Stripped motor mount bolt - HELP needed ASAP - PeachParts Mercedes-Benz Forum

Chad300tdt · #1 01-30-2008, 05:01 PM

I am in the throws of changing my oil cooler lines, motor mounts and engine shocks & mounts. The car is up on the jack stands, I'm ready to jack up the motor via the oil pan. I went to loosen the 8mm hex bolt under the left mount and saw it was already rounded out a bit. I sprayed it with PB blast and let it sit for a while after tapping on it. I tried to apply some heat for about 20 seconds and tried turning it which finished rounding out the hex bolt.

How should I go about removing this bolt now? It looks like tight quarters for whatever the solution is. The bolt head is accessed through a hole in the crossmember under the mount.

harrygrey382 · #2 01-30-2008, 05:14 PM

can you get a drill in there? LAST resort generally seems to be drilling...

harrygrey382 · #3 01-30-2008, 05:16 PM

or you could nock in a sacrificial oversize torx bit

Chad300tdt · #4 01-30-2008, 05:22 PM

There's room for a drill, I guess I'll have to go get a screw extractor set.

I don't have any torx bits to sacrifice.

Is there supposed to be only one bolt to remove from under the mounts, or is there one on the passenger side too? I didn't see one, but want to make sure before I start jacking up the motor.

Chad300tdt · #5 01-30-2008, 05:31 PM

Thanks for the tips. I looked at Sears.com for a screw extractor set. Will I need to drill the bolt first, or will the extractor bite the hex head insert?

DeliveryValve · #6 01-30-2008, 05:46 PM

Although I haven't tried to remove the bolt using this method while in the car but a last resort is to jack up the motor and let the the rubber mount rip apart and maybe you might have room get to it.

I've removed motors without removing the bottom bolt and let the mounts rip apart.

tgingrich · #7 01-30-2008, 06:00 PM

I like this way too - then you can unbolt the mount arm from the engine block and really get some elbow room on your workbench instead of pinned under the car.

123Guy · #8 01-30-2008, 05:18 PM

The other possibility is an "easy out", you can pick up one that will work (or get a whole set - this isn't the only time in your life that you'l screw up a hex bolt) at most any hardware or Harbor Freight or ....

blackestate · #9 01-30-2008, 05:43 PM

right size extractor should tap in lightly and secure itself when loosening the bolt. Looks like a strange drill bit.

toomany MBZ · #10 01-30-2008, 07:08 PM

If you are dealing with and allen type bolt, an easy out is threaded backward, so as you "loosen" it bites into the damaged hole.
If you're dealing with a hex head bolt, a "bolt grip" tool is helpful.
Good luck.

validius · #11 01-30-2008, 10:55 PM

Sears carries some great tools called 'bolt outs'. they are like reverse easy outs that grip the outside if the screw instead of the inside.

Chad300tdt · #12 01-30-2008, 11:15 PM

Does anyone have an opinion about this drill bit? I am considering getting this one to drill the bolts out. Will this last for drilling out two bolts? Is there a better bit to buy and where from?

http://www.sears.com/shc/s/p_10153_12605_00966062000P?vName=Tools&cName=PowerToolAccessories&sName=Drill%20Bits&psid=FROOGLE01&sid=IDx20070921x00003a

validius,

I saw the "bolt outs" while at sears today picking up the DRILL-OUT Power Extractor set. I don't think they will fit through the hole in the crossmember to get to the bolts. The extractors aren't long enough to reach the bottom of the hex insert and the bolts are so tight, I think the extractor might break off in them anyway. I think my best bet is to just drill them out carefully.

DAR2KMR2 · #13 01-31-2008, 12:54 AM

I wouldn't mess with any of the bolt extractors .... none of that stuff works all that well in this situation. Just get a drill bit the size of the outer diameter of the screw and drill the head right off the bolt. That will free the mount from the arm. Then raise the engine until the arm extends above the mount and unscrew the bolt from the arm by hand .... since there is no more tension on the bolt it will just twist off by hand. If you don't have enough clearance just remove the arm and then unscrew the bolt. It's fairly simple ..... I have had to do it more than once to correct previous shoddy work by others.

David Roseman
Long Beach, Ca

PatricdeBoer · #14 01-31-2008, 01:10 AM

I had a similar thing happen to me on my 300sd. I just jacked up the engine and unbolted the whole arm. It is held on by 4 bolts and they are all pretty easy to get at.

JimmyL · #15 01-31-2008, 01:26 AM

Well, when I had some frontend work done on my wagon in my early MB days, the guy called and said I needed engine mounts and that he wouldn't charge much to put them on. Sounded fine to me.
I picked up the car and he said one of the mount bolts was stripped so he pounded a torx head or similar socket into the allen bolt and removed it that way. Cool.
Then I was horrified to find out that he put that same bolt back in.....

I will have to deal with this some day......