R129 Engine & Transmission Mount Replacement - Mercedes-Benz Forum

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post #1 of 116 (permalink) Old 03-25-2007, 06:47 PM Thread Starter
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R129 Engine & Transmission Mount Replacement

Originally Posted by bullockandrew

OK, I tried that (without driving into anything): engine rocks left and right but no movement upwards as far as I can tell.

I am no mechanic, so should I just ask the garage to chance the engine mounts?

Thanks as always for your advice.


Glad you didn't run anyone over, especially your mum-in-law.

It sounds to me that at least 1 mount is bad; these are replaced in pairs at around $100@ (Boge) + labor. If you're into the car this far, ask your tech to inspect the trans mount as well. As I may have said earlier, I just had this done and it eliminated the vibration. So your work list is 2 motor mounts for sure, inspect trans mount and replace if worn, and have the tech check the steering shock; change as required. Good Luck and have fun!

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post #2 of 116 (permalink) Old 04-18-2007, 07:16 PM
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I changed my motor in less than 3 hours,,,,and if they were toast, I changed the trans mount as well. 6 hours total, only because I am not a Mercedes Mechanic. BUT, I was quoted $1.2K. I know, as an engineer building big corporate designs, I charge more than a Mercedes mechanic!!! BUT, I justify it by the fact that I REALLY do fix the problem that the client came to me with,,,and if it leads to another, (as I hear EVERY time), I want to see why. Most won't.
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post #3 of 116 (permalink) Old 06-20-2007, 08:01 AM Thread Starter
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Hello Andrew,
I recall your earlier post of several months ago when most concluded that your engine mounts were failing and the 'test' I asked you to do. I think it's safe to say your mounts are now completely shot and since the engine is riding lower onto the frame, in addition to placing additional stress on the transmission/drivetrain geometry due to the rock n' roll of your engine, the harmonics of the car are bringing more of the vibrations into the cabin where you can feel them more acutely. (this is a long winded way of saying what Lynn did...'get 'em done'!)

I also recall your commenting on the large expense to have this work done by your MB Tech. I would suggest that engine and trans mounts are more a 'General Automotive Skill' job than necessarily MB specific. In other words, any shop/garage with a good reputation should be able to handle this for you, and probably at lower rates. That said, I believe you need to stablize the drivetrain to both solve your problem and keep your repairs from escalating and becoming even more expensive.

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post #4 of 116 (permalink) Old 06-20-2007, 10:18 AM Thread Starter
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Lynn, I'm impressed with your memory...at my age, I couldn't tell you what I had for lunch yesterday!

Your're right, I did the engine and trans mounts several months ago to cure the vibration problem I was having at the time that, I too, attributed originally to tires/wheels. The 'brilliant command of the obvious' tip off was the vibrations occurred at all speeds, even standing still!

My tech, in determining whether to replace both mount assemblies, did the engine's first after marking the position of the trans mounts. When the new engine mounts were in, this 'lifted' the trans upward about 3/4". By rights, it shouldn't have moved at all. The extra strain placed on the trans mounts from the failing engine mounts caused the premature failure of the trans mounts, so both sets got done....vibration gone.

I think if Andrew shops around for this work, he can probably get done for less money than an MB Specialist would charge. This job is 'heavy lifting' not 'rocket science'.

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post #5 of 116 (permalink) Old 07-06-2007, 08:35 PM
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Originally Posted by SunGuy61
Originally Posted by lynns
Bob, please give me an idea as to what the average mileage is when the engine mounts need to be replaced?
Mine were done at ~54K.
That's one set of Engine Mounts at 54K and one at 40K miles. Sounds like it is probably a good idea to have them checked around 45K miles if you notice a strange feeling from the drive line.

FWIW, I have had several cars that were known to go through engine mounts.

In order to determine if the mounts were bad I would put the Parking Brake on, apply the Foot Brake, put the car in gear, gently raise the engine RPM's, while I had another person stand to the side of the car with engine bonnet open and tell me if they could see the engine lift up as I raised and lowered the RPM's.
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post #6 of 116 (permalink) Old 07-21-2007, 01:41 PM
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I have been doing some interesting reading today. I have been looking over the service records of our car. I just wanted to see if any of the suggested repairs/maintenance they dealership suggested needed to be done. While doing that I came across some outrageous bills the previous owner threw down the plastic for. Also somewhat reassuring that these major repairs have been done, and hopefully won't need to be done again. I will start with these and then get your thoughts on repairs suggested with parts and labor. I am hoping some of them as noted above are DIY w help.
Major repairs
8-2000 at 70,845 the control unit was replaced........1,300 part
3-2000 at 61,000 the oiler tubes replaced.................699.00 parts/labor
under warranty re-dyed the door panel once and then ended up replacing
instrument panel replaced
Back of Drivers seat re-dyed and then replaced
It would be interesting to see prices of warranty work but all have n/c
Now for suggested repairs
Left tie rod assemply 1293300203- 98.00 plus 1hr labor plus alignment(doing for sure)
brakes all around but only rotors for the back. Front rotors where replaced at 61,000
Frt Upper Strut Mounts 1243200473 122.00 each 3.5hrs labor
Engine Mounts 1402402217 185.00 each 3.0hrs labor
Trans Mount 2202400218 52.00 .8hrs labor

Serp Belt 0119974592 78.00 1.2hrs labor. Replaced at 83,000 now at 94,000 is this needed?
Is there a reseal kit for my p/s pump? leaking a little not urgent
Spark Plus suggested but done at 61,000, does this need to be done? Also only eight needed and that what was replaced last time. I thought we had 16 total?
Coolant Flush suggested but done at 83,000 still needed?
Tranny service
gasket 1402770086 16.06
Filter 1402770095 19.40
ETF 001989210310 19.40 x 5
drain plug seal 1402710060 2.00 tranny service 1.5hr labor
Labor is approx 89.95 hr also

Looks like the car will be getting some of the paycheck this month. Other than replacing the the cylinders, this is the first time we have spent money on repairs. Not bad for owning over 2 years.

Your thoughts appreciated,

Some do, some don't, some will, some won't, but I might!
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post #7 of 116 (permalink) Old 07-31-2007, 07:37 AM
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Replacing Motor Mounts

Is that something a fairly mechanical guy can do? 1992 500 SL...thanks!
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post #8 of 116 (permalink) Old 08-02-2007, 12:32 PM
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The R129 Tech DVD and WIS instructions say to lift the engine from above using a hoist or similar, but you can use a jack from below to support the engine.
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post #9 of 116 (permalink) Old 08-03-2007, 02:18 PM
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This post came in the right time.

I brought my 2000 SL500 in for regular oil change at a MB dealer ($100, don't kill me over this, the dealership is just 2 mins away and my trusted mechanic is a good 45 minutes away) and they told me I need to change my motor mount and steering shocks, cost quoted USD $1200+.

Rather than trusting the dealership, I than decide to drive 45 mins to my mechanic and the problems checked out. But it cost only $500 to fix the problems. Labor charged was only $190, the rests are parts.

Dealership quoted me 4 hours of labor for engine mount, and 1 hours for steering shocks. My mechanic did the mount in about 2 hours. No charge to change the steering shocks, just have to pay for parts.

My Mechanic showed me the old motor mount, they were not in too bad of a shape, one is fine and one just started leaking oil (not in the shape that the dealership described). Anyway...

The replacement actually elimated the "knock" I get from acceleration and the "shakes" I experienced when the car is idle.

What I do not know, and if someone can educate me is, what does a steering shocks do and located?

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post #10 of 116 (permalink) Old 08-03-2007, 07:47 PM
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One per car.
Steering dumper/shock is held by two bolds between frame & R/L wheel tie rods .
When you go over bumps the front tires shake and it transfers to the steering
wheel the dumper slows it down.
One hour for two bolds? may be lunch is also inclouded .
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