E350 M272 Engine Vibration
 

Car: 2008 E350 4Matic Sport

When stopped in gear I can frequently feel vibrations. When I place my hand on the engine cover I can definitely feel it.

Observed Symptoms in past 6 to 12 months
* Cold starts can be sluggish -- by a second or two

* On occasion, on hot starts, after car has been idling then shut down and restarted a a few minutes later, the car will crank but not start on the first try but fires up solidly on the second. This happens only very infrequently (and actually sounds like a cam sensor issue).

Recent Work in Past 2 weeks:

* Engine mounts (today)
* New Spark Plugs
* New Engine Air Filters

Anyone else experience this?

depending on the VIN it could be a bad balance shaft.....
http://www.mercedesmedic.com/check-my-mercedes-benz-for-balance-shaft-issue-by-vin-m272273/

you can put your VIN into a link on that site and see. by midd 2008 i think they had fixed it but the early ones.....

Mine is an '08 so the balancer issue was resolved at that point.

if you say so....everything i read said it was into the 2008 model year.

No, I believe you.

I thought it was into the 2007 year -- which I learned here before I bought the car, and upon which my purchase decision was largely based. Regardless, my engine is in the safe zone, with serial 30 943712.

One huge thing I forgot to include were the new front axles -- done the same week as the engine mounts last July.

When they were initially installed, the car would vibrate badly but that gradually got better, to the point of not really noticing. Then the boot on the driver side began to tear so it was replaced under warranty this past March, so the vibration returned. They are likely contributing 70% of overall vibration when stopped in D or R. Car is relatively still and quiet in P or N.

What brand engine mounts did you use?

Lemforder

that's good it isn't that!
i was considering an e350 and was doing the same thing prior to deciding. ended up with an e500 instead

The E500 was actually my first choice. I would see one at my local supermarket regularly and loved the way it looked. But I could not find one during the time I was searching.

The happiest thing about the E350 is that it is easy to work on. (The only thing I could not do myself was the axle replacement.) It is even possible to do the control arm bushings while they are still on the car, which will be an upcoming project in cooler weather.

If it were me, I would still want to verify the timing. https://www.youcanic.com/guide/check-mercedes-benz-timing-chain-wear

Then probably replace the transmission mount.

Transmission mount keeps entering my mind, except it is only 11 months old and an MB part. I have a hard time imagining it could have failed, however, the engine mounts did and they were only a month older.

Some behaviors seem to support your opinion, such as when I come to hard stops and the engine and transmission shift forward due to inertia, and the vibrations are heaviest.

The vibrations started about three months ago and are not consistent. Sometimes they are here; sometimes they are not. They also seem to be temperature-related as they began with the start of 90-degree weather and yesterday, and the day before, when it was cooler (high 70's/low 80s) they were not as strong.

Because of that, on my list of suspects are also the ignition coils due to the occasionally slower starts and an occasional misfire -- but the latter has not happened since replacing my sparkplugs two weeks ago. But no codes, however, support faulty coils.

I wish I saw your post yesterday when I replaced my serpentine belt, so I could have done the timing check then.

I went ahead and ordered a new trans mount (genuine MB part).

I can think of no other explanation for the remaining strong vibrations, and their intermittent nature, when the engine/drivetrain shifts on hard(er) deceleration.

UPDATE

Existing transmission mount (15 months old) is still good, per my tech and Engine mounts are 5 months old, so these have been ruled out as causes.

Today, after replacing my worn-out (after only a year) Continental (crap) serpentine belt with a genuine Mercedes one, the vibration is significantly less but some still remains. I I believe it is being caused by the exhaust.

The vibration occurs mainly while stopped at traffic lights. It is essentially gone in Park and Neutral; and weakly present in Reverse.

Curiously, this pattern seems consistent with the secondary air pump cycling on and off (or high and low?). For example when arriving at red light there is a heavy-ish rumble that fades significantly about 3 seconds after coming to a complete stop. (With my E430, I could actually hear the air pump kick in when I came to a stop so I assume the behavior is the same in this car, with the pump adjusting the fuel/air mixture and causing downstream effects on combustion/exhaust output.)

Also, last week I noticed a metallic rattle on the first cold start of the day, precisely between 825-850 rpm. Moving above or below that narrow range stops it instantly. Looking around at the underside of the car I could feel the exhaust is a bit loose. Upon closer examination, I discovered the broken bracket/hangar assembly in the attached photo (rear, Driver side). Pushing lightly against the exhaust pipe in that area also instantly stops the aforesaid morning rattle, so it is clear the exhaust is oscillating enough to tap against one of its heat shields.

It therefore seems reasonable to conclude this same oscillation is transmitting the cabin vibration via the engine/transmission -- except when the transmission is disengaged in Neutral or Park.

Question: How involved, or not, would this fix be? I am assuming any muffler shop can do it.

UPDATE:

The source of the vibration was not the engine; not the engine mounts; not the transmission mount; and not even to a great extent -- although some -- due to the broken exhaust hangars.

It was the crap axles, i.e., GKN Loebro, that were installed.

Hearing GKN called "crap" may surprise people but, in my experience, they are, with *three* failures in 2 years! (Inner boots torn off.)They were problematic from the start, vibrating strongly when the car was in gear.

The worst was the left side and I decided to replace it myself this past weekend after the inner joint separated, with no effort, when I was replacing the wheel hub and bearing the prior week.

I bought a Cardone remanufactured axle for one reason: It was about 20.5" long, which I believe is the correct OEM length; vs the GKN and other aftermarket brands, which are about 19.5" long. I am convinced that is the reason for the inner boots tearing (all three times) and the vibration. The axles were too short. New, 20.5" reman axle is quiet and vibration-free.

I still have the other GKN on the passenger side, it is still vibrating but I don't feel it as much, and will replace that with genuine Mercedes since their passenger-side axles are oddly affordable (~$275 to $300) at the dealerships, after core.