changing engine mounts

[jthierry]

Hello

is it difficult to change mounts for engine and manual gearbox on a 230 ?

thanks

[badali]

I just changed the engine mounts on my 230 SL automatic.  The drivers side was more difficult than the passenger side because of the fuel filter.  It took about one hour to change the drivers side.  The other one was about 40 minutes.  You have to raise the engine enough to get it out after the bolts are out.  There is a shim bolted to the bottom of the mount that needs about an inch of clearance to be removed.  I haven't tried to change the trans mount yet but I have it.  It looks to be simple once you are under the car...

[Iconic]

Warning Brad.
Be carful closing your hood.
If I remember correctly, if you change your engine mounts, and not the transmission mounts, the engine might be able to hit the hood because of the new position and angle of the assembly.
Am I starting bad rumors, or is my memory correct?

I changed all 3 at the same time.
So, for jthierry, let's just say you can change the mounts, but how can we tell you if it is difficult or not?
Give us something to compare it to. ie: More difficult than xxx ?
It took me a lot longer than it took badali.
I never claimed I was fast. I was just happy I could do it .... thanks to the Tech Manual, this Forum, and all of you contributors.

[badali]

That is a good point about the angle of the hood.  Mine luckily did not hit.  I have the car put away for the winter and will change the trans mount before next driving season.  The hood is open now anyway.  I guess the difficulty level depends on what you compare it to.  It was easier than working under the dash of the car for sure but more difficult than changing brakes...

[Benz Dr.]

A lot of people got the hood closing lesson from me at Willamsburg. If you let your hood slam you will evntually live to regret it one day.  :'(



  I'm not fast either, nor am I slow.   I guess that makes me half-fast. 

[ja17]

Hello jthierry,

There is a lot of information on this site about changing the motor mounts.

In general change one side at a time. Lift one side of the engine at a time.  You'll need a good 6mm allen tool.  During installation, install the hardest to get small 6mm bolt first, then the large 19mm head bolt, lastly pry the mount so that the last 6mm bolt can be installed.  Leave all bolts loose until they are all started, then tighten them up and move to the other side.

[280sl1968]

So, obvious question:

If, after changing the mounts, the engine does touch the underside of the hood, what adjustments can be made to alter the height at which the engine sits?




David

[stickandrudderman]

There is no adjustment other than making sure that you change the transmission mount at the same time and ensuring that it is properly aligned.
If you've done that and the engine is fouling the hood then you've probably got failed front sub-frame bushes.
I keep telling people to change ALL of the rubber bushes at the same time otherwise you're only getting partial benefit from any new rubber that you fit.

[ja17]

The subframe steel "stop plates" are unique to the W113 chassis cars. Their function is to provide the upper limit, to keep the upward movement of the sub-frame in check in case of sub-frame mount failure, or sudden uplift of engine and suspension. If you are having hood damage issues, first make sure that your engine aluminum side supports are correct and make sure your "stop plates" are in place. The aluminum side supports are unique to the W113 chassis also. Sedan engine side supports will  cause the engine to rest about 1" higher in the engine bay.

[andyburns]

Joe, any idea where I can get some stop plates.  I have part of the assembly, the bolts which were in the sub frame, but the plates are missing.  My local mb parts stockist tells me they are nla. 

Another question, if you have fresh engine mounts are these plates actually necessary.  Under what circumstances do they kick in?

Cheers

Andy 

[ja17]

Hello Andy,

The W113 subframe mount kits are available from Mercedes.  The plates are in these kits. The subframe mounts themselves are the same in a W113 and the W108 sedans.   However only the W113 kits have the steel "stop plates" . Unfortunately the W113 subframe mount kits are expensive ($300.00 plus). The sedan subframe mount kits are less than half the price but do not contain the stop plates. The sedans had much more hood clearance and contact was not an issue.

Find a W113 owner installing the new W113 kit and get his old "stop plates" . Otherwise you may have to buy the whole kit.

Bad subframe mounts, or having the incorrect aluminum engine side supports, or a very badly collapsed transmission mount can contribute to the close clearance problem. An abrupt or severe bump in the road can cause the subframe to rise and compress the subframe mounts.  The "stop plates" and motor mount "stop plates"  limit the travel of the subframe and engine. The stop plates under the motor mounts keep the engine in check by limiting movement from engine torque. They also  limit upward engine movement from  road conditions. Make sure these have been installed also.  Lastly ( a minor tweek) there is normally a shim between the transmission mount and the mounting plate approx. 5mm. It helps a bit to keep the drive line and engine  parallell to the chassis. This shim is often left off during repairs. \

Lastly the upper four 13mm head  mounting bolts for the subframe mounts are  slightly longer in the W113 cars since it has to also be long enough to attach the thick steel stop plates. Hopefully yours still have the longer bolts. The bolts in the sedan kits are shorter.

[garymand]

Thank you JA17,  I've wondered why the subframe mounts are so expensive now.  I replaced mine 30 years ago and just replaced the mounts AND in the process of changing all the rubber mounts.  They were all destroyed somehow and desparately needed replacement.  I found the limiting hardware and logically inferred it was thjere for a reason but wasn't sure why.  I found my driveline was still a little low and added about a 5 mm  washer under the tranny.  I assumed a  straight drive shaft was less wear on the U-ioints. You cleared up a lot of guessing.

[Benz Dr.]

The motor mount arms will say 127 SL on the bottom side. Anything else won't work.

[mnahon]

Andy, is this what you're looking for?

http://www.ebay.com/itm/MERCEDES-W111-W113-220-230-250-280-SL-SE-ENGINE-MOUNT-STOP-PLATE-AND-BOLTS-/251010896863?pt=Vintage_Car_Truck_Parts_Accessories&hash=item3a716a53df&vxp=mtr

[ja17]

Hello mnahon,

These are the motor mount stop plates and bolts. Nice photo for our documentation.  However, I think Andy is looking for the sub frame mount stop plates.

[andyburns]

Thanks both Joe and mnahon,

mnahon, these are the parts I was after.  I will probably have a crack at these on Ebay.  Joe you have thrown another curve ball.  My subframe is now back in the car.  I was totally unaware that about the subframe check system.  Can you post some pictures or diagrams to let me know exactly what you are referring to.  I thought the engine mount checks would have stopped the engine from rising and hitting the bonnet.

When I stripped my bonnet back to bare aluminum I found signs something had dented the bonnet.  It was however a  concave dent from the outside of the car so I assumed someone had put too much pressure on the bonnet during closing or dropped something on it.  I am interested if this is common.   

[andyburns]

mnahon,  just pulled the trigger on the ebay auction you listed.  Thanks for that. Will wait till they arrive, bead blast, electroplate and have myself a complete sub frame.  Another problem ticked off.  Just need JA to explain the sub frame stuff and I will be done.  Am hoping I dont have to pull it out of the car... again.

[ja17]

Hello Andy,

Here is a pic of a "stop plate" on a subframe mount.

[andyburns]

Thanks ja.  I had no idea exactly what the were for.  Thought they were just a strengthing plate to reinforce the sub frame.  You learn something new every dat   looks like I already have these in place.

[andyburns]

Ja.  Quick qustion... which is more important for bonnet protection.  1 the sub frame plate or 2 the engine mount plates.

[ja17]

Its hard to say which might be more critical. In any case, as the motor mounts and subframe mounts deteriorate the  ride quality diminishes also. Engine vibration, and road vibrations are transferred to the driver instead of being absorbed by these rubber mountings. Just make sure the stop plates are in place when it is time to change the mountings.

When "the perfect storm" of events come together and you do not have the "stop plates" you can get hood damage. The stop plates on the motor mounts also limit the "twist" or toque of the engine under acceleration. This  may prevent damage and prolong the life of the rubber motor mounts.

[andyburns]

Once again thanks JA.  I figure the 'boys' at the factory knew what they were on about and all this stuff is necessary.  Its a pain in the ass as everything I dont have delays the project by what seems and eternity.  Have to wait another week or so for the engine mount plates and then another week or so at the electroplaters before I can contemplate putting the engine back in place.  Patience is a virtue I ... but being able to drive your pagoda tomorrow is better.

[mnahon]

I'm changing the engine mounts on my car. I'm having trouble getting good leverage on the main 19 mm bolt, passenger side (LHD car) to break it loose. The exhaust manifold is quite a bit in the way. Can anyone who's done this give me a pointer on the best access point (from above, below, or wheel arch) and the best tool (socket/ratchet, closed end wrench, etc).

So far, I've tried mainly from above with a closed end wrench and with a socket/ratchet; but the bolt is on tight and there's not much room to get a good lever arm and a strong push.

Thanks...

[Jonny B]

I changed the mounts on my 280 SL a year and a half ago, or thereabouts, and don't recall doing anything unusual on the passenger side mount. I don't recall that the bolt was on really tightly though. Perhaps a combination of socket, universal joint and ratchet. That seems to be the easiest approach. I know I did not take out the exhaust manifold.

Using access from the wheel arch may also be a good alternative.

Car with A/C? Mine was not.

Check out this post - http://www.sl113.org/forums/index.php?topic=703.0 lots of detail

PS - The search function is your friend - I used the search function and the string, with quotes, "motor mount" and found the info

[mnahon]

Thanks Jonny.

I don't have A/C.

I have seen the various threads on changing engine mounts. However, I haven't come across many that go into any detail on this specific bolt. I get the impression that most others have not found this bolt to be overly tight.

I do get the impression that the suggested access is from above. Anyhow; I guess I'll just have to keep at it. I'll start by letting it soak in WD40 overnight.