Engine mounting bolt - any tricks? - PeachParts Mercedes-Benz Forum

tbomachines · #1 08-09-2010, 09:35 PM

I've had to put my engine swap on hold for a few days due to the engine mounting bolt. I am speaking of the 8mm allen bolt with round sides that holds the aluminum mounting bracket to the mounts. This bolt was STUCK and already stripped, thanks to a PO. To get the engine out I just tore the mount in half (rubber came apart easily) but still had to get the bolt out.

To get the remaining piece of the motor mount off, I took an angle grinder and cut it in half. So what I have now is the engine mounting bracket (took it off the engine block) along with the bolt still stuck in it. I have done everything I know to do with stuck bolts...soaked it in PB for a while, didn't work. Applied copious amounts of heat while smashing on the thing in a vice, didn't work. Pipe wrench, didn't work. Vice grips, didn't work. Are there any specific tricks that anyone knows about that might get this thing loose? I would have thought that the heat would work since the bracket is aluminum and screw is steel, but no luck after lots of sweating and swearing.

layback40 · #2 08-09-2010, 09:59 PM

Sounds like you may be trying too hard. Put the shaft of the bolt in the vice nice & tight. Find a piece of suitable hollow steel tube (about 6' long) or RHS that fits over the alloy bracket to act as an extension. Heat the end of the bracket, not the bolt shaft. Pull the extension to undo. If the bolt doesnt come loose, the bracket will break (unlikely) or the bolt shaft will break & you will need to get another bracket from a junk yard.

aaa · #3 08-09-2010, 10:12 PM

Just grab the bracket/mount arm from the other engine, forget the bolt.

Diesel911 · #4 08-09-2010, 10:20 PM

One of our Members Drilled completly through the Arm and used a longer bolt with a nut on the top to when he installed it; instead of threading and tapping the hole.
I suppose the Hole wa slightly oversized to allow for the OD of the Bolt.

But, he did that while the are was still on the Engine and the Arm was in the car.

You got a good bite on it with a Pip Wrench and it would not work I am guessing it is not coming out.

tbomachines · #5 08-09-2010, 10:49 PM

I wish I did have an extra to take off the other car, but the PO of that one took it along with the engine. Layback, I tried that though without as large of a cheater bar. The problem with it is that nothing would stick in far enough to get enough leverage, it kept slipping out...its sort of a weird curved pyramidal shape.

I think I am going to try and grind a few corners into the bolt for the pipe wrench to catch and try it again with heat, after that maybe welding a big piece of steel to get some leverage. Why they had to make the thing round is beyond me

I guess the last resort will be drilling it out, but using it with a nut gives me a bit of concern for the strength of the arm. It is only aluminum and that will change the way in which force is directed through the piece (i.e. not the way it was designed). That would serve as a decent last resort though-- thank you for the suggestion.

charmalu · #6 08-09-2010, 11:46 PM

That isn`t exactly some soft aluminium, must be an alloy.

The first time I pulled my engine, the 8mm allen bolt stripped out. tried to use valve lapping compound to get the bit to grab the inside the bolt.

I thought I was really up the creek w/o a paddle now. how am i going to get this engine out with the arm still bolted to the frame. at the time I thought the 8mm bolt held it to the body.

I read of heating up the bolt and dripping wax on it, and it would wick down through the threads. I drilled a small hole on the top of the arm and tried from that end. didn`t have any good results.

So I had this bright idea

of using my Sawzall. so Iam standing on my head trying to cut off the arm. that is one tough piece of aluminium.

So as Diesel911 sugested of drilling down through the arm and adding a through bolt with a nut on top should`s hurt the strength of the arm.

After I went through this work, then realized my folly. should have just removed the 2 little bolts

. then worried about it after the eng was out.

I still have that arm and mount laying around here somewhere bolted together.

I agree as above, just get one at the JY.

Charlie

aaa · #7 08-09-2010, 11:28 PM

I ended up doing drilling straight thru like Diesel911 said. No amount of heat helped, and I think it may have wrenched off more than once. Btw, what side is it?

layback40 · #8 08-09-2010, 11:34 PM

You could try sliding a big nut onto the end of the bolt shaft & welding it there if you need something to grip on.
Heating the housing and dumping it into water to cool it may loosen it as well. We do that at times to get bolts on dozer cutting edges to loosen.
The main thing is not to heat the bolt, that just makes it tighter.