DIY: Motor mounts on V12 SL models
 

I would like to provide this DIY for you guys who want to tackle a real project and are comfortable working on their own cars. Worn out or leaking motor mounts are just a part of owning a Mercedes. Our delightful torque monsters only make it a more frequent experience. I will try to illustrate as best as possible what I am explaining, but it was a little hard to stop and photograph everything.

First off, the tool list:
You need a full array of 1/4", 3/8", and 1/2" metric sockets and a set of the Etorx(or inverted torx) sockets also. If you don't have all of those, go back to those girly little DIY things posted elsewhere on this forum.
8, 13, 16-19, 21, 27, 32mm wrenches(combination and ratcheting 8 and 13mms)
T60 torx socket
Assorted pliers, including hose clamp pliers
Assorted flat and phillips head screwdrivers
A lift
A lifting table and cradle to fit the R230
A/C machine
Several fluid drain pans

First thing is diagnosis of the motor mounts. Once you rack the car and lift it up, remove the under shields, and examine the small black strap wrapped around the mount. It is there to help retain the engine in position should the mount fail(holeshots). If it is loose, your mounts have collapsed. They may or may not provide sufficient dampening and you may notice a rough idle. If you have a vibration in park when you rev the engine, you probably need to replace the transmission mount(that is a cake walk). Also look around the mount in the area below it. If you see any dried black liquid(like very thin tar) your mounts have ruptured and need replaced. Make sure the leak is from around the mount and is not from a torn bushing in a suspension arm.

This car had a ruptured mount on the left and a collapsed right one.

Now lower the car back down and decide if you really want to undertake this.
Next is to remove the engine
Start by disconnecting both negative battery cables
Remove the engine covers and the air boxes box. Make sure you unplug the air pressure sensors first!
Remove the false rear wall behind the engine
Now evacuate the AC system
While that is going on open up the module box and unplug the main engine wiring harness from the ME control unit. Feed it up out from under the cowl and drape it over the engine
Remove the braided stainless fuel line at the fuel rail on the intake
Remove the cooling fan assembly
Unplug the plunger solenoid on the ABC Pump, and remove the hoses between the ABC and PS reservoirs
Disconnect the low temp cooling circuit hoses from the pipes under the coil packs that run to the heat exchanger plumbing. This will make a small mess as there is no drain for the low temp system
Raise the car back up, drain the coolant from the left side of the radiator by opening the small red valve
Disconnect the lower radiator hose from the engine
Unplug the connector going to the valve body
Remove the complete exhaust
Remove the transmission cross member to disconnect the drive shaft from the trans, reinstall the cross member for now, leaving the ground strap loose
Remove the shift linkage from the transmission
Remove the bolt from the steering shaft and press the upper shaft out of the shaft mounted to the steering rack
Disconnect the 2 large oil lines going to the oil cooler
Remove the heat shield on the outside passenger floorboard to access the starter cables, and remove them
Remove the alternator coolant return hose
Remove the return hose from the steering rack and unplug the speed sensitive solenoid
Remove the lower control arm and thrust arm bolts, swing those out of the way
Lower the car again
Disconnect the lower and upper radiator hoses from the engine
Disconnect the rear coolant hose from the engine to the firewall
Disconnect both trans cooler hoses from the passenger side of the radiator
Raise the car back up, roll the lifting table underneath it with the cradle on top of it. Use a screw jack to support the rear of the car. You will now be removing a significant portion of the front axle weight from the car and you do not want to watch your car topple off the back of the lift
Raise the lifting table up to safely unbolt the subframe and cross member
Unbolt the 4 subframe bolts and unbolt the transmission cross member from the vehicle(it can stay on the transmission)
SLOWLY lower the entire front of the powertrain with the subframe attached while your buddies watch for hangups and forgotten hoses or wires
Once the whole thing is lowered, remove the lower bolts from the motor mounts, use an engine crane to lift up the engine about 3 inches
Remove the engine mount arms from the block, you can actually just unbolt them and kind of leave them in place(this is a lot easier said than done, figure on at least a half hour)
Once the arms are loose, you can remove the 3 top bolts on each mount and exchange the old busted joint for the new hotness.
Lower the engine back down and reattach the lower bolts.
Proceed to reinstall in reverse order
Fill and bleed all systems, correct oil levels in engine and transmission
Refill AC and replace the receiver drier
Clear all the DTCs you created by doing this
Perform a good road test to ensure there are no leaks

Hope this helps!

Nick

More Pics!!

Still more!

Keep em coming!

Guess there's more than I thought....

Wow...

This should be it for now.

amazing post, thank you. How many miles were on the car? I am worried about mine going, and my understanding is that there is no way other thn removing the engine to replace them?

:popcorn:

wow im a mechainc and it looks like i dont want to do mine lol
great pics thx

Big thanks for the info nick, looks like an epic undertaking!

The car has approximately 40000 well cared for miles. Once finding out the mounts were bad, I removed the exhaust. We spent about an hour looking at ways to possibly get around removing the engine, but there are 3 bolts on top of the mount that need to be removed, and they are tucked under the turbo plumbing. It was determined that the only way to remove those bolts was to disconnect the motor mount arms from the block(not an easy task). I think that this job is best left for the dealer. By the way, warranty time is 13.3 hours. I think if I did 2 of these jobs a week, I could possibly meet that time, but this time I will probably be in it 17 hours.


Nick

Nice. Thanks for the pics!! Is that a 600? I remember my exhaust wheels looking a little bit larger than those.

eff u ;)

No, it is a 65. The owner is a forum member that shall remain anonymous unless he/she chooses to identify themselves.

Nick

Nick, thanks for the post! Amazing job. :bow:

If you don't mind me asking could you take measurements of the turbo housing, Exhaust and intake? Just want to put to rest the idea that the turbo hosuing of the 600 models Vs the 65 are different. This should help me clear things up. :y

Too late, she is back in the car! The castings for the turbos are different from 600 to 65. If you are talking about the diameters of the inlet from the airbox and the outlet to the exhaust pipe, they are the same diameters. I know this because 65 airboxes will fit on a 600 and the exhaust clamps are the same for both models where the flanges from the turbo and the cat pipes mate. Will they bolt up to a 600? Yes.

Nick

Thanks. Appreciate the effort. :y

great job nick, a little off topic but I love your signature

Thank you, on all accounts:D

Nick

DIY - :rolf::rolf::rolf::rolf::rolf:

I will admit that this sounds like quite a bit, but after replacing an engine in my CL, acura cl that is :'( there isn't too much more that has to be done aside from their being more exhaust, no abc system and some other small stuff......props on doing the work though, I am a bit terrified to work on anything with more than 8 pistons. Did you get any form of shop manual/all data to do this or did you just tear into it? I'm just curious about what torque specs should be used and other install stuff.

I'm also confident that if I ever undertook this project, I would have to install bigger turbos before I could put it back together....:D

Wow :eek:

Thanks for the posting...Its very nice to read and reliable....
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