Not the greatest at searches but looking for how to on measuring engine mounts. The tech said there is a 2 mm variance and thats it. Where do I measure from and should I use a dial caliper? I have the WIS but I don't see any info on this. Also the book way of doing mounts is a bit different from videos and other posts using a floor jack or crane. I have '11 c300 sport 4matic with vibrations that mb master tech said most likely mounts and to check them. Thanks all for your time.

 

You open your hood, put the car in drive, and slowly press on the gas while braking. If the engine has substantial movement, you need motor mounts. Only go with Febi or OEM genuine mounts. Do no go for the Chinese 1 year warranty garbage to save 100$, they will fail in 1.5 years.

 

yeah I told that to the master tech at mercedes and he gave a chuckle. That's how you check a solid mount. Hydraulic can appear fine but a 2 mm difference and they need replacement. I would like to know where the measurements are. If I can't then I'll go back to MB and get the info then relay it

 

What measurement are you on about? There's nothing to measure, if they are leaking or have excessive movement/vibration doing brake torquing, they need replacing. A lot of mounts are partially hydraulic, the way you diagnose them does not change.

 

I get u. I'm only telling you what the mb tech told me. I will call him and relay info. I'm thinking it's the bottom of the bell to the top of base.

 

I actually just did the motor mounts, transmission mount, wheel bearing on driver side, axles replaced (torn boots) and the bearing on the shaft that goes through the oil pan to the driver wheel hub. (107k miles on vehicle)

My mounts were not leaking, there was not excessive movement from the engine when in drive, brakes applied and gas applied.

I had a harsh vibration when in reverse or drive stopped with brakes applied. It was basically quiet when driving. I also had a set of motor mounts out of another 4matic that were used and they were not leaking either despite having 193k miles but were bad also.

When I compared both of the used motor mounts with the new one it was so incredibly obvious that they had been compressed 1/4 or more than the new ones I got from fcp euro.

I dont think you can measure your mounts in the car unless you know how far away the heat shields are supposed to be from the frame rail or some other measurement, just guessing but maybe crank pulley from sub frame. My car probably had the issue for a while (I got it at 107k miles) since the vibration was so harsh so I would guess these cars mounts start to go around 80-90k depending on how you drive.

I had to unbolt (not remove) the alternator to get the pass side mount out, the heat shield on that side is one of the hardest parts about the job. I had to reach around the back of the exhaust manifold with a ratchet and extension and guide the etorx socket to the bolt. It was at the end of my reach and a real pain. Driver side I had to remove the axle and the shaft that goes through the oil pan to get the mount out once it was unbolted. The special tool for the 16mm bolt on the top of the motor mount is required and is also not the greatest design for the application but works ok, it would be better if it was shorter. Overall a real challenging repair but made a huge difference.

First pick is engine mount collapsed. Second is the rubber cover pulled up to represent what the new one looked like

 

I just ordered the tool. The guy in the video grind it down a 1/4 in so it fit in between mount and exhaust manifold. He took the alternator out.

 

For them to split and have excessive movement would have to be a complete failure which would result in hydraulic fluid leaking. I was surprised how good my mounts looked at 180k miles when I pulled them out. I did have slight vibrations here and there but nothing excessive, I would imagine that's how these mounts seem to fails and cause vibrations. Hopefully, the new mounts will get as much mileage since it's not a fun job, I was just lucky I had to take the engine out anyways which made it an easy "while you're in there" job.

 

Just curious but what did you have to fix that required the engine out? How has your 4matic fared over the years, has it needed major maintenance before the 180k work?

 

I purchased my 2008 c300 4maitc in 2013 for very cheap because it was neglected, mainly it needed transfer case bearings. The oil was low and black when I got it at 80k miles. It lasted 100k miles trouble-free until the engine gave out at 180k, Cylinder 7 piston ring gave out when i was pushing it one day. I installed a 3.5L engine from a 2012 GLK350 with very low miles that I sourced for cheap. This was a year ago this month and I require a lot of driving for my business so I'm already at 200k miles with the new engine and I'm impressed the transmission is still going strong being its all original other than the transfer case bearings. The valve body was cleaned at 140k and typical fluid changes every 40k.

 

Very cool details thank you for sharing. When you say the oil was low and black is that the engine oil or transmission oil? Mine with 107k miles seems to have no transfer case noise surprisingly, only noise is when turning (tested in a parking lot and that is when I can single out the noise from the road noise), I can hear what sounds like worn brake pads almost but I have just checked the front pads and there is a lot of pad material left.

Did you do all of the work yourself on the transfer case bearing? Do you know if the races were just worn or had pieces of the roller bearing fallen out? I have been interested in that issue lately and doing a bit of research on it. When I first read about the issue it seemed like a massive job that always needed the transmission replaced as well but after more reading it is seeming like a very fixable problem with fcp euro even offering a bearing kit which means lifetime warranty on the part. That is awesome to hear the bearing and transmission are holding up so well. I have gone from thinking the 4matics were not something I would recommend to a friend but now it seems like it is a manageable system with cost effective solutions.

Also on the 40k fluid change which ones are you referring to? I would like to check my transmission fluid to see the color/condition but need to look up exactly how that is done.

 

Changing the transmission fluid on these cars is key. If you do not know the history and are over 70k, change the fluid. These transmissions have a lot of clutches which leave a lot of material as they wear. The electronics get covered with the clutch material and short out electronics. Having clean fluid is key for longevity.

 

If you think your mounts are bad, they are, change them. Super common failure. Don't even bother trying to measure them, they are collapsed enough to see, they are bad.