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Hey guys I've got a Mercedes S550 2012 model with rear wheel drive only with the new m278 twin turbo engine. I want to attempt to replace the engine mounts and I have read that you have to drop the subframe to get access to it but was wondering if anyone on here has ever pulled it off by doing it, in situ, without dropping the subframe? I have heard that it is possible by removing the engine mount bracket along with the engine mount and then switching them out but that it is extremely extremely tedious and difficult. Just wondering if anyone here has truly done this job at the DIY without dropping the subframe? I did my old 2008 S550 three times over the life that I owned the car.... that one was very, very easy different engine no turbos.
I just had my engine mounts replaced a week ago by a very competent independent mechanic. Glad I found him. He said Mercedes say this job takes 11.5 hours because the sub frame has to be dropped. Whether he actually did or found another way I don't know. I purchased the special wrench that is supposed to give top access to the mount stud but the mechanic told me its no help on the m278.
This and the fairly simple transmission mount replacement has transformed and restored our 2013 S to silky smoothness. I was happy my mechanic mentioned the needed to torque the suspension bolts with the car's weight on on four wheels,
I had to replace my Starter a few Month back and for that i had to take part of the exhaust out. Had a good look at the mount on that side at that time and i am fairly certain i would be able to get it out that way...there was good clearance....I assume the other side would be the same. When i did that job on S55 i was able to lift the engine by about 3 inches and get them out the same way.
I hung around when I went back to have my mechanic, Eric replace the broken crankcase vet tube, so I was able to ask him about the mount install. His invoice showed 11.8 labor hours at $120/Hr or $1416 just for the motor mount install labor. I think this matches the Mercedes estimated hours. He said he followed the book procedure and did drop the sub frame to gain access. He also said he followed Mercedes protocol, when re-torquing sub frame components with the weight of car sitting normally on its four wheels.
The mount diagnosis came from Eric after I described the low speed vibrations and roughness I was feeling. Searching this website for "vibrations" lead me to 4-Matic axle shafts, which can't apply to our base or perhaps low power steering fluid causing steering vibration, or the transmission mount which which Eric said appeared fine but was replaced just as a precaution. The vibration was indeed caused by the failed hydraulic motor mounts. Eric showed me the hydraulic fluid covered leaking dirty old mounts. The difference in how the car drives is day and night. Silky smooth now.
Interestingly the replacement of the breather pipe didn't go off with out a hitch as the "Breather Pipe Plug" broke when Eric removed the old hose. No wonder FPC Euro sell the two items below as a kit. Of course I only had the "Breather Pipe".
No problem, it meant I got to drive Eric's F350 Super Duty Turbo Diesel to the Mercedes Dealer to pick up the plug.That was quite an experience in itself.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
