| 1997 S500 DIY engine mounts - the real story
Sorry about the previous post- not quite sure what happened.[:D]
Anyway, I got up the courage to finally replace my mounts after reading some posts on the site. In particular I like to thank Inetd and his post which can be found here http://benzworld.org/forums/forums/thread-view.asp?tid=1188205&posts=2&hl=engine+mounts
A few notes of my own that I'd like to add to the procedure.
As Inetd says, the mounts have two attach points- the bottom of the mount attaches to the sub frame with two 13mm bolts and the top to an engine carrier which is basically an arm that is bolted to the engine and then attaches to the mount with one 17mm bolt. The clearance is ridiculously tight- but not impossible. It's all in the technique.
First, remove the fan shroud by removing the small retaining clip at the top of the shroud. Rotate the shroud to the right and it will fall away. Just leave it hanging on the fan-your removing it so the fan which raises with the engine will not jam into the top of the shroud.
Get under the car and remove the bottom engine compartment panel. This should expose the 13mm bolts (two per side. Remove these. Now raise the engine about 2 inches(60mm). I used a floor jack with a Styrofoam pad placed under the oil pan. Be VERY careful not to raise the engine too high or you'll damage the accelerator and speed control linkage.
Now you have the clearance to get your hands and a 17mm box-end wrench on the top bolt. For the right mount(as you look into the engine compartment) I was able to get a hand and said wrench on the top of the bolt and loosen it. Then get under the car and withdraw the bolt. (feet towards the rear- I found that my hands worked better when I slid way back to wards the rear and worked with my hands above my head). Once the bolt has been withdrawn, the mount should be loose. Remove the top cover plate and work it out. There's a power steering line in the way so you'll have to finesse the mount out. I rotated it 90 degrees and tipped it up on it's side and slid it out between the forks of the engine carrier. It almost looks like it can't be done but stick with it and it'll come out.
The other mount (left as looked at from the front of the engine compartment) has to be done from completely underneath the car. In this instance, your head to wards the rear of the car works better. You can get your right hand and wrench onto the top part of the mount by sticking your hand through a hole to the right of the mount. (it'll make sense once your under there.) This mount should fall away pretty easily once the bolt is removed.
To install the mounts, it's pretty much the reverse procedure. I used a little blue locktite on the 17mm bolts only as they were the only ones that showed evidence of locktite in the past. The other item to remember is to start the 17mm top bolt first. This may require lowering the engine slightly so the holes line up. Once the top 17mm bolts are started, thread the 13mm bottom bolts but do not tighten. If you lowered the engine to start the top bolts, raise it back up to give your hands the clearance they need to tighten the top bolts. This could take a while because you can only turn the bolt about 10 degrees before having to reposition the wrench. Ensure the key way on the mount and the engine carrier are aligned. Once the tops are tight you can slowly lower the engine and tighten the lower mounts. Replace the bottom engine compartment panel and the fan shroud and pat your self on the back for a job well done!
This procedure took about five hours to complete- three of which was spent staring at the engine trying to figure out how I was going to access the the top bolts and then how to start the top bolts when the holes didn't line up (lowering the engine brings the hole in line). Also using a screwdriver to move the mount around so you can line up the two bottom bolts helps.
Hopefully with this slightly winded description, you'll be able to shave a few hours off. I'm confident that I could do the job in about 2 hours if I had to do it again.
Good luck all!
Paul | 
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