The 4matic engine mounts look different. Lets hope the engine mounts are still good since replacing them is a project. Thats why I say just inspect them for any leaking fluid. Other than the engine jumping around I dont know how else to check them, especially since they have a metal shield over them.

Heres my passenger side without the cover on it. I was checking just to make sure the bolts were on tight. Space is so limited om mine id probably have to remove the exhaust manifold to get to the mount.

 

I just went back to the 1st post where OP clearly stated "4Matic"

Sorry! And yes, even on rwd it's a project. I dropped the front portion of the exhaust, jacked the engine up a few inches, and removed my alternator. Still, the headers make it 100% impossible to actually remove the bolt fully. I won't admit how long it took just turning those bolts....1/32 of a turn at a time. Not one video I saw could've prepared me for that.

I spoke with an indy shop owner who's wife has a W212 E350 and he said every time they do those mounts on 212's or 204's, they drop the front subframe, support the engine from above, and remove the bracket from the engine block which the mounts are on. This avoids touching the headers and is seemingly the only way to get those top bolts all the way out. Fun.

It is hard to see under there to inspect. On rwd you can kind of tell even with the heat shield when they're sitting a little low, but certainly not a definitive inspection.

 

I swapped out my belt with a genuine part, tensioner with Febi Bilstein, and both idler pulleys with INA parts. The vibrations at idle are significantly improved, the belt is super smooth now, no vibrations or jumping when shifting. However, definitely still some vibrations when shifting into drive remain. It’s no where near as bad, and is definitely tolerable but I’m a perfectionist so I will keep pursuing other ideas.

One thing I’ve noticed is that the vibration is especially bad when first shifted, and the RPM’s dance around from very low (450ish) to right around 800 before settling at around 550-600 and being pretty smooth. I think another round of fuel cleaner and maybe cleaning the throttle body should help with the idling problem, I will try that later tonight and update as well.

 

Nastiest one I’ve ever seen. The front was a similar story, but I’ve never seen it be just as caked up on the rear as the front of the throttle body before. In the process of cleaning it right now, and PCV system overhaul is definitely next on the list.

 

So I just completed the 20 mile trip to the parts store and back for some more fuel cleaner. As expected, the car ran like complete **** (barely even ran at that) after cleaning the throttle body for the first 30 seconds. It hovered right around 300 RPM for essentially that whole time, minus when I gave it a little gas to try to help kickstart it. Once started, immediate improvement. I thought to myself great, this fuel cleaner should really help even the score even more. And I just put it in the tank so we will see how much it helps. I have an 800 mile round trip this coming weekend actually, so you all will definitely be getting an update soon.

As of right now, the vibrations are severely dampened, as I suspect the pulley system and gunk’d up throttle body were the worst of it. It feels a lot like it felt like when I drove my 5.3 GMC truck at idle. It’s not a Mercedes feel right now due to the vibrations, but it does feel like what you’d expect in a luxury V8 truck.

I have high hopes that the vibrations will continue to dampen, as I’ve noticed that the more I drive the better it gets so far. I will update you all this weekend.

Heres hoping I can avoid the tedious repair of motor mounts on a 4Matic!

Edit:
Figured I would write this down here, as both a reminder to myself and also for everyone’s knowledge who hopefully this thread helps someday.

If it doesn’t continue to improve and essentially disappear, my next step is to change the engine air filters and spark plugs and coils with genuine parts. I was told that the plugs and coils were literally just done when I bought it, but I’m so serious when I say that it seems like the only vibrations are coming from one bank of the engine. I have the filters on the way now, and plugs and coils will be next if that fails and the vibrations don’t continue to die.

 

Glad the belt system refresh was effective. It was angry indeed! That certainly is a throttle body that has not seen clean days in some time. I imagine the elbow for the MAF to throttle body has a fair amount of residue as well? Try giving the MAF a quick clean if you haven't already. The residue or lack thereof in the MAF elbow will tell you a little tale about the pcv condition. Some oil will be in the hose that connects the MAF elbow to the centrifuge cover (back of bank 1 exhaust cam), but it shouldn't be excessive.

I hope your intake manifold is not too compromised internally. The evidence found on the throttle plate could be a mirror to the inside of the manifold. An easy enough job, but expensive one. It doesn't seem like this is a focus now anyway, as your symptoms are most noticeable during stationary shifts rather than red light or traffic idles.

Funny you mention the symptoms feeling as if they're exclusive to one side. I always feel like bank 1 is more of a "problem child", most notably in the differences between bank 1 and bank 2 spark plug wear and how much more severe the symptoms of my failed valve cover sealant was on bank 1 when I 1st got the car. For what it's worth, every single mention I've ever heard of the infamous M272 piston slap idle noise is ALWAYS localized to bank 1.

 

I did clean the MAF while I was in there as well, but it actually seemed to be in good shape which surprised me. There wasn’t any visible residue at all, but I cleaned it nonetheless. Also surprisingly, the elbow connector was pretty much clear as well.

I share your concern for the intake manifold as well, and that’s a big reason I opted for another round of fuel cleaner to see if maybe my intake valves are just caked in carbon deposits and/or oil and causing the vibrations. I agree it’s an easy job as well but I would definitely prefer to avoid it all together. I have some Intake Valve Deposit cleaner by CRC still laying around from when I used to have a direction injection vehicle, I wonder if it’s okay to use on a vehicle like this that’s port injection. I’ll have to do some research and see if it’s worth my time to try to clean the intake manifold with it.

And there are definitely vibrations at idle at red lights and the works. It’s not as bad now, but it definitely was always at its worst when I first shift after a cold start. Every day the RPM’s would drop super low for even a warm engine, and then shoot back up and cause some jerking but no codes shown or stored. I haven’t had a chance to see if this has gone away yet, but the vibrations while stopped at lights has decreased significantly.

And I’m not sure which bank number the driver’s side is on this engine, but I assume they stick to tradition in that driver’s side (in the US) is bank 1. That’s definitely where my issue lies. One of these days I’m going to pull the spark plugs out and see if they really were changed. And whether or not quality parts were used. If they’re some cheap knockoffs, I’ll bite the bullet and spend the $570 on the genuine coils and spark plugs kit on FCP.

 

Bank 1 is the passenger side. Good to know when dealing with O2 sensor faults.




I think you are in the right direction using the fuel cleaners like Techron. I wouldnt over do it. I recently used two bottles of Techron then just used some Seafoam since I got a new can for my small engine gas containers. 1oz/gallon is what I use for both products. My engine seems to be running perfectly right now, previously is seemed a little rough. Now i wont use an additive until I think its running a little rough again.

 

Good and bad news.

The bad news is the vibrations aren’t completely gone and I don’t believe they will go away completely on their own.

The good news is the vibrations while idling have died down so much after two rounds of fuel cleaner (and the long drive) and the belt system overhaul, that it’s very tolerable and basically isn’t even noticeable when stopped. Small vibrations, but still there.

Some more good news is that now that those have finally calmed down, I can tell for sure that one of the mounts is dead, and I believe it’s the transmission mount due to the fact that my motor is still as a board when I shift gears, accelerate, etc. I had a friend record for me while I did the above and there’s absolutely zero movement visible.

I believe replacing the transmission mount will completely remove my rough vibrations, and I will be ordering from the original manufacturer, Lemforder, for a replacement shortly.

Other than that, the car made the 400 mile one way trip beautifully. Very comfortable ride, minus some vibrations I noticed when I’m lightly on the gas and the car is on the verge of shifting (again leads me towards transmission mount).

I love this car and don’t regret the purchase. Current list of things to do, in order, is transmission mount, pcv overhaul, plugs and coils. Better to be safe than sorry with those last two, but I do believe the transmission mount will remove the last remnants of the vibrations. I could probably hold off on it for a few years honestly, but like I said before, I’m a perfectionist when it comes to this stuff lol.

I will update if anything has changed after my drive back on Christmas Eve, but I doubt it will get any better without replacing the mount. I will definitely update once I get that swapped in, though it will admittedly probably be a few weeks by the time I get the chance to.

Thank you everyone for following along so far and Merry Christmas.

 

I found a photo i took when I was inspecting the pcv sytem. inside of the throttle body looked ok, some oil residue on the outside. I disconnected the tube connected above the tb and used compressed air from a can to blow it out from where it connects at the purge vavle. Nothing really came out so it was clear.




Im not sure how to even inspect the 4matic trans mount. Guess a floor jack can be placed under the pan and raised, see if it lifts up any indicating the mount has settled down. Seems pretty straight forward to replace. I'm sure this will be on my list at some point. The weather is getting cold so no more maintenance for me until spring, hopefully.

 

Those torque specs are greatly appreciated. It’s getting cold up here as well, when I left southern-bound this morning the wind chill was -15F lol. I would love to wait until spring, but given that I just got this car it seems better to get it done now rather than later.

Also for your own general knowledge, there was a great post about changing it on the 4Matic on this forum I managed to find. Heres the link:

https://mbworld.org/forums/c-class-w204/822609-2010-c300-4matic-transmission-mount-diy.html

 

I was near a napa so stopped in to get some more Techron since its on sale still. I was looking through my photos I took when messing with the pcv system and surprised how clean the throttle body looks inside. Wonder why yours was dirty, looks like old varnished gas. That may cause idle issues.

 

Transmission mount arrives tomorrow, I will be swapping it over this week, either tomorrow or after the new year.

On another update I discovered while checking the car over today, please read a new thread I started on a new problem. I found the spark plugs to be way out of spec, and I only hadn’t considered them up until this point because I was told they were new. Please advise if any of you happen to know the answer, I’ll link it here:

https://mbworld.org/forums/c-class-w...ml#post9088096

 

They would have been the first things I checked when looking for a vibration.

 

Me too honestly, but I was told they had just been changed by the dudes mechanic so they were always in the back of my mind, but not the first failure point I thought of checking. I mentioned in previous posts I wanted to go and check those anyways to be safe after the mount, and I’m definitely happy I did now.

 

Attached are photos of the new and old mount.

Question for you all though. Is that oil hydraulic fluid from the worn out mount, like what happens with the engine mount? Or do I have a transfer case leak?

Edit: After some research it seems to me that the transfer case and transmission share the same fluid? If this is correct, then that must be hydraulic fluid because it acts much more like a motor oil than a transmission fluid.

 

Just got back from the test drive. The vibrations I felt when lightly on the throttle have greatly disappeared. It happens about 20% as often as it used to, and when it does it is far less violent. The vibration at idle has no noticeable difference, besides no jerking sound when I begin to accelerate from a stop anymore.

I truly do think that changing the plugs and coils should eliminate the rest, and if not the only thing I have left to do is change the motor mounts anyway, and if that’s the case I’ll put it off until it’s warmer. That’s supposed to get here tomorrow so I will update then.

 

It's such a great feeling when a simple mount replacement does exactly what you hope it will. I can only speak for RWD, but I certainly noticed more of a positive difference in doing the trans mount than I did with new motor mounts but my trans mount was far worse off. V8's are naturally more rough on the motor mounts than what we have. Did you notice any weeping around the seals for your cv axles or trans output shaft?

I did have occasional rough idles from my intake manifold just before it failed including a few rough cold starts. I noticed the famous broken lever a day before I got codes for tumble flap position errors. I can only confirm this because I got that "hunch" from seemingly nowhere, roughness ensued, manifold swapped, smoothness returned. I only bring this up to reference a few posts ago. Hopefully that's not at all on the radar. I did my pcv stuff when 1st getting the car in hopes of not dealing with the manifold. At least I had close to 4 years before it failed. For what it's worth, my valves looked beautiful when I had the manifold off and at that point I had never used Techron or the like.

How's your fuel economy and fuel trims? My tired plugs were robbing me of enough mpg's to notice and I was down on power more so than harsh vibrations, but that is of course a classic bad plug attribute.

 

I haven’t checked fuel trims, and manifold isn’t off the table but I believe it’s okay. I stuck a borescope in there when I was cleaning the TB and it looked okay.

My fuel economy is definitely lower than I would’ve liked, but I never second guessed it because I only just got the car. I get around 18mpg in the city, but got 29mpg on my long trip last weekend (mostly highway). I am excited to see what happens with these new plugs. I live in the mountains so I usually get the highway rated mpg easily just driving around town with every car I’ve owned previously.

And I didn’t dive in too deep because I started as the sun was setting so I was in a rush lol. But the driveshaft output seal (towards the rear axle) was dry as a bone. I sprayed it down with brake cleaner so I will check again in a few days.

Edit: Forgot to respond to one other thing you said. I need some small miscellaneous parts, so I ordered from MB and included in that order is a new PCV system (drip pan, cover, and hose to throttle body). I did remove the hose yesterday as well when I checked the plugs, and definitely had some liquid oil in there so I ordered it right away.

I also ordered a new oil cooler gasket, as I noticed a small bit of seepage from the bottom of the cooler. My current plan is to change the gasket at the same time I change my oil in roughly another month. I want to change the coolant and power steering fluid as well, and since the coolant needs to be drained and the power steering reservoir needs to be emptied and moved out of the way, I figure I may as well just change the gasket and all 3 fluids at the same time.

 

You saw 29mpg? That is great. I have never seen mine go over 27mpg.

here is my transmission:





I had noticed my tranmision looked all wet with fluid so i sprayed degreaser and hosed it down. Inspected it awhile later and didnt see any active leaks. I searched around and it seems sweating is normal. if there are drops of fluid then its bad. https://charm.li/Mercedes%20Benz/200...ansfer%20Case/



Example photo they show:

 

It definitely had more oil than that, but it has 178k miles and who knows when the last time it was degreased was. I didn’t make it perfect by any means, but I did spray a generous amount of brake clean and wiped it with a rag, so I will check again in a few days for any more seepage or obvious leaks. It drives perfect, so I believe it may have just been a buildup over time of that.

And yes, I was pretty happy with 29mpg, but like I said I’m up in the mountains so it’s a lot of coasting. One time I got just shy 43mpg in my 2.0 Ecoboost fusion on a 400 mile round trip. For those who don’t know, that’s rated for 31mpg highway.

I suspect that after changing the plugs and coils, my fuel economy will be even better and I’m definitely excited for that. As great as the highway fuel economy was that one specific time, for most other trips I get around 22mpg which is definitely lower than I thought I would be getting, which now it makes more sense to me.

Also that’s a very helpful WIS you got there. If you don’t mind me asking, where do you get all these? I see you post all over these forums with some very useful knowledge and WIS sheets so I would love to be able to find them myself.

 

Here: https://charm.li/Mercedes%20Benz/2008/

 

I just wrapped up a 3 hour project. I had a lot of parts come in today, so I knocked it out all at once. Everything you see pictured was installed, except the wiper blades (for when I get new windshield), oil cooler gasket, and centrifuge hose. Mostly all genuine, minus the obviously labeled OE boxes.

In conclusion, spark plugs and coils helped a LOT, and I also changed the oil drip pan and centrifuge cover. I did not change the hose that you can see pictured because there was a pinch clamp holding it to the elbow to the throttle body, so I’m going to get a regular hose clamp in a few days and then swap over the fresh hose, but that’s a minor thing anyway.

The vibrations when first starting the car and shifting into drive haven’t gone away, but they have improved and my RPM needle is steady as a bullet now. No more jumping around, it’s just a vibration and a small jolt in the drivetrain. I did not take it for a long drive, only around the block, but after the initial switch to drive, things seem to be even smoother now and no more vibrations when stopped and on the brake (again, only a short drive but it didn’t happen once).

Now that I have corrected all other symptoms, and thankfully all of them needed to be done, the only conclusion I have left to 100% solve is to replace the motor mounts. They visually are fine, but they’re the only thing that I can think of that’s left to replace.

I will be putting that off for a little while, as unfortunately I need a new windshield as a rock cracked it the other day. But one of these weeks soon I am going to purchase two engine mounts and swap them over when I have a few days in a row off. It will be a total pain but I will switch them and that should solve everything.

If anyone knows the OE manufacturer for the engine mounts, that would be very helpful, but otherwise this is the final update until I make the swap. Thank you all for following along!




Edit: I actually had an idea. Tomorrow afternoon, I’m going to jack the engine up a little bit and then shift it into drive to see if that eliminates my vibrations. I’ve been brainstorming the best way to actually diag the engine mounts before just throwing money at it, and I believe this is the best way to. My theory is that by lifting the engine up and taking the weight off the mounts, if the vibrations go away then I know at least one of the mounts is flattened, and if not then I’ll know to look elsewhere.

So scratch the whole “last update for now” thing, I’ll be back tomorrow lol

 

Lifted the engine up this afternoon, started the car and shifted into drive, and absolutely no vibrations! Engine mounts are the next and last thing on the list now, I hope this thread helps someone someday. I’ll attach some photos of my setup and where/how I jacked the engine up to test.

 

Sounds like you're making good progress! As Tim said, 29mpg is a milestone in these cars. BMW seems to crush MB when it comes to fuel economy. People with built N54's with twice our HP seem to get the same if not better mpg than us with stock M272's. I could only manage 29 mpg with roughly an hr of straight, consistent, totally uninterrupted highway driving at 70mph give or take and also 18ish around town (plus or minus 2 mpg).

Hopefully you don't have anything to worry about as far as transfer case leaks either. Surprisingly, the hose clamp you mentioned for the hose connecting MAF elbow to centrifuge cover is reusable. It's quite beefy. I used a pick tool to gently undo it and it clamped nicely back together with a hose clamp tool for those Euro style clamps.

I hope you make out good with the oil cooler gasket. I feel like I'm 1 of 2 people who had the entire assembly fail. I could never get comprehensive info on this, but apparently there's a check valve that can (does) fail which allows oil to get into the cooling system. I had 2 gaskets fail (each lasting about a yr to a yr & 1/2). The 2nd time, I did the cooler and entire oil filter housing gasket. No dice. An MB master tech and former dealership foreman told me it happens & to also swap out the coolant reservoir due to the impossibility of appropriately cleaning it out. There is a revised part number for the entire assembly. I only bring this up because I've only seen it mentioned in passing twice in my near 5 years of owning this car which I don't understand. Even if an isolated issue, it should still be known.

Good technique on checking the motor mounts also! The usual method I see mentioned for many MB's seems a bit rough to me, as these cars (at least mine and my sister's W203) don't seem to like it much at all. The word is to hold down the brakes firmly and blip the throttle to perhaps 2kish and watch the the engine to lunge. It will a little even with fresh mounts, but is very violent with worn ones. I think I like your method better. These aren't late 60's Mopars hahaha. They're not weak cars, but I don't think they like being roughed around. Maybe it's just me.