engine mounts on a 300sd
 

i ordered 2 new engine mounts for my 1985 300sd
1) how far down should they compress with the weight of the engine on them?
2) if i fill them with polyurethane how much should i fill them? should i allow for compression?
3) i see guys on youtube using 3M window weld, will this work in this application? I live in the boonies n i need to get my car back up in running asap n there is only a Homedepot n a ace here in town......
4) If the 3M will work on the engine mounts , will it also work to replace the bushings on the engine shocks?

Those engine mounts are calibrated for your OM617. I'd use them as they are. The rubber in any motor mount is vulcanized in place and cannot be replaced using any home methods. The vulcanizing process is what bonds the mount to the metal parts. If you had access to vulcanizing equipment you could do that but few of us have those skills and equipment.

As far as the engine shocks - they aren't all that pricey so I'd order up a set. I'm not using them on the S-10 but it's race only and I don't mind if it's a bit "course". On a nice 300SD they're probably dead anyhow and need replaced - this is the time to do it. They'll come with new rubbers.

Dan

I'd estimate about 1/4 inch, but I never actually measured. The window weld might work, but if it's too hard you'll get unpleasant vibration.

Fill them all the way up with a Shore A 30 urethane and you'll be fine.

http://www.peachparts.com/shopforum/...t-mounts-5.jpg

he's not talking about the shocks, he's talking about the shock mount... and it's pricey... if a pullapart junkyard is not available I'd recommend a pair of fender washers to fix the mount. Roy is trying to rebuild the mounts, he wants broken parts to experiment on...

Someone had suggested to me a product called Liquid Nails, usually available at local hardware or home improvement stores. When I checked the manufacturer website, it claims to be Shore 30.

However, my impression has been that this discussion really has been around cheap motor mounts. If you bought a quality brand like Lemfoerder or Phoneix or Corteco, I would not bother with filling them.

Of course if you're like me, and bought a set of Anchors at under $4 from the Rock (for 617 NA), just for poops and giggles, then yeah....

I think I tossed my old ones or I'd donate them. I had two sets. I don't see what good filling the base of the mounts would do except making the whole deal a bit stiffer, which would not be better.

I'm not above messing with factory stuff but I don't see where you'll gain anything with this technique. My new mounts were a donation so I don't know what they cost but it wasn't much. If they fail I'll just replace them with more cheap mounts!

Dan

I'm using Lemfoerder engine mounts . I replaced them in July ones all ready with a donated pair n the driver side is shot all ready ...... Side note The kid i bought the car frome had driven the car so long with a destroyed driver side mount that it blew out the engine shock mounts rubber AND BLEW A HOLE IN THE K MEMBER ...... So ill b patching the k member with 1/8 plate steal unless someone has a better idea . N ill do something cheap for the shock mount ........the car is my salt driver n I just need it to last as best possible

The back story on the filled mounts is that when I swapped an OM617 into my 380SL I had less than optimal clearance between the engine and the subframe. Having read all the horror stories about the poor quality of currently available motor mounts, I searched for a solution that would give me insurance against a collapsed mount somewhere inconvenient (like in the middle of nowhere on one of my cross country road trips) The solution I came up with was the filled mount. Most motor mounts are just a slab of rubber between two metal mounting surfaces, so making the stock MB mount into what is essentially functionally equivalent is not a stretch.

The process showed that a stiff urethane (70) will indeed make things very harsh, but the softer Shore A 30 is essentially indistinguishable from stock.

So if someone is looking for cheap insurance or to extend the replacement interval or to be able to use cheaper mounts in the first place or has a custom application, the filled mounts are an option to consider.

I also fillers my subframe mounts to prevent those from collapsing as the clearance between my valve cover and hood is very tight as well and would result in contact.

Which product were you looking at? The regular LiquidNails adhesive is latex based. The Polyurethane Construction product showed a Shore 60 rating.

The one concern I'd have about using this kind of product for something as thick as a motor mount would be the curing. The stuff I used was a two part mix while this product relies on moisture from the air to cure. Thin applications as caulk, might be completely different from filling an inch-thick void... I just don't know.

Good question. I just looked again and I see what you mean, there are three varieties of LN but all are over Shore 30.

I will check later when I have more time, to see what I was looking at.

How far down will the mount compress with the weight of the engine on it ? I don't want to over fill it .

Just like this...

http://www.peachparts.com/shopforum/...t-mounts-5.jpg

You can't overfill it - if you try it will just run all over the ground.

You can either use dowels to provide the "holes" or you can use a 3/4" drill to drill it out later. (drill your pilot hole through the top and then expand using the 3/4" drill bit)

The reason I ask about the mount compression is because the last ones i put on were popped up like a pyramid but as soon as I let the engine down on them they colapsed down to the k member . Is that normal ?

Here you go - this is a 617 motor mount shown unloaded and loaded. This is very close to what you should expect, but be aware that the motor I have on the stand is the one out of the 380SL not the 617. The weight is a little less, around 50# or so, which means around 25# per side on each mount. I'm not sure you could measure the difference between the two engines at the mount.

http://www.peachparts.com/shopforum/...1&d=1384895981

And here's a fully collapsed mount.

http://www.peachparts.com/shopforum/...1&d=1384902052

awesome thx! yeah mine collapsed all the way down like that last pic as soon as all the weight was on them ....