DML756

I note a throbbing vibration at low speed and RPM (22mph, 1400 RPM). Have been told this is a pulsation damper failure. Both ABC front struts and rear valve block have been replaced w/in 10,000miles. What's next?

Also, picking up vibration at high highway speeds (80mph), but this might be a wheel balance or tire issue. Or, does the damper problem manifest at high speeds?

mrbenzes

Is it when shifting gears 1-2 and especially when the car is cold? If so, it is probably the damper. This is a separate system from the ABC, so it is not related. I have read thet the damper is a DIY job, if you dont mind getting some ATF fluid on you... might save you some $$$.

mrbenzes

Oh yeah, I forgot to add, try 'Comfort' mode and the 1-2 shift pulse should go away...only because you start from a stop in 2nd gear. Mine does this when cold, and I basically ignore it..it does not happen when warmed up after 10 mins or so of driving.
Mike

DML756

To those who replied:

No keeps happening when the car is well warmed up. I now hear that I need new motor mounts..Chambers in Somerville MA quotes 12 hours per front and rear!!!! Opinions? Car has 113,000 mile but pretty sedate driving.

mrbenzes

12 hours each is insanity, you could pull the engine and tranny out and put it back in in 12 hours!
I'll check the maintenance manuals and let you know what it will take...are you a DIY kind of person?

I did mine in my E420 last weekend and it took me three hours, but that was an extreme case...the mounts were too big to get out and in..I finally succeeded.
Mike

mrbenzes

There is another thread along side this one that also is describing a throbbing and they think it may be the Supercharger clutch..that may also be something tho consider.
Mike

DML756

Thanks again Mike. Will try to find supercharger thread. My independent mech. emailed me to say that S55 mounts were hard to change out than regular S class, see below:


"I’ve looked at them (mounts) before, no visible defects.

It’s a large job on your car to do the left mount. The ABC pump needs to come out, then the a/c compressor partially. It’s around $1100 for both. Have you done the ABC pump yet?

Probably not worth doing in this case. If it gets worse it may eventually be obvious what the source is."

mrbenzes

I replaced the mounts in my e420 a few weeks ago and they were really noticeable...vibrations almost constantly and a thump under heavy acceleration...it was there all of the time and I had no question they were the issue...however, they looked fairly normal visually and when I had them out, they were only about 1/2 inch shorter than the new ones, with no rips or damage...it is totally smooth now. I still think your issue is with the pulsation damper....I'll send you something soon.

Mike

mrbenzes

I went to ESRA and it turns out that the pulsation damper that I have been blaming is simply and ABC pulsation damper...I dont know why it thought it was a transmission damper...but it is strictly ABC.
I have attached the ESRA data.
Mike

mrbenzes

I went back to ESRA and checked on replacing the engine mounts...it looks like the alternator and ABC pump are supposed to come out..ouch. sometimes MB calls for these extreme steps and they aren't always necessary..but you can bet the S55K engine will be in there tightly...send me a message offline and I will forward the PDF docs to you.
mike.thomas at aosepc.com
Mike

PillDrive

I would do the transmission mount first and see how the vibrations are after that...then i would do the abc pulsation damper...last is the engine mounts....i have done all of those and each one fixed a certain vibration....btw the engine mounts are not so bad.

DML756

Pulsation ABC damper was replaced last week and this did not clear up the problem, despite costing over $900...

Dealership tech says motor mounts, but over 12 hours job (@ $125/hr...)

sushistrip

I know this is an old post, but having just done engine mounts I wanted to correct some information here.

If you are careful, you can remove both mounts by removing the steering rack retaining plate, which lets the steering rack hang down a bit, and jacking up the engine a few inches. BE CAREFUL when jacking up the engine, just be smart about it. If you jack it up and there's still not a enough room to pull the mounts, give it a couple more pumps and try again. They won't just drop out, you'll need to wrestle them a bit but they should come out fine. When putting the new ones back in you need to screw the top bolt in a few threads, otherwise if you drop the engine on the mount the top hole won't line up. You'll need an 18mm socket and crowfoot wrench to unbolt/bolt the steering rack retaining plate back in, and the bolts require 85Nm. Be cognizant of the orientation of the old mounts as you're pulling them out, if yours are leaking they will dump oil all over you and it smells absolutely foul.

You'll also need the 16mm offset wrench for cracking/torqueing the top mount bolts:

JohnLane

I always lolled when the techs at MB told me 12 hours to do mounts in those. The FIRST time I gave my 221 S-65 mounts they were done in just over two hours and I’m no hero, was not practiced at it and was not in a hurry.

Some wonder why the Stealership is referred to as such. I don’t.