OM 617 Motor Mount center bolt won't thread back into place - PeachParts Mercedes-Benz Forum

lyricsboy · #1 08-19-2007, 03:07 PM

I've been following rg2098's excellent motor mount replacement tutorial here, and I've managed to insert the new mounts and screw in the hex bolts that mount them to the frame.

Now I've got the engine lowered most of the way back down and am attempting to refit the center bolts that hold the engine to the mounts. The passenger side went in with no trouble, but the driver side bolt is not threading into the hole on the bracket attached to the engine.

When I was removing this bolt, I unscrewed it most of the way, but it wouldn't come out simply by unscrewing. I had to grab the head with some vise-grip pliers and pull it out. I didn't have to pull too hard, and it didn't sound like anything was breaking or stripping.

Anyone have any idea why the bolt wouldn't thread back into the bracket? I've looked at the bolt's threads, and they seem fine. The mount on this side was totally wasted, so I would imagine that bolt/bracket has been under some strain.

Thanks in advance!

lietuviai · #2 08-19-2007, 03:17 PM

Try threading the bolt without the mount in place. That may tell you if the threads in the bracket are OK.

tangofox007 · #3 08-19-2007, 03:26 PM

You might need to shake the engine around a bit in order to get everything lined up. Having a helper is a good thing. Considering Newton's Third Law of Motion, the bigger she is, the better.

crashone · #4 08-19-2007, 03:28 PM

You may have to loosen the passenger side bolt alittle and try to pry/move/adjust the engine around alittle to line up. Then again if the bolt just "pulled" out you may have a stripped arm bracket. If that's the case head to the local boneyard for a replacement.

Cervan · #5 08-19-2007, 04:00 PM

Quote:

Originally Posted by crashone

You may have to loosen the passenger side bolt alittle and try to pry/move/adjust the engine around alittle to line up. Then again if the bolt just "pulled" out you may have a stripped arm bracket. If that's the case head to the local boneyard for a replacement.

you would only need one tool, cutting torches.

LUVMBDiesels · #6 08-19-2007, 04:09 PM

Quote:

Originally Posted by crashone

You may have to loosen the passenger side bolt alittle and try to pry/move/adjust the engine around alittle to line up. Then again if the bolt just "pulled" out you may have a stripped arm bracket. If that's the case head to the local boneyard for a replacement.

It took me a couple tries to get mine all lined up. Try loosening the passenger side a bit then jacking the engine back up an inch. Once you get the left side in, screw it in loosely before letting the engine back down all the way. I had good luck doing that way an getting both bolts in before lowering the engine. That way it stays lined up when it goes back down.

Stevo · #7 08-19-2007, 04:10 PM

If the threads are buggered and you cant clean them up, replacing the mount might be the way too go. That happened to a friend, he removed the old mount with a sawzall

and went to the wrecking yard for another. That was on a 240D. Hows your oil cooler hoses? Good time too replace them if there are not 100%. Sorry, i know you didn't expect to get into all that

lyricsboy · #8 08-19-2007, 04:59 PM

Awesome. Thanks for all the advice, people. If I hadn't just cleaned up I'd go out there and try these things right now. I did try a bit to move the engine around by jacking it back up a small amount (first tried threading with it fully lowered), but no luck either way.

One thing that leads me to believe that the bracket might be stripped is that the bolt will pretty much just let me push it all the way up with my socket extension, turns freely as much as I feel like trying, and then pulls/falls right back out again.

So ... all your talk of sawzalls and cutting torches has me scared. Those bracket bolts must not be too easy to free, eh?

Stevo · #9 08-19-2007, 05:20 PM

Quote:

Originally Posted by lyricsboy

Awesome. Thanks for all the advice, people. If I hadn't just cleaned up I'd go out there and try these things right now. I did try a bit to move the engine around by jacking it back up a small amount (first tried threading with it fully lowered), but no luck either way.

One thing that leads me to believe that the bracket might be stripped is that the bolt will pretty much just let me push it all the way up with my socket extension, turns freely as much as I feel like trying, and then pulls/falls right back out again.

So ... all your talk of sawzalls and cutting torches has me scared. Those bracket bolts must not be too easy to free, eh?

There are four 17mm nuts holding the arm to the block. Shouldn't be too bad.

t walgamuth · #10 08-19-2007, 08:14 PM

Quote:

Originally Posted by lyricsboy

Awesome. Thanks for all the advice, people. If I hadn't just cleaned up I'd go out there and try these things right now. I did try a bit to move the engine around by jacking it back up a small amount (first tried threading with it fully lowered), but no luck either way.

One thing that leads me to believe that the bracket might be stripped is that the bolt will pretty much just let me push it all the way up with my socket extension, turns freely as much as I feel like trying, and then pulls/falls right back out again.

So ... all your talk of sawzalls and cutting torches has me scared. Those bracket bolts must not be too easy to free, eh?

Maybe I am misunderstanding what you are saying but the threads are in the motor mount, not the arm.

the hole in the arm just allows the bolt to slip in, then you have to align it to thread into the motor mount.

Tom W

psfred · #11 08-19-2007, 08:21 PM

The later ones screw into the arm from underneath, there is just a hole in the mount. W115 OM615 are from the top, don't know about the OM616.

Peter

tangofox007 · #12 08-19-2007, 08:26 PM

Quote:

Originally Posted by t walgamuth

Maybe I am misunderstanding what you are saying but the threads are in the motor mount, not the arm.

Negative.

t walgamuth · #13 08-19-2007, 09:33 PM

Negative what?

Tom W

sailor15015 · #14 08-19-2007, 10:51 PM

The threads are in the mount arm themselves. The rubber mount that rests on the body just has a hole in it in the middle for the bolt to pass through.

I had to get one side lined up and get it within about a turn of tight then had a helper with a five foot pipe pry the engine over about an inch and put some pretty good pressure on the pipe to hold it while I got the other bolt in and tightened them both. You may just not have the rubber mount hole aligned with the threads in the mount arm.

funola · #15 08-19-2007, 11:08 PM

Yep, the threads are in the aluminum arm, with a nyloc insert. You should be able to look at the threads with a good flashlight to see if it is stripped. You have to line everything up just right and even then it is a PITA to get the allen head bolt started since there is no wiggle room there because the bolt is deeply recessed. I had a lot of problems getting the driver's side motor mount bolt in after I replaced the oil cooler lines. Couldn't get the bolt started even though the holes were lined up and the threads were not stripped or mangled. I finally took a Dremel with a cut off wheel and cut 4 slots into the tip of the bolt to make it into a "tap" and it then went in easily after that.