W110 Motor Mounts (OM615.940 Engine) - Remove Subframe? - PeachParts Mercedes-Benz Forum

Cairo1966_W110 · #1 01-31-2021, 08:24 AM

Hello Everyone,

My motor mounts in my W110 are very collapsed, I have the parts and I will attempted to do this my self in the near future.

My question is, do I have to remove the subframe, or drop it down, in order to do this job?

I am thinking the answer is no, I can see all the bolts from the engine bay. By supporting the engine from below with a jack on a piece of wood on the oil pan, I should be able to loosen the bolts, raise the engine, and slip the old motor mounts out.

However, I started to read the MB workshop manual, and it shows that there are nuts on the bottom of the hex bolts which hold the mounts to the frame. So, that would mean underneath access is required to hold the nut to loosen the bolt? Has anyone done this job before on a W110 and can advise me?

Also, anyone have the spec of these hex bolts, in case they come out stripped. I was not able to source a supplier of these bolts. They are marked 35 in the parts diagram and 5 in the workshop manual. I have part number N914019008000 as the MB part.

See a screen grab of the manual diagram, red arrow to the nut in question. The parts diagram shows no nut. I also checked the front axel diagram, holes exist for these hex bolts, but no nut.

Anyone have a few photos of this job in progress, that would help a lot! Thanks!!

meltedpanda · #2 02-01-2021, 12:26 PM

no , just have to put a block of wood under the oil pan and carefully with a jack unload the weight of the motor from the mounts . Be careful not to raise to high and keep an eye out for any binding of hoses or such. You should be able to get to the bolts from top and bottom Its not a fun job but if you take your time it can be done. Lowering the engine back on the mounts and lining things up is the tricky part and best done with a helper to help guide engine the inch or so it will certainly shift ( ask me how I know)

Good luck

rwd4evr · #3 02-02-2021, 01:43 AM

Those should be captured nuts welded into the subframe and require no wrench from the bottom. I'd have to look but I believe they are m6 bolts.

Sent from my SM-J737A using Tapatalk

Cairo1966_W110 · #4 02-04-2021, 10:03 AM

Thanks for the advice and tips, everyone.

Engine slipping an inch, that doesn't sound good?!! Do you recommend some tie down straps or similar to hold it in place over the bolt holes while lifting? The current engine mounts are basically metal on metal now, so I am worried about shift actually.

Another question came up, I am going to do all 3 motor mounts. Which order would you do it in, transmission one first, or the two front side engine mounts, or does it even matter? It seems the transmission one is actually easier, or do I have that backwards?

Just waiting for some bolts now, hopefully get it done next weekend.

meltedpanda · #5 02-04-2021, 04:10 PM

I would do the engine first . The movement of the engine cannot really be controlled very well , it will move. I was able to get mine back in alignment by moving with a 2x4 lever arm and the jack. A helper is best because you can be under there and thread the bolts while it is wiggled into place. I was by myself so it was a bit tedious . The tranny mount is pretty straight forward as well

250 Coupe · #6 02-05-2021, 12:31 AM

I learned an interesting lesion when changing the engine mounts on my '74 F250.

Turns out it's a really good idea to chock the wheels. As I lifted the engine, the column shift linkage had just enough travel to pop it out of park. It rolled just enough to cause brown shorts before the engine dropped and the parking pawl caught and brought it to a stop.

Michael

280EZRider · #7 02-05-2021, 01:51 AM

Quote:

Originally Posted by Cairo1966_W110

Thanks for the advice and tips, everyone.

Engine slipping an inch, that doesn't sound good?!! Do you recommend some tie down straps or similar to hold it in place over the bolt holes while lifting? The current engine mounts are basically metal on metal now, so I am worried about shift actually.

Another question came up, I am going to do all 3 motor mounts. Which order would you do it in, transmission one first, or the two front side engine mounts, or does it even matter? It seems the transmission one is actually easier, or do I have that backwards?

Just waiting for some bolts now, hopefully get it done next weekend.

Actually, replacing the transmission mount first would help the engine remain in place during motor mount replacement, as it is the only mount holding the engine in place once the motor mounts are removed.

meltedpanda · #8 02-05-2021, 09:47 AM

Quote:

Originally Posted by 250 Coupe

I learned an interesting lesion when changing the engine mounts on my '74 F250.

Turns out it's a really good idea to chock the wheels. As I lifted the engine, the column shift linkage had just enough travel to pop it out of park. It rolled just enough to cause brown shorts before the engine dropped and the parking pawl caught and brought it to a stop.

Michael

good point for all of us , I NEVER get under a car unless wheels are chocked . No matter what I am doing and when I use a jack I always double support . One reason I bought a set of quick lifts . They are safe and reliable.
People die under cars because they ignore safety

250 Coupe · #9 02-05-2021, 07:11 PM

Quote:

Originally Posted by meltedpanda

good point for all of us , I NEVER get under a car unless wheels are chocked . No matter what I am doing and when I use a jack I always double support . One reason I bought a set of quick lifts . They are safe and reliable.
People die under cars because they ignore safety

I used to just chock if a wheel came off the ground but I now chock everything. In this case, the truck is high enough that you can easily slide under it on a creeper and I wasn't planning on being under it this time but even with all 4 wheels on the ground, mishaps can still bite you. I'm the guy that lays the wheel under a frame rail if I can, along with the jack stand and leaving the jack touching with a bit of pressure. I'd love a set of Quickjacks but my driveway is too sloped to make me feel safe and the garage is full of woodworking tools.

Michael

dobrodan · #10 02-06-2021, 09:57 AM

Do the fronts first, one side at a time, and everything should stay more or less in place. Do not remove both front mounts at the same time. Do the rear (transmission) last because you have to roll the car back and forth a few times to get everything properly settled before retightening the cross member (see the service manual). The front mounts should take about a half hour or so each. Use a long drift to realign the arm over the mount. Simple job.

Cairo1966_W110 · #11 03-17-2021, 03:32 PM

Thanks everyone for the tips, the job is now completed and I thought I would update and post some photos of my experience.

I started with the passenger side, loosened the bolts, nothing stripped, jacked up the engine from under the oil pan, old mount came out very easy, new one in, new bolts, and lowered, done in 20 min. The bolt holes for the 2x 8mm hex head bolts which hold the complete mount to the subframe are threaded into the subframe, so they go in really easy (that was my original question). The bolts take a 6mm drive and I used ones that are 12 mm long. Those are the only parts I didn't get original.

Drivers side was order of magnitude more complicated, it is also harder to reach. Plus, it was totally collapsed. The old one came out perfectly fine, and I am sure when I looked it was lined up, so I thought the new one will go in easy. However, when I came back with the new one to install, the engine support arm was about 1.5 cm mis-aligned. I am not sure if that happened because my "helper" leaned his full body weight on the fender or if it was because it was collapsed or exactly why this happened. Like one poster said above, this is a disaster. I also may have also caught the jack on the subframe as well as the oil pan. Front wheels were chocked with bricks, so I do not think the whole car shifted. Anyhow, to get it aligned I used another jack on the passenger side of the subframe and longer bolts, and I was somehow able to force it to align, and then once in correct position swapped out the bolts for the correct length one by one. However, I missed the "cover disk" (12 in the workshop diagram above), as you can see in the photos, drivers side all the rubber is visible of the mount. I didn't want to go back through the process, so I left it. I am not sure if it has any structural value, or is handy to keep fluids off the mount?

I can say that replacing these mounts has the biggest effect on drive feel. I had heard how much of an effect it would make, but I was really shocked. No vibrations, I think better acceleration, more smoothness overall; like a new car. Best of all, previously, the car wouldn't stay in 4th gear for long, she would pop out into neutral very often. Only on a long downhill stretch basically idling along, would we be able to cruise in 4th for any period of time. That problem is also gone, she hasn't popped out since the new mounts went in. So I guess the very collapsed motor mount was putting too much sideways pressure (or not enough) on the transmission to cause some imbalance. Any how, we are back to cruising in the fast lane and made several trips to the Red Sea about 130km from home.

PS. Didn't do the central mount on the transmission, it look's in good shape. Although I will get around to dismantling and checking it eventually.

Thanks again to everyone for their advice and comments....

meltedpanda · #12 03-17-2021, 07:27 PM

yes getting proper height for the engine will be reflective in all of the pivot points, steering knuckles as well as shifter connections better align and work as they should. Glad you got it sorted out

vox_incognita · #13 03-18-2021, 04:38 AM

Cairo, thanks for the detailed description of the procedure.

Couple of questions:
- who's the manuf. of the mounts?
-did you pre-tension the rubber buffers to "dist. a" as per manual
http://www.peachparts.com/shopforum/attachments/vintage-mercedes-forum/161223d1612099479-w110-motor-mounts-om615-940-engine-remove-subframe-w110-front-motor-mount.jpg

- if you did so, how is the feeling ?Did you use any kind of threadlocker on the lower screw?

I personally would not be worried too much about the lack of the heat/fluid shield (would just use a DIY shield out of a tire tube and a cable tie...not a beauty contest there).

meltedpanda · #14 03-18-2021, 11:39 AM

don't buy the knock offs as far as the mounts are concerned. back in the day ,I did that and they lasted less than 100 miles - defect - not sure , but went with OEM after that and had no issue for many miles

Cairo1966_W110 · #15 03-19-2021, 11:49 AM

Well, I wasn't aware that I could get original MB motor mounts. The ones I took out were just single piece, must be a very old design, as you can see what I put in matches the workshop manual exactly. I have some troubles here to order parts in general, but I found one reliable supplier in a company called Niemoeller, the price was around 70 EUR per mount. I will definitely keep my eye on them. Part number is D 22 041 (corresponds to MB part 1212230412) from their website. I ordered all the parts for this job from this company, except the bolts which come up from the bottom (MB part 1212200371) which I got from a supplier on ebay, original parts. Plus the hex bolts which I ordered from a bolt company in Scotland.

Any one have a source for OEM parts for these, which will ship internationally? If the ones I got are not OEM?

Yes, I did the pre-tension. It is not so easy to accurately measure the distance "a" as there is an offset between the measuring points, but I felt that 14 mm was too loose, so I actually went to 12 mm. And, yes, I did put a drop of blue lock-tight solution on these bolt threads before tightening. I didn't use lock-tight anywhere else. Once you install the mount, this under bolt is completely hidden, that is why I used the lock-tight, no way to check it after installation.

I would say I have done about 700-800km since the repair, everything looks good so far. Roads are very bumpy here, so I am hoping for the best. Could you be specific on how your mounts failed after 100 miles, maybe I can look out for that?