OM617 Motor Mount DIY
 

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)

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

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...:mad: :mad:

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

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.

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!!!

Thanks Adam, I will make good use of this and Post Pics along the way.
 

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

I never undid my throttle linkage or shifter linkage or fan shroud when I did mine, and it came out fine.....:confused: I only jacket it up enough to just barely slide the mounts out though.

Its easier to access the inside bolts with the engine high, the shroud does need to be unclipped because the fan will catch on the upper lip. The trans doesn't move that much when jacking up the engine and the shift rod is in no danger.

Identical?
 

So the left and right engine mounts are identical?

A good first step is a trip to the steam cleaner or pressure washer.

A mention of the transmission mount is in order.

And if you continue to raise the engine after the fan hits the shroud, something has to give. How difficult is it to remove two clips from the shroud? No more difficult than disconnecting the accelerator linkage, which is also a very smart thing to do.

Jwj....
 

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.

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.

Replaced mine on my 240d tonight, I should put pics up of my drivers side mount. Terrible. I was unable to fit the heat shields back in, because I didn't unclip the shroud or remove the shocks, so I couldn't get the engine high enough, looking back its probably not a good idea, but mounts are cheap if they go bad and my car drives like new now... Definitely difficult to get to the hex under the IP but everything else went rather smoothly.

pics
 

PIcs please.... I am getting ready to do this myself and I am questioning the mounts because they dont look like whats on the car. Well the bottom half does and the top half with that shield and that cone shaped rubber under it does not... Any ideas?

I have 2 new mounts that look identical and are ready to go in when I figure this out...


Thanks guys!

:book:

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

They wont look like the mounts, until you take out the center bolt from underneath and jack up the engine, then you can pull the shield out to reveal the mount. Hope this helps.

also
 

Hey why not tack weld that allen in the bolt head to get it out.. er or pound it in there with some jb-weld gunked on it, to sit over night and have at it the next mornin...:D

The size allens for the job on a 85 300SD
 

The size allens I have on my Benz are a 8mm for the motor mount and 6mm for the 2 mounting bolts on top. The shock bolts are 10mm and I removed the shock and the bracket from the block the 8mm bolt screws into only because I was changing the oil cooler lines also and the only way to get them out was to remove the mount and bracket. Made the job much easier.

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.:cool:

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:http://www.peachparts.com/shopforum/diesel-discussion/212326-stripped-motor-mount-bolt-help-needed-asap.html

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.

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! :D ;)

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 :eek: 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.

http://www.peachparts.com/shopforum/diesel-discussion/218681-do-i-need-find-oil-cooler.html

Check out post #6, Charlie linked another thread that talks about how to fix an oil cooler that has bad threads. Apparently, MB has screw in nipples that you can tap into the oil cooler.:cool:

Engine mount
 

1984 300d turbo 148k
use a 7 mm open end to hold the engine shock from turning ON the
SHAFT botton of shock, a 10 mm socket 3/8 the same time, install new
engine shock mounting kit top and botton diy

Just did my mounts. The driver's side mount rubber was disintegrated, collapsed and in chunks. I PB'd underneath and lifted up the engine just enough to spin an allen on the inside 6mm bolt. Access from the top is easy on the outboard bolts. I cleaned up all the bolts and the mounted nuts with brake cleaner and air and was very careful not to cross thread the soft aluminum engine mounts. I even used a metric tap just be sure. everything went together hand tight. Did take 2+ hours but easier than I thought it would be.

Just a couple things. Got one center bolt out (used a 5/16 allen socket...I know, not a good idea). I can't get the other one out. The piece of metal with the access hole in it to get the bolt out looks shorn and the motor mount has pressed it down about a half inch. Consequently, the edge of the hole goes right across the center of the bolt head. I was thinking I could jack the engine up a bit , pound that piece of metal out of the way, and access the center bolt that way. Can I replace the piece of metal? Do I need to? I'm thinking the motor mount rests on it.

Also, what do the engine shocks look like? Do I access them from above or below? Obviously this is my first major DIY car project.

Thanks for any help.

don't know if my 300d is different but I have a few things to add to the article that I think would be VERY helpful.

FIRST: there is no list of tools! (10mm socket, 10 mm wrench, 6mm HEX socket, 8mm HEX socket, vice grips, 3/8 inch ratchet with a short and medium extender, 3/8 inch universal joint)

SECOND: I have no idea what the original author meant by his step 2) I can only assume he means the two (one for each side) 8mm hex bolts accessed from the bottom that sandwich the motor mount from the engine to the frame . The 6mm hex socket will remove the hex bolts that hold the engine mount to the frame from the top.

everything else seems pretty straight forward. sorry , no pictures

Parts list and pic
 

I did my mounts and engine shocks as part of an overall rehab last week. I think they were the 1983 originals since I've got service records back through '94 and there was no mention of them being replaced.

Parts list - the shock mounts were the priciest, but mine were completely disintegrated:

Engine Shock/Damper; Left/Right (this is a small shock absorber)

Engine/Motor Mount; Left/Right; Front (large block of rubber)

Engine Shock/Damper; Engine Shock Mount at Bottom (this is a bonded metal/rubber sleeve to hold the shock)

Engine Shock/Damper; Engine Shock Mounting Kit (new rubber bushings for the shock)

In the image, the mount on the left was under the driver's side and was saturated with oil and PS fluid and was losing chunks of rubber, the one on the right was under the turbo and flattened but more/less intact. The engine sits maybe half an inch higher now, judged by increased clearance between the engine and the cross-member.

I did mine this afternoon after reading the above....and the manual.
The inner 6mm bolt (under the IP) was easy to get to after the engine was jacked up and I took off the long AC compressor mounting bolt closest to the center of the car. Gave me enough room for an allen socket and 3/8" rachet.

The hardest part was getting the engine moved around to get the 8mm bottom bolts back in. Got 'em with the engine jacked back up (lifted off the new mounts), moved the engine a bit using a crow bar and a pry bay.

OMG, it sounds like a Benz again, not a bucket of bolts

More data
 

Heat shield OM617 engine mount
http://www.peachparts.com/shopforum/diesel-discussion/121452-heat-shield-om617-engine-mount-post873875.html



Bad engine mounts
http://www.peachparts.com/shopforum/diesel-discussion/121286-bad-engine-mounts-post868339.html

Engine / motor mount DIY
http://www.peachparts.com/shopforum/diesel-discussion/146482-engine-motor-mount-diy-post1104023.html

Having just worked this to some extent to remove oil cooler hoses, Ill add a few notes... this is a good thread.

-For the engine shock, there is a 7mm flat section which a small wrench can slide on, which may help prevent dmage to the shock. The two mount nuts and the nuts for the shock shaft all use a 10mm socket.

-Easiest way to get the 8mm main allen on the mount is via a high quality hex socket on an extension. Get it in there after cleaning, good and tight, and use the ratchet for leverage, keeping the extension shaft very rigid and straight.

-DO remove the fan shroud clips and the throttle linkage. My mounts were nearly new, but to get enough height to remove the heat shields and have space to get the oil cooler hoses out, the engine needs to go fairly high. Be careful with the shroud near the radiator hose/neck. The shroud will push up a bit when the engine is high enough to be able to service new mounts.

-The inner bolts are a pain. Removing the shock and/or heat shield still does not give you topside access or space to place an allen socket. It just doesnt line up:

http://i83.photobucket.com/albums/j3...D/IMG_2254.jpg

I don't have a good solution, as I didnt need to remove the mount so left as-is. It would be good for folks to explain their techniques.

Did mine this morning...much easier than expected. One was in crumbles and one wasn't to bad. Got the drivers side up and new one in, and when I went to do the passenger side I found that the main center bolt was missing! Glad there are other bolts that help support the engine...that could've led to a major problem.

Now it sounds like a new car again!

Bump for floridian member!

Just did this myself on my '85. I found having a small 1/4" drive ratchet and socket to be helpful on the passenger side inner mount bolts and shock tower bolts. Some tight clearances there. Having an 18" extension is also handy for a few of the outer bolts. I had a problem lining up the holes on the engine to the bolts underneath, I jacked the engine back up and moved it around with a pry bar a little bit.

well i have a 600 mile round trip comming up today, i have the engine mounts, and plan on changing them before the trip. i hope i dont run into any stupid problems. thanks for the great diy and all the great info guys! i cant wait to hear the car after the mounts are changed! i dont know why the guy i got the car from didnt do them when he changed the engine but hey, his mistakes cost him a great car. we picked it up cheap, and i have only put elbow grease in it so far, well break light headlight and just bought 2 engine mounts.

Just be really careful with the Allen screws.

my hope is that they arnt already messed up...lol if the engine was just changed then there cant ( one would think) be that much gunk in the hex heads. i was planning on buying new hex head sockets thats why i was searching for the diy first so i knew all the tools i would need first. i want it done and over with.

I just completed the engine mounts install on my 1983 300D. I went through two cans of brake cleaner and 1 can of PB Blaster before I took off the old mounts. One thing I recommend you do that I wish I did was pressure wash the engine mount areas. I also went to Harbor freight and picked up a impact 1/2" Allen socket set and a short set of Allen wrenches. Another good tool is a very small socket set. 18" breaker bar is a nice tool to have for working on the Mercedes.

well i got it done, and the 11 hour trip... terre haute, IN to kalamazoo michigan and back. thanks for the info guys. oh and i cleaned the hex heads with q-tips and seafoam. they were still full of gunk...lol and only finger tight! and the mounts were destroyed! sounds and runs like a new car!

is there a list of torque values for the w123 on the site? I've tried to look at the online shop manual (startek...) but it doesn't work with my space age 64-bit browser.

I'll be doing a few things (engine mounts included) soon and am gathering intel.

thanks!

p/s

i forgot to order a couple new bolts for the engine mounts in case one or more are stripped. What are the odds i'll need one or two (or 4?)


** nevermind ** I found .pdf version of the shop manuals. Felt like striking gold. Still not exactly certain on the mount bolts. I wanted to stop somewhere and buy a few good quality bolts to replace them or in case of a stripped head

Easy access to the inner 6mm bolt, at least on the driver's side. Haven't done the passenger side yet.
Tools:
Stub of 6mm allen wrench with no bend in it (got mine from ************** in their little motor mount tool kit)
1/4" 1/4" drive socket
1/4" wobble extension
Masking tape.

Jack up the engine.
Tape the stub of the 6mm allen into the 1/4" socket so it won't drop out as you lower it down.
Put the 1/4" socket on your wobble extension. (may work with a standard extension--I didn't try. I went with the wobble) Make the extension long enough so you can get the 1/4' ratchet on the extension way up near the top of the engine so it's easy to work with
Reach down on front side of engine mount arm close to the IP with the socket/wobble in right hand while using left hand to direct the 6mm allen into the inner bolt. (clean out the head of the bolt in advance-I use brake cleaner aerosol with a 2' extension nozzle)
Unscrew the inner bolt
Voila.

I should add that you need all this in 1/4" because a 3/8" drive 6mm allen socket is too fat. It will hit the motor mount arm and not be capable of going in to the bolt head.

All this on 84 SD

Finished the passenger side mount. I can confirm that once the air filter bracket is removed you can access the inner bolt of the mount using the tools above by feeding the long extension down between the manifold and the turbo.

Old collapsed mount on left. New lemforder mount on right.

Many other threads going on motor mounts. I have fooled with alternatives from polyurethane-filled to tried Corvette hydraulic mounts, in my quest for a smooth drive. I hear these 5 cyl diesels were smooth from the factory, and hard to imagine they could have been sold as luxury cars otherwise. So far I have verified that the mounts make a big difference. I have settled on trying quality German mounts. The cheap Made in India ones (Anchor, etc) don't seem to work well or last, and poly-filling them makes them too stiff, at least w/ a backer support needed to make the poly work.

I solved a great deal of my vibrations by changing out the motor mounts along with the tranny mount, the u joint mount, and the differential mount. Might be worth a check.