Dead Motor Mount

[kampala]

I think it’s pretty obvious that this motor mount needed to be replaced!

This was the right side mount.   While I had everything removed to do the water pump, and alternator loose, I had direct access to the mount so it was easy and quick. 

[ja17]

Yes, and if you look at the bottom of the mount you will see where the metal part of the mount contacted the metal sub-frame, causing vibration!

[Tom in seattle]

I am pretty sure that a prior owner of my 250sl changed the two front motor mounts without changing the rear mount. This caused the motor height to increase enough that the oil cap dented the hood.  So I test this by making a wad of flour dough and putting it on the oil cap then gently closing the hood.

[Benz Dr.]

All the more reason not to drop your hood but close it carefully instead. Too many bad things can happen dropping hoods and letting them slam shut. 

Never seen new motor mounts do that but I can see where it could happen. Make sure it has the correct aluminum arms on the engine as sedan arms place the engine higher.

[Tom in seattle]

Ah ha!  Very hood to know.  My car has an SE motor and I wonder if this could be the reason the dent happened .  How can this issue be eliminated?  Are there part numbers on the big aluminum brackets?

[dirkbalter]

Ah ha!  Very hood to know.  My car has an SE motor and I wonder if this could be the reason the dent happened .  How can this issue be eliminated?  Are there part numbers on the big aluminum brackets?

Tom,
Take a look here.
https://www.sl113.org/wiki/Engine/EngineSupportArms

[Tom in seattle]

Dirk thank you.  I will definitely look and see which I have!

[Tom in seattle]

I searched the web for the proper support arms and found they were available from MB directly and at a lower cost than from resellers.  Getting the old improper arms out was a challenge but if you’ve got time on your hands it can be done.

[Todd]

This is the next job on my coupe.  Was able to get the OE part numbers for the red-dot right, and plain left.  Ordered them and the engine "torque damper" rod over the weekend.

[JohnnyC]

Todd, and others,  Is there a left and right mount difference?  I have two new mounts both with the red dots on them. Do I need to get one without the red dot? I haven’t heard anything about this being a left and right mount.

Cheers and thank you,
John

[Todd]

The red dot mount is made of a harder rubber, which makes it able to withstand the torque of the engine.  It goes on the right side.  The mount that doesn't have the red dot, goes on the left side.

I don't know if it matters if 2 red-dot mounts are used, and I don't know if maybe the factory decided that 2 red-dots were an updated method of better supporting the engine.

[dirkbalter]

The red dot mount is made of a harder rubber, which makes it able to withstand the torque of the engine.  It goes on the right side.  The mount that doesn't have the red dot, goes on the left side.

I don't know if it matters if 2 red-dot mounts are used, and I don't know if maybe the factory decided that 2 red-dots were an updated method of better supporting the engine.

Surprised to read that. I bought my motor mounts from MB and was told the they are the same (now). Both with one red dot.

[Todd]

MB must have decided that the tougher mount was a better choice for both sides, which makes sense.  Maybe early on in the original testing of the cars, they achieved better vibration damping using one softer mount, so the cars were slightly quieter, or had less "felt" vibration in the passenger compartment.  But maybe they started seeing repeated "early" failures of the soft mount on the left, due to how much the big 6 cylinder weighs.  I don't know, I'm just guessing.   

I sent my VIN to an MB parts supplier and they came back with 2 different numbers, at about $114ea, and that was for a red-dot, and a plain. 

[mauro12]

What is the best source for engine mounts ? I bought mine from a German website and they are oem.

[dirkbalter]

What is the best source for engine mounts ? I bought mine from a German website and they are oem.

The best and likely most expensive source is MB, if you don’t want to take a chance. Why are you asking if you just bought some?

[mauro12]

I wanted to make sure that my choice was good . Sometimes when you buy something from mercedes is exactly the same product only with Mercedes’ logo on the box .