Engine Supports

[Harry]

When I removed the engine supports, I found that there was a bolt started up from the bottom of the one on the passenger side (!).  Recall that these are mounted to the sub-frame with two each SHCS, and have a 17mm (maybe larger) bolt through the motor mounts on the engine into the supports.  This one also had a similar bolt run up through the bottom in the opposite direction of the one from above.  Weird.

Am I missing something?

Harry

[ja17]

There should be a torque plate under each mount. The bolt with rubber bushing are part of the engine torque restriction. Go to a good parts diagram and take a look at the parts you are missing. The torque plate, bolt and rubber bushing help protect the rubber motor mounts from twisting from engine torque under hard acceleration. 

[DaveB]

Seems the configuration changed from one bolt to two bolts during 230SL production (see photo from the edition B and C parts books). So I guess you have one of each.

[Harry]

Wow.  That's very interesting - thanks indeed.  Thanks for the shots from the parts book.  (I hadn't looked there yet.)  I need to re-look at the removed parts because  I don't recall the torque plates.  What is the proper installation procedure in each case?

Thanks again,
Harry

[Minerva]

Are the later engine mounts a direct replacment for the early 230 ones?
In other words can you replace the one with a separate stud and bolt with the later one with just a bolt?
Keith

[DaveB]

It is actually the two-bolt version that is later. I don't know why the change to that two bolt system, I guess it would be slightly simpler to loosen (the earlier bolt & nut system may turn without loosening).
As far as I know the mounts themselves are interchangeable across all W113, current part number 180 223 10 12 - same both sides.
Here's some advice on replacement from Joe Alexander https://www.sl113.org/forums/index.php?topic=1421.msg7227#msg7227
If your current mounts are collapsed don't drive too fast over crests because there's so little clearance between the valve cover and the hood that the motor can rise and dent the hood from beneath. I have one of those scars in mine
Hmm.. on second thoughts would the motor rise like that? Shouldn't the bolts and stop plates prevent that vertical movement? Anyway, I certainly have the dent in the hood...maybe the entire subframe has risen off its mounts to allow that contact. Or maybe someone left a tool on top of the valve cover and closed the hood - ouch.

Does anyone else have a dent from beneath in that spot - front center of the power bulge, right over the front of the valve cover?

[DaveB]

And another question Harry - does that bolt from beneath screw into the same threaded section of the engine mount that the bolt from above screws into? There barely seems enough of the female thread for both.

[Harry]

Yes, as I recall it does.  I need to do some homework this weekend then I'll report back.

[Tom in seattle]

Regarding the issue of the valve cover denting the bonnet:  I believe that you need to replace the two motor mounts as well as the transmission mount simultaneously.  This is because over time all three will compress as they age.  If you just replace the front ones and not the rear, it will tend to tilt the front up.  If you replace all 3 the motor will regain its normal tilt , up from the rear , down in front.  I test this by putting a wad of baking dough on the valve cover and lowering the bonnet.  You should have 3/4 inch clearance.  The rear trans mount is easy to replace.  The wad of dough is less expensive than repair to the bonnet and a paint job.

[DaveB]

That makes sense, I think you are right. I have very little clearance between the firewall and the back of the valve cover, suggesting the trans mount is bad.

[ja17]

A hood dent from the engine can be caused by missing "stop plates" on the sub-frame mounts also. In this case the whole engine with subframe moves up enough to dent the hood.

[UJJ]

BTW: A worn out transmission mount also gives you problems removing the valve cover as it was in my case.
When I replaced my transmission mount it was necessary to add a 3mm shim to the new mount in order to line up properly with the drive shaft flange.
My valve cover comes off easy now.

[ja17]

Many cars are missing the thick adjustment washer/shim between the transmission mount and the metal mounting plate. When missing the valve cover moves closer to the firewall.

[Sead]

Many cars are missing the thick adjustment washer/shim between the transmission mount and the metal mounting plate. When missing the valve cover moves closer to the firewall.

Is there a photo of it?

Sead

[ja17]

The shim/washer is available in different thicknesses. Look at numbers 26, 27, 28 in the diagram. One is used between the metal mounting plate and the rubber mount to adjust the height of the transmission/driveshaft/ back of engine. Seems most cars use a 5mm. Often times during repairs they are left off or used mistakenly in the wrong place.

[DaveB]

Thanks for that information.

[Harry]

Hi again.  I read the very good link and post by Joe Alexander on exactly how to replace the engine mounts but they don't address a mount with the additional bolt installed from the bottom of the mount.  How far should that bolt be run into the threaded hole?  Until the rubber doughnut is snugly fit into the plate?

Thank you,
Harry

[Benz Dr.]

From what I remember, the bottom screw has a fairly short amount of thread on it so tighten it until it stops turning and you should be good to go after that.

[ja17]

Yes as Dan says, the short threads of the bottom bolt "bottom out" and become tight. I believe there is a top side and bottom side of the torque plate also. The plate is recessed on the bottom side to accommodate the rubber buffer.

[Harry]

Thanks very much!