is likely the cam plugs and/or centrifugal oil separator at the back of the engine.

The repair itself on the M272 engine seems straightforward, and I am comfortable doing the repair, but the engine on the R350 seems to be buried much father back towards the firewall than almost all other models that have the M272 engine. I am aware that the metal shroud that covers the back half of the engine is to be removed for the repair, but still, from the videos I can find, the back of the engine remains very difficult to access, which is needed for this repair.

I've done a lot of searching, both on this forum and the web as a whole, and I have not been able to find any videos, images, or discussion about doing this specifically on an R350 (some MB variants have the entire top of the engine exposed, for example, which makes the process very straightforward). I have watched (with envy) the actual replacement of the plugs and oil separator on such engines, but worry that this job on an R350 might be a whole different level of difficulty.

So, with that said, I would welcome any thoughts and suggestions from folks that might have taken on this repair (or tried and threw in the towel). All thoughts and comments would be most welcome. We are snow-bound for the moment here in the Northeast, and I don't have a garage, so I will have to wait until the weather warms to tear into the car. Although not a professional mechanical by any stretch, I have several decades of working on my own vehicles and don't mind purchasing any specialty tools that might be needed.

In the meantime, if it turns out that the procedure for an R350 is nowhere to be found, I'll document the process myself and post my trials and tribulations, if it would be useful to the group.

Thanks again everyone in advance for any thoughts and advice. I've found the discussions on this forum to be very useful.

Jonas G.

jgrumby

Hi Everyone,

Since my last post, I found a video here:


It's not an R350, but the engine is similarly tucked back into the firewall, and they provide a lot of detail in replacing the plugs and oil separator. The job looks a bit frustrating but not impossible.

I will continue to update this thread if I find anything else relevant, and will post my own experiences, good or bad, once I get the chance to get under the hood (might be a few weeks with the weather here).

Thanks all,

-Jonas

jgrumby

OK, finally got warm enough to have a look at this. Turns out the centrifuge housing (cent) had oil all around it, so decided to change it. The three plastic plugs were dry as a saltine, so I left them as-is.

The cent replacement was not as difficult as I had expected, even on the R350 with the engine half buried into the firewall.

1. First need to remove (1) two air inlet tubes, (2) engine cover/air cleaner/hose (2 parts+hose), and (3) the metal shield across the rear portion of the engine compartment.
2. I used a 3/8" flexible long-handed ratchet and an E10 socket from Harbor Freight (it was a little shorter than a Blue Point I had, and the torque requirement is very low). Use as thin a socket wrench that you have
3. Remove cent connecting hose by hand (wiggle/walk off)
4. Remove 4 Torx screws on cent body. They are at roughly 12:00, 3:00, 6:00 and 9:00.
   1. one on top is easy
   2. one at bottom and one underneath connection tube have space for wrench, but have to be done by feel, since you can't see. Not as hard as it sounds.
   3. one opposite tube connector is easy to get to, but distance to firewall is tight. The socket and ratchet just barely fit over the screws.
   4. all screws very easy to turn upon breaking free. Can easily remove with fingers even in cramped confines.
5. Remove (by hand!) the old centrifuge. There are two locator pins about 3-4 mm high that the part must clear by first pulling away from the engine
6. Wipe mating surface on engine with clean rag and cleaning solvent of your choice. I used CRC Brakleen, went around three times with a clean rag each until there was no significant residue
7. Oil interior sealing disk and entire o-ring around periphery of new cent housing. I also oiled the two holes for the locating pins but this probably not necessary, and may give a little resistive pistoning if the oil seals the air in the back of the pin hole.
8. Put new cent in position and pull towards front of engine. Part quickly seated against engine surface with a satisfying "snap". Tighten screws alternately by hand, then snug up with the socket wrench. I did not use a torque wrench (actually I think the tightening spec is 6 Nm, then turn an additional 1/4 turn. Weird. No hope of me getting a torque wrench back there, so I didn't even try. I tried to make a mental note of how much force it took to break the bolts free, then reproduce this on install. +1 to MB for using decent-quality bolts. There was no corrosion at all on any of them.
9. Reassemble in reverse order above, start and check out.
   1. I let the car idle for 20-25 minutes to check everything out
   2. Note that several drops of excess oil from Step 7 fell on manifold, and when the car was started, this started to burn off as it warmed up, which was unnerving, but after about 20 minutes idling, it dropped a lot.
   3. I then took it for a test drive, and got another big whiff of oil after the first stop light or two. I figure the engine exhaust heated after working the engine harder and other parts with oil heated up and burned it off.
   4. After another 10 minutes of driving, there was no smell at all.

Took about 1.5 hours, and I went very slow, just to get a lay of the land, since this was the first time I had done any work on the engine.

I have a few pics if anyone is interested. Not terribly helpful, but may at least provide a frame of reference.

Best,

-Jonas