Engine mount replacement 1979 300D - PeachParts Mercedes-Benz Forum

tc art · #1 12-03-2006, 11:45 PM

Would anyone have info. on replacing engine mounts in a 1979 300D?Thanks...T.C.

SD Blue · #2 12-04-2006, 11:24 AM

When you get the new mounts, you will find that it is pretty straight forward. There is one bolt from the bottom and I believe, two from the top. (Note: you do not need to remove the "arm" portion from the side of the engine.) Also, there is a left and right difference in the mounts.

JimmyL · #3 12-04-2006, 11:26 AM

Quote:

Originally Posted by SD Blue

Also, there is a left and right difference in the mounts.

Not for a '79 300D I don't believe. One mount fits either......
Do a search and find a ton of info on this.

Also go to dieselgiant.com and look for his writeup, with pics.......(well, I just went to his site, and there doesn't appear to be a writeup on that. whoops.)
Search here..........

Jim W. · #4 12-04-2006, 01:40 PM

As Sam stated, it is pretty straightforward and if you are contemplating doing the job yourself I assume you have the expertise so you should see how to do it once you look at the mounts.

You will need a jack low enough to get under the engine, such as a floor jack, and either a block to hold the engine up or a block so the jack cannot depress. You only need a small amount of engine lift to get the mounts out and the engine will not fall out, but the jacking will take the pressure off the mounts to facilitate slipping out the old one and the new one in.

Jim W.

bgkast · #5 12-04-2006, 01:43 PM

Quote:

Originally Posted by JimmyL

Not for a '79 300D I don't believe. One mount fits either......

That is correct

vstech · #6 12-04-2006, 01:46 PM

Quote:

Originally Posted by JimmyL

Not for a '79 300D I don't believe. One mount fits either......
Do a search and find a ton of info on this.

Also go to dieselgiant.com and look for his writeup, with pics.......(well, I just went to his site, and there doesn't appear to be a writeup on that. whoops.)
Search here..........

Odd that he has a DIY video for sale, but no DIY write up...

Cephallus · #7 12-04-2006, 01:52 PM

8mm allen on the bottom, 17mm socket for the top. 10mm, iirc, to hold the heat shield on the exhaust side. The tranny mount will hold the engine 'in place' when you jack it up, so the new mounts should align pretty well...I've had best luck just starting the top bolts first, lowering until there's barely pressure on the cross member, then fitting the bottom bolts.

One thing you might want to do is spray around a little with some simple green and then rinse with a pressure nozzle...it gets pretty greasy down there!

Samuel M. Ross · #8 12-04-2006, 02:54 PM

... for I'm getting ready to do engine mounts on my in-law's W126 [1985 300SD] which has the two side engine mounts and ONLY the one other mount on the rear of the tranny.

Q - Does anyone have input at to any differences in doing this job on a W126 chassis?
Thanks,

rrgrassi · #9 12-04-2006, 05:33 PM

Make sure you clean out the allen bolts, or else risk rounding then out! Don't ask how I know!!

I replaced the left mount and both engine shocks a month ago, and had to leave the right side in until Sunday. I just got the right side finished on my 300D. I replaced the lower 8mm bolts with new ones, so I'm good to go.

Also, use a 3 or 5 pound sledge and give the bottom bolts a good whack with an 8mm allen it it. It sure helped me out, even though I had to use extractors I bought from Snap-on. I am currently working on making a "fork" to hold the engine shock shafts, and all my wrenches are too thick to slide into the notch. I'll post how I did it when I get done.

tc art · #10 12-04-2006, 09:36 PM

Thanks guys...I have a friend doing this for me...I read that I may need to replace the engine shock also. Where is this? I need to order proper motor mounts in for my engine 300D(non-turbo, OM617.912 "65" kw/88PS) and possibly a rack dampener pin afterwards to stop rough idle when hot. The engine mount on the driver's side is almost not even left! Any input...Thanks...T.C.

JimmyL · #11 12-04-2006, 09:44 PM

Quote:

Originally Posted by tc art

and possibly a rack dampener pin afterwards to stop rough idle when hot. Any input...Thanks...T.C.

You do not have a rack dampner bolt on your non-turbo 617

tc art · #12 12-05-2006, 01:24 AM

Thank you so much! I read so much about the rack dampener pin as a possible culprit. I am glad that I did not send Richard on a wild goose chase this weekend looking for one on the IP! Thank you! Are there engine shocks on her? I read advice on these sometimes needing replacement along with the mounts. I want to make sure I order what I need for replacement over weekend! Thanks again...T.C.

Samuel M. Ross · #13 12-05-2006, 09:47 AM

Quote:

Originally Posted by tc art

Thank you so much! I read so much about the rack dampener pin as a possible culprit. I am glad that I did not send Richard on a wild goose chase this weekend looking for one on the IP! Thank you! Are there engine shocks on her? I read advice on these sometimes needing replacement along with the mounts. I want to make sure I order what I need for replacement over weekend! Thanks again...T.C.

... for my Son's 1980 300D has them and [not surprising] according to several OnLine parts listings I see that the 1979 is also suppose to have them... but these same listings also show that my 1980 240D should have them as well but guess what... it doesn't. At first I thought this was because it has a relatively new engine and maybe the shock/(s) were left off or not bothered with on the new engine installation. But then I looked and compared how/where the shock was connected to the 300D's chassis and this led me to conclude that our 240D has never had engine shock(s) for the chassis does not have a place for it to mount.

I suggest you go under your car and investigate... looking for remnants of the mounts on both the engine and particularly on the chassis.

I will be working on my Son's 1980 300D [non-turbo] today for parking brake cable replacement which means I will be underneath and while there will try to get a digital photo or two to use for familiarization with how the engine shock is mounted on this car.
Regards,

tc art · #14 12-26-2006, 11:02 PM

We did replace the engine mounts. The one on the driver's side was in very bad shape! Unfortunately, this did not resolve the rough idle problem. When first started, she sounds like she's missing, after a run on the highway and coming to a stop off of an exit it is a rock and roll ride at a stop! There is a Diesel Equipment place in Greensboro that will rebuild the IP for between $600.00 to $800.00. I will have it bench tested there first if it comes to that! Any other ideas on this problem? RB did set the idle up for me also. I purchased the engine mounts from Phil at mercedesshop...great guy and a pleasure to do business with!

JimmyL · #15 12-26-2006, 11:36 PM

I think at this point, before worrying about the IP, I would do the following.
With car warmed up and idling, (poorly from what you state), I would loosen one injector line at a time, at top of injector, and see if the idle changes.[tighten injector line back before proceeding to next cy.] If you find that you loosen one injector and there is no idle change, you have a problem with that cylinder.
Now, I'm not saying you have a bad cylinder, but it isn't igniting properly. So, if you find a cylinder where there is no change, swap that injector with one from another cylinder. If the problem moves cylinders, it is bad injector. If it stays with cylinder, it could be IP or engine problem.
This is at least a decent first step......