Hello all -- recently purchased a 1982 300D turbo, and have been reading through the archives here to exorcise the demons that plague it. Good site, and a much more mature crowd than on the other auto forums I read...

On to business: I am replacing both engine mounts and have hit a snag. The 8mm allen bolt on the pass. side mount (the one accessed through the hole underneath the car) has rounded out. I've tried tapping a 12pt, 15mm socket on to turn it out, but am having little luck.

I am thinking I could pull the entire mount leg off the block and remove it w/ the rubber mount attached, if I can raise the engine far enough. Maybe I can saw part of the mount off to gain clearance? The problem is that I can't seem to pull the mount leg off the block studs due to the rubber mount hitting the frame.

Any ideas as to how to remove this thing? I am about ready to cut the leg in half and get a new (used) one...

Thanks for any input/support.

I wouldn't cut the leg, I'd cut the mount. You're replacing the mount anyway, cut it apart. Do you have a sawzall? While building my house I developed respect and awe for the beast. Did you know that you can buy long, bimetallic hacksaw blades (like 12") and bend them in a 90 degree arc and cut with them? yes, you can. Cut through the middle, then unbolt the leg from the block and the lower half from the body. Use good penetrant on the lower 2 bolts (I like PB blaster) and CLEAN OUT THE ALLEN SOCKET THOROUGHLY before you start or you may strip these too. Especially because these face up, they collect sand and oil. You put a tool in there and you think it's fully engaged but it's not.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Petes method will work well. When you replace those allen bolts use some anti-sieze to prevent that from happening again. Also I have found that to get those bolts loose an electric impact works well. Just run it until it overheats and then put a breaker on it and it should come out.
Or course it is too late for that now. Trying to get those arms off is very rough. I know. Removed an engine from my parts car and the engine cross member was twisted up. Had to cut through the aluminum arm with a sawsall to get it out. Even with it out it was real difficult to get the remains of that arm off the block.

If you drill the head of the bolt off you should be able to jack the engine up enough to get to the bolt with some vice grips.

Several years ago I had the same problem. I believe I drilled the head of the bolt off and then removed the two upper bolts. With that and jacking up the engine, the motor mount came out. It has been many years ago and I have slept several times since then, so my memory may be a little off.

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Mike

2000 SL500 22,000 miles
1981 300CD 188,000 miles
1979 450 SEL 266,000 miles
2005 Cadillac CTS 25,000 miles

Well, it sounds like I've been luckier than some.. I was able to get the 6mm allen bolts out of the top of the mount without much hassle (lots of extensions and u-joints), as well as unbolt the leg from the block, including the bracket that goes to the turbo which holds the oil drain tube on. Of course, the bad mount has caused the tube to shear off, but I don't think it will be too tough to fix.

The sawzall sounds like it may work -- it's really a clearance issue. I can move the whole works around, but I don't know whether I'll be able to pull it out as one piece without some cutting involved. I'm a little wary of jacking the engine up any more, as I already had it up about 1.5 - 2.5 inches from where it's supposed to sit (rough guess). I could try, though.

I don't think a vise-grip would work, as the bolt is pretty recessed in the mount. Unless you mean after the 'leg' is out of the car and on the bench... that will be my plan once the time comes.

If you drill the head of the bolt off, you should be able to remove the motor mount completely. That should allow access to the remainder of the bolt.