OM617 Motor Mount DIY - PeachParts Mercedes-Benz Forum

rg2098 · #1 05-09-2006, 09:28 PM

A member asked me for a write up so it is. If anyone could take photos while using these steps as well as the exact fastener sizes please forward them to me to add and complete the DIY. I have found this the easiest method after doing motor mounts a few times.

1) Remove air cleaner assembly and unclip fan shroud (don't need to remove)
2) Remove center bolt from bottom of vehicle that mounts the engine to the mounts
3) Using a light vice grips to stop the shock from turning, unbolt the engine shocks from their top brackets.
4) Remove the engine shock upper brackets
5) Jack engine up using a board across the oil pan until most of the engine shocks are out of the hole only leaving the slim post above (you may be able to use a socket extension to push it down and "hook" it under the arm)(you will see what I mean)
6) Using the large hole uncovered by the engine shock mount, remove the inside motor mount bolt followed by the outside.
7) Slip in a new mount and assembly is the reverse of assembly.

NOTES:
-Clean out the allen head bolts well and use a hammer to fully seat the socket otherwise there is a chance you round it out.
-Don't jack the engine up without removing the mount center bolt and disconnecting the shocks from the brackets.
-Don't replace the trans mount while the motor mounts are loose. (don't ask how I know)

pawoSD · #2 05-10-2006, 12:58 AM

What do you do if you rounded out the central bolt inside one of the mounts (passenger side in our case)....this happened on the '83 as I was attempting to loosen it.

Is there a "best way" to tackle/get that bolt out???

JimmyL · #3 05-10-2006, 01:11 AM

Do NOT forget to undo the accelerator linkage from the firewall. We don't want that bent now, do we..........

I just had my motor mounts replaced, and I had one of the bolts rounded. The gentleman pounded a star socket into it in order to extract it.
Then he was nice enough to reuse said rounded bolt...

pawoSD · #4 05-10-2006, 01:22 AM

A star socket? Would this work well?? Or would there be a better method to removing it....

rg2098 · #5 05-10-2006, 06:52 AM

Quote:

Originally Posted by JimmyL

Do NOT forget to undo the accelerator linkage from the firewall. We don't want that bent now, do we..........

I just had my motor mounts replaced, and I had one of the bolts rounded. The gentleman pounded a star socket into it in order to extract it.
Then he was nice enough to reuse said rounded bolt...

I didn't have a problem with the linkage left on. There is enough slack and movability. It just takes a second to remove the long shaft between the firewall and valve cover and you can remove it if you want for piece of mind.

300TD · #6 05-10-2006, 07:19 AM

Don't forget to loosen the fan shroud to allow the engine to be jacked without pushing the fan against the shroud. Also, be careful that you don't bend a shifter rod (like I did) when jacking the engine.

Make sure to clean the inside of the bolt heads really well before trying to loosen them. They are usually packed with grime and the hex head does not seat well enough to work. Rounded hex heads are a REAL pain to remove!!!

vstech · #7 05-10-2006, 09:55 AM

I got a pretty good digital camera and several web sights to host pics, so I will digitally catalog my progress. I should start this saturday, maybe sooner!
And I think after I get the vehicle supported really well, I will pressure wash the underside of the vehicle. so don't be suprized when you can actually see the transmission mounts and bolts!
John

networkboy · #8 05-20-2007, 01:08 AM

Quote:

Originally Posted by pawoSD

What do you do if you rounded out the central bolt inside one of the mounts (passenger side in our case)....this happened on the '83 as I was attempting to loosen it.

Is there a "best way" to tackle/get that bolt out???

I've heard a Torx bit pounded in works. I have yet to try it. I may just wimp out and pay the indy to do the work. Once he gets that bolt out I have replacements waiting for him.
-nB

Chad300tdt · #9 04-07-2008, 04:07 PM

Quote:

Originally Posted by pawoSD

What do you do if you rounded out the central bolt inside one of the mounts (passenger side in our case)....this happened on the '83 as I was attempting to loosen it.

Is there a "best way" to tackle/get that bolt out???

I just dealt with this myself and they only thing that ended up working was to drill the head of the bolt off. It sounds much harder than it is. I used a 1/2" carbide drill bit and drilled until the head fell off. I used Aerokroil penetrating oil to lube the drill bit and I didn't use the drill at full speed. It took about 5 minutes and I was done. After the mount is separated from the mount arm, the remaining shaft of the bolt will unscrew with your fingers since there is no tension on it anymore. No kidding, the headless bolt shaft unscrews without any tool other than your hand.

I kept trying to find a solution other than drilling because I was afraid of the effort it would be, but it turned out to be much easier than I thought. Just wear goggles.

Here's my thread with pics:Stripped motor mount bolt - HELP needed ASAP

leathermang · #10 04-07-2008, 04:35 PM

Quote:

Originally Posted by Chad300tdt

the remaining shaft of the bolt will unscrew with your fingers since there is no tension on it anymore. No kidding, the headless bolt shaft unscrews without any tool other than your hand.

I kept trying to find a solution other than drilling because I was afraid of the effort it would be, but it turned out to be much easier than I thought. Just wear goggles.

Here's my thread with pics:Stripped motor mount bolt - HELP needed ASAP

Same thing with a stuck rounded out inside bolt holding the door jam plates on.. a drill which just fits into that allen hole will take it out in short order and then no problem turning it... no pressure, no resistance.

pawoSD · #11 04-07-2008, 04:40 PM

Good to hear! I'll just drill it out then when I replace the mounts on his car soon.....its going to be the combo mount/oil cooler lines project!

Chad300tdt · #12 04-07-2008, 04:44 PM

Quote:

Originally Posted by pawoSD

Good to hear! I'll just drill it out then when I replace the mounts on his car soon.....its going to be the combo mount/oil cooler lines project!

Consider cutting the hose fittings off the oil cooler nipples. I was careful and still galled the threads. Also the fittings on my oil filter housing are frozen together. I plan to cut the lines close to the fitting and unscrew everything out of the housing. Then I can carefully cut the hose fittings off those too and put the nipples back in the housing with some blue thread lock.

pawoSD · #13 04-07-2008, 04:49 PM

Quote:

Originally Posted by Chad300tdt

Consider cutting the hose fittings off the oil cooler nipples. I was careful and still galled the threads. Also the fittings on my oil filter housing are frozen together. I plan to cut the lines close to the fitting and unscrew everything out of the housing. Then I can carefully cut the hose fittings off those too and put the nipples back in the housing with some blue thread lock.

Oh I will, I have done the project twice before....and neither time was pleasant. I could not get them off my cooler successfully, even with carefully dremeling the nuts off, so I ended up with a brand new shiny Behr oil cooler. Cost: $302

I am going to try some new strategies and ideas in getting them off this time without damaging the threads.....but if they are super coroded together, there's not really much that can be done.

AYSCII · #14 06-22-2006, 12:13 PM

Hey, I'm in Raleigh NC also.... I just replaced the motor mounts on my 83 300D weekend before last. Yep, they are both the same. I reused the original heat shields, also of note, I had to cut down a L-shaped allen wrench to fit in there... I only removed the engine shock on the drivers side, as I remember.
Call me voice if you need anything... 919-291-4195 cell.

#15 10-03-2006, 11:04 PM

I changed mine mounts on Madeline tonight. I just removed the air cleaner, unclipped the radiator fan shroud, and unbolted the engine shocks. Accessing the inside bolt of the two smaller hex head bolts on the IP was a stinker. Next time I think I will cut the bend off of a 8mm and 10m Allen wrench and use than on a ratchet so that I have a long narrow tool to access the sockets. The job took about three hours by myself. With the modified tools that I mentioned I probably could have cut 40 minutes off the job.