Broken motor mount bolts

Hello,
This is not a good day... I was playing in the snow, and I was flooring it in second, the tires caught dry pavement, and BOOOOM. I have sheared two of the motor mount screws that bolt to the block, and the third one has broken the little raised area from the block where it goes.

My first question: If I fix it and run it on just two screws, will this last?

Second question: Can I remove the inner fender, lift the engine a bit and drill out the broken screws (still in the block).

Any suggestions?

Thank you.

Mikel

Mikel said:

Hello,
This is not a good day... I was playing in the snow, and I was flooring it in second, the tires caught dry pavement, and BOOOOM. I have sheared two of the motor mount screws that bolt to the block, and the third one has broken the little raised area from the block where it goes.

My first question: If I fix it and run it on just two screws, will this last?

Second question: Can I remove the inner fender, lift the engine a bit and drill out the broken screws (still in the block).

Any suggestions?

Thank you.

Mikel

Click to expand...

There is no "inner fender" to remove on an XJ. The "inner fender" is part of the structure of the vehicle. Drilling out the broken screws, of course, is mandatory. You might want to talk to someone who can weld/braze cast iron for repairing the third "boss" that is broken off the block.

Do a search on this forum, adn you will find others who have had this problem, and maybe they have had more creative fixes.

My son in laws XJ kept shearing off the right side motor mount bolts and I found that drilling out the bolts was a pain. If you buy a "reverse rotation" drill bit it will usually walk the bolt out as it is drilling in, but the problem was getting the drill in there. I used a 90 degree angle adapter on my drill and that worked reasonably well. The second time the bolts broke off I had one bolt that wouldn't come out with the drill so I tried a different approach. I took my mig welder and CAREFULLY added a stub to the end of the sheared off bolt. The heat from the weld helped loosen the thread lock and I was able to walk the bolt right out with vise grips pinched on the welded on stub. When he broke the bolts for a third time I didn't even bother with a drill and went with the welder instead, the job was over in a fraction of the time. We finally replaced the motor mount bracket and haven't had the problem since.
I had such good luck with the mig welder on broken off bolts that I used it on the rusted and broken off bolts on my cj8 project and had only one of the broken off frame bolts that didn't come out.
Dave

i wish i had a mig welder...they are real nice for the smaller stuff.

Dave B,
If your son-in-law is beaking off motor mount bolts that frequently something is wrong. I would first look at the motor mounts. If the bushing is split or worn out it will allow the motor to twist enough to shear off the mounting bolts. If that doesn't cure the problem I would install a limiting strap, and tell him to take it easy with the right foot. Good Luck.

Woody

Thank you all.
My other question was, with one bolt missing, how long will this last? I can only replace two out of the three

I wouldn't, but it's your rig, so it's up to you. Sounds to me like they have a tendency to break with all three. If you are planning on only using two I would try and reframe from spinning donuts. Good Luck.

Woody

My son in laws rig seems to be fixed now. He swapped in new motor mounts after the second break and that didn't seem to fix it. After the third time we noticed that someone had drilled out the motor mount bracket bolt (the one that goes through the mount) with egg shaped holes for some odd reason. I had a good mounting bracket among all of my excess parts so we swapped it and he hasn't had the problem again.
I would get the broken off section fixed on the block rather than run on only two bolts.
Dave

Hello all,
The jeep is back on the road! The MIG advice was a complete success (Thanks Dave!! :cheers: ). I had a closer look at the broken area in the block, and realized that the hole (and the threads) went a bit deeper beyond the missing chunk, so I got a longer screw and I got at least 4 or 5 complete turns, I think this should last quite a while (grade 8 bolts).
One of the broken bolts I pulled out had a ~0.080" hole drilled through at a funny angle... I wonder if someone sheared the bolts and failed to pull out this one. The other funny thing is that in the broken area in the block, the threads were VERY dirty. Considering that after this happened, I had the Jeep towed home, I find this very suspicious. Have I been driving on one bolt in one side??
Anyway, thank you all for the very valuable advice!

Mikel

file a complaint with the DOT. this should be a recall and some have had fire and injury because of this problem.. The bolts are not thick enough to suport the engine load and the bracket fits poor causing failer.

http://www-odi.nhtsa.dot.gov/ivoq/

I Have 10 monts with my XJ and I found out that at the time of purchase It came just with one bolt in the right side because last week i broke the third one so I Check what was wrong An find out One clean broken bolt and two very rusty broken bolts , I am going to fix it Friday I just want to know if the three bolts are the same size, and I am going to save some money to buy the MORE bracket replacement.

This sounds like a chitty problem, and I have been lucky not to have had to deal with this issue. I did see these the other day:

http://www.mountainoffroad.com/more.htm

I know M.O.R.E makes good stuff. I wonder if these would be would make this a thing of the past.