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Broken bolts


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Ideally, this post will help those who are suffering from the broken bolt in the block syndrome.

 

My daughter came back from college on Friday complaining that the engine in her XJ had been making a 'roaring' noise. After a lot of poking around we discovered that the engine mounts needed replacement. Little did I know that the passenger-side engine mount had not only failed but it had broken all three bolts that held the mount bracket to the engine block.

 

To add insult to injury the bolts that had broken off were behind the damn frame rail, and difficult to get to without pulling the engine. The bolts were also grade 8 hardened steel, so I was really at a loss as to what I was gonna do.

 

Making a long story short, I got 5 different size drill bits, starting with 1/32 and going up to 7/16. I also purchased a set of square 'easy-outs' from Sears (NEVER use the round spiral ones - they snap!). I also borrowed a right angle air drill.

 

First I used a center punch to get the exact center of the broken bolts. Then, using the slowest speed possible and copious amounts of PB Blaster, I drilled a hole starting with the smallest bit and as each was completed (meaning I reached the back of the broken bolt) I went to the next size bit until I got to the 7/16. (I gauged the depth by pulling a good bolt from the driver's side and measuring it, then marked the drill bits for that depth with a sharpie marker). In some cases I had to shorten the bits to allow the drill and bit to fit the space. Once the hole was complete I took a MAPP gas torch and heated the block around the broken bolt, then GENTLY tapped the square easy-out into the hole and, using the smallest cresent wrench I have I gently tried to turn the broken stud.

 

If it seemed I had to apply more then a gentle pressue on the easy out I would gently try to turn it the other way...rocking it back and forth to ensure I did not break the easy-out off in the hole.

 

It took me 6 hours to remove the three bolts, but I was able to get them out without jimmying up the existing threads or pulling the engine from the Jeep. After the block cooled I re-installed the bracket, this time using locking washers under the bolts to avoid this problem in the future.

 

All-in-all, the old saying of 'easy does it' applies in these situations. I found that the hardest thing was keeping my patience while I gently drilled and removed these PITA's. Hopefully you will never have to, but if you have a broken bolt in the block you might want to try this method, especially if they are hardened bolts.

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