BruNo

hi!

my 2001 C240 (v6) just had new sparkplugs, mass airflow sensor. but i still have this very light engine shake, i can only feel the shaking during "idling" especially on the transmission tunnel along the center console of the front seats where my leg rests. we have run a star diagnostic test....no faults were found except for some misfiring in some cylinders...which are "stored faults" when i happened to fill up with some contaminated fuel a few months back. also, fuel pressure on the injectors have also been checked thru the star computer, and all 6 injectors are fine. in short, no problems were found through the star diagnosis laptop.

the car's rpm at idle is steady, it runs fast..accelerates smoothly. the only problem is the very slight shake at idle. in one driving cycle, sometimes the engine shakes, sometimes, it does not...so its semi-random.but i know its there.

any ideas???? i didnt change my fuel filter yet, but i dont think its the problem bcoz i dont have any problem with acceleration or when im driving fast.

could it be "motor mounts"??? my car is an early 2000 production, so its one of the very firsts C class. i only have 7,500miles now since brandnew.

kinda offtopic...but....also, where is the purge valve located?

Mike T.

You don't mention if this is a new development or something the car's had since new. I imagine it's the former.

If so, it could be the engine mounts.

The Mercedes V-6 is not a smooth engine, due to its 90 degree cylinder bank spacing, and so it relies unduly upon mitigative engineering measures to minimise this problem. These include the balance shaft and the engine mounts.

BruNo

the shaking is a new devt. about 2-3months ago..but i couldnt imagine engine mounts dying at 7,500miles, though ived heard that engine mounts are a common problem on the c class when it was new in 2000 and the new E class....

anyone experienced the same??or has replaced theirs?????

xc240x

i have the same problem but it is more obvious in gear (d or r). I imagine it is the tranny mount. But it sounds exactly like the same problem you are having. Mine is an 01 240 as well so this might be a common problem. although I have 38k miles on mine. I have been hesitant to take it to the dealer due to the fact it is lowered, has the Rieger kit on it and has an aftermarket exhaust. I'm considering getting a tech to do it on the side at my shop so I can be sure the car won't get damaged when trying to lift it. I'd rather pay some money and have it done safely under my supervision than having to go after a dealer to pay for damaged sideskirts etc. I'd like to know if they have to drop the exhaust to do the tranny mount, if they do, i'd definitely want to do it here b/c the Rieger rear lip goes around the exhaust tips.

BruNo

ey xc240x.....seems im not alone....

so you too have:

a. faint engine shake at idle "P" or "N"
b. no engine shake when revving the engine above 1000rpm or while driving.
c. engine runs fine.
d. no fault codes found.

keep me posted on your fix.

Sincity

I have the same problems with my ML320 with 62k mi. The harmonic balancer looks fine....

TNblkc230wz

I'm not sure how slight the sake is, but most engines will have some slight shake to them. I haven't owned any cars that I couldn't feel some engine vibration at idle from time-to-time. Even my Honda V6's would occasionally shake. I do occassionally feel some vibration from my 3.2 at idle. I consider it normal. It does it infrequently, but it will occassionally do it. There is a lot going on with the engine electronics, I think sometimes most of the variable parameter settings will be at the outside limits, but within the specified limits none-the-less.

xc240x

I think Bruno and I both have the same problem... mine is more noticible in gear though Bruno. It's pretty obvious when you have the dorr open and it shakes up and down a bit. When i'm in a quiet area and i'm stopped, I let go of the brake pedal and accelerate slightly, then let off and do it again so i can stay in 1st gear. when i let off i hear nothing out of the ordinary but as long as it's in first and i reaccellerate a bit i hear a low clank sound. Like i said i imagine my tranny mount is pretty damaged. As to why... I have no idea.

pookie

i now have this problem. 26k miles.

jrct9454

Our C240 has always had a little idle shake, more than most V6s from other makers, but never bothersome enough for me to ask them to do anything about it. It will vary by engine load, and go away completely at anything over 800 rpm...just hasn't made it on my problem radar screen...

pookie

i know that shake. that is ok, i had that before today. however, now for some odd and ramdom reason i would have a shake so vivid that it feels like i'm getting a massage. happens at any gear and comes and goes. i'll go to the dealer to see if there are any error codes, luckily something will turn up and let you guys know.

shh

Hi all, my first time posting.... :p

I've the same problem with my 01 c240. Had that "massage" randomly/occasionally for the past few years. It happens right before I stop the car (... while slowing down), until I put it to neutral and gives it a little gas.... actually feels like when someone is first learning to drive a stick-shift.

Brought the car to the dealer several times, their usual reply "cannot replicate/re-produce the problem". They always check and find no errors, but problem persisted.

Hope you have better luck at the dealer, and please let us know how it goes

Thanks....

CHATMANR

I had the same issues; and it was the result of 2 broken motor mounts. Cost: 1500.00. Because I had the extended warrn., it was fixed for free...

BruNo

hey keep me posted on ur fixes,mine is still unsolved,its like the engine is running slightly rougher than normal while idling,and this causes the random shaking.

pookie

went to the dealer. they checked it out. no error codes. what is worse is the car wouldn't shake either. it's like a freaking game. the car has a mind of its own.

pookie

dang. didn't see your post before i left. maybe that is it (i'll see next week)

f00b4r

I have been having a rough idle problem with my 2001 C240 every once and a while. One particularly bad time the car idled so bad it almost stalled. When the engine started behaving better again it had trouble accelerating beyond 30 (I was told because the engine shutoff 3 cylinders). They replaced the catalytic convertor (at 20k miles!!).


I didnt have troubles for a while after that... But it started again... ostly when slowing down to a stop (like coasting to a stop sign). I was able to reproduce it several times while a tech was riding with me. I dont remember exactly what they replaced but it didn't seem to fix it. I brought it back in and they put some fuel injector cleaner in it and that seemed to do the trick.

The tech explained that when the engine is not at full load some of the cylinders will be "turned off" and that gives the fuel injectors a chance to plug up. So now everytime I start having this problem (it has happened once more after that) I just put some fuel injector cleaner into my gas and the problem goes away.

.elijah.

Where did you take it in? I have about 65K and my C240 is starting to shake quite a bit. I'm in San Diego as well. What did you report too? to which Service Advisor? I asked a couple yesterday at MBSD and they said that they have to check whether these are covered. I also have the 100K warranty.

aerodragon

i did not see this problem with my car but while I brought my car once for regular maintenance, the SA asked me about motor mount; he then replaced it just to be on the safe side.

CHATMANR

I took it in to MBSD. I don't remember which tech it was, but IT IS covered under the 100k warranty [assuming you bought it at MBSD].

laneshift

About to take my 240 in for the same issues. I also noticed that when I reverse and I don't apply some throttle, the car seems to just about die, it feels like engaging a clutch without gas!

jcnash

I have the same problem on my 02 coupe. Ive also noticed that it seems to happen right after I set off after a cold start.

Also, right after it shakes when im stopped (as a light for example), when I start to move the tranny goes nuts and doesnt shift for a while and i have no power till it kicks in with a jolt.

Let me know how it goes at the garage.

Glyn M Ruck

My C240 suffers zero engine shake. The 90 degree V is perfectly sorted with the balance shaft.

Usual causes of shake

Coils & plug wires
Engine & transmission mounts - Check transmission mount
Broken honeycomb in one of the Cats
Dirty injectors - Add Techron concentrate to fuel.
Dirty or damaged throttle body or damaged TB actuator.
CPS

In abnormal cases - Torque Converter lock up clutches not disengaging properly - This should cause the car to creep & throw a code.

Jack_2001C240

I know this post is over 5 years old, but I did not know the 2001 C240, which I have also, has cylinder deactivation of 3 cylinders.

Glyn M Ruck

It doesn't - all cylinders shut down on trailing throttle only. ie closed throttle.