Oh ... dear ... motor mount bolt busticated - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 12-04-2009, 03:22 PM

So the good news is, I just replaced my idle control cable and it now starts and runs great. Even though it sounded smooth, though, the engine shakes the car a little more than I'd like ... I replaced the motor mounts about a month ago (haven't driven it much since) and decided today I should give the bottom bolts a bit of a tightening, just to be sure.
And ...

Yeah, the other half is still in the frame/arm somewhere. I've done a search and it seems my options are easy out or take the whole damn motor mount arm off. Would I be wasting my time to try jamming an easy out in there? I have a bad feeling that booger isn't coming out, seeing as I clearly overtorqued the bolt in the first place.

Oh, and here's a good question for me to ask (a little late): What's the torque spec for these bolts? I was tightening by hand with a breaker bar, obviously too hard.

You know, when I said it'd be nice if I could catch a break one of these days, this is not what I meant.

And when I get that fixed, I'll have to figure out why my car is a giant massage chamber.

dieseldan44 · #2 12-04-2009, 03:35 PM

That is a bummer. Im sorry I cant offer more pointed advice, but you have my sympathy.

Left or right side?

The easy out cant hurt at this point.

JEBalles · #3 12-04-2009, 03:43 PM

Try the easy out, but replacing the support arm shouldn't too difficult. Jack up the engine a few inches and take off the four nuts and pull off the arm and put the new one on. Probably find one at a junkyard. Never tighten with a breaker bar. It's in the name. If a bolt needs to be that tight, you should be using a torque wrench.

Diesel911 · #4 12-04-2009, 04:01 PM

If it is on one of the 123 the Arm itself is not to hard to remove from the Block.

After that you can either try to get it out with and Ezie Out or just get another Arm from the Junk Yard.

Better chance for success with and Ezie Out seems to come from drilling the hole exactly down the center, using the right sized drill to match the right sized Ezie Out. After that it is the application of heat and something like PB Blaster.

I have always had trouble drilling the hole down the center; not to mention not always having the right sized drill that is sharp enough to go trough a hardened Bolt.

Also I do not like the spiral type Ezie Outs as they can expand the metal you are trying to get out.

snookwhaler · #5 12-04-2009, 04:18 PM

Quote:

Originally Posted by Diesel911

I have always had trouble drilling the hole down the center; not to mention not always having the right sized drill that is sharp enough to go trough a hardened Bolt.

Also I do not like the spiral type Ezie Outs as they can expand the metal you are trying to get out.

Same here.... Major PITA.

pawoSD · #6 12-04-2009, 04:31 PM

Stuff like that is best tightened with a torque wrench or a small 3/8" drive ratchet....preventing massive torque.

Those motor mount bolts can be a real pain.

are you able to lift up the motor and remove the motor mount? If part of the stud is still sticking out of the arm you might be able to grab it with a vice grips and remove it.

Otherwise I'd go for removing the arm itself like has been suggested.

Biodiesel300TD · #7 12-04-2009, 04:48 PM

If yours is the driver's side arm I have a motor mount arm out of a 77 300D that shoud work if you want to replace it. Let me know.

NoSparkNeeded · #8 12-04-2009, 04:52 PM

LOL, I thought I made that word up. I use it all the time. My friends and family kid me about it

. Great minds think alike I guess.

pawoSD · #9 12-04-2009, 05:26 PM

Quote:

Originally Posted by NoSparkNeeded

LOL, I thought I made that word up. I use it all the time. My friends and family kid me about it

. Great minds think alike I guess.

It is an excellent word.

Right up there with Explodified.

Or.....Rupturized

Brian Carlton · #10 12-04-2009, 06:07 PM

Quote:

Originally Posted by BodhiBenz1987

Yeah, the other half is still in the frame/arm somewhere. I've done a search and it seems my options are easy out or take the whole damn motor mount arm off.

The remaining piece of the cap screw is threaded into the arm and has no tension on it at the moment. Accordingly, if the threads were reasonably clean prior to assembly, there is a small clearance between the threads of the cap screw and the threads in the arm. Therefore, it will take minimal torque to remove this last portion of screw. It might be possible to rotate it with your fingers or with a pair of needle-nose pliers.

If, however, the screw was forced into some old, unclean threads...........all bets are off with regard to the aforementioned recommendation.

I've broken many 3/8-16 SHCS in the shop when I didn't use the torque wrench..........the remaining piece always backs right out with little effort. The components are new, however.

brownrice78 · #11 12-04-2009, 06:15 PM

Those motor mount bolts are real soft and easily drilled if need be. Don't ask me how I know

BodhiBenz1987 · #12 12-04-2009, 07:13 PM

Thanks, all. I'll give it a try with needle-nose pliers, then an Easy Out. Biodiesel300TD ... I'll let you know if I need the arm ... that would be great, it is indeed the driver's side and I think a 77 would be the same. Hopefully it'll come out for me and I can just pop a new bolt in there and (carefully) torque it on. Lesson learned.

Junkman · #13 12-04-2009, 07:35 PM

You may as well use a left hand drill bit when drilling for the easy out. Sometimes the bit will extract the bolt. Take your time to center the bit. Use a center punch & a couple of drill bits to step up to the correct drill size.

layback40 · #14 12-04-2009, 07:47 PM

Hi,
If you heat the mount arm it will expand more than the remaining bit of bolt as aluminum expands more than steel. It may make it a little easier to remove, looking at the head of the bolt, it looks like you have had a problem with corrosion, the remainder of the bolt may be seized in. Heat on the aluminum will help. I use never seize or copper kote when steel bolts go into aluminum. The lock washer should stop it coming loose.

BodhiBenz1987 · #15 12-04-2009, 07:52 PM

Quote:

Originally Posted by layback40

Hi,
If you heat the mount arm it will expand more than the remaining bit of bolt as aluminum expands more than steel. It may make it a little easier to remove, looking at the head of the bolt, it looks like you have had a problem with corrosion, the remainder of the bolt may be seized in. Heat on the aluminum will help. I use never seize or copper kote when steel bolts go into aluminum. The lock washer should stop it coming loose.

The good news is that it shouldn't be corroded in there ... I changed the mounts about a month ago, and at that point the bolts came out without much effort. I was just being obsessive when I decided to tighten them again today, and applied too much force. Still, the heat might be helpful to get the bolt end out if it's in there tight. Gonna have to find my torch.