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JeepinJordan 04-15-2012 01:21 AM

Oil pan bolt broke...
In the final stages of my RMS replacement(96 zj 4.0), as I put on the oil pan and tightened the final bolts, one spun spun spun and broke inside the block. Its a corner rear driver side bolt.

Can I use a screw extractor without removing the oil pan, i dont really want to go through that hell again. And where could I pick up a replacement bolt?


ClimbStuff 04-15-2012 04:27 AM

I would remove the pan, clean out the crank case, tape it up, then drill out the center and try to use an extractor. If the extractor doesn't work, you could use a left handed tap, tap the inside of the broken bolt and drive a left handed bolt inside it, and it should help you back it out. Just be careful not to damage the threads or crack the block. Best thing to do is go to full studs. ARP probably makes a set.

JeepinJordan 04-15-2012 06:23 AM

Will I need a new pan gasket?

ClimbStuff 04-15-2012 07:22 AM

Any time you torque down a gasket, and then remove it, you should replace it. You might be able to get away w/o it if you use a healty dose of RTV, and allow it to cure before adding oil. I personally, would replace it.

wgirvine 04-15-2012 09:28 AM


Originally Posted by JeepinJordan (Post 13412550)
.. one spun spun spun and broke inside the block...

And thus the importance of using a torque wrench.

Ok, you broke a bolt off inside the block. IF you have room for the drill motor, I see no reason to remove the oil pan. Metal chips from the drilling can't get inside the pan. Now for the hard part... drilling out the bolt.

You use a bolt smaller than the bolt size; you don't want to get into the threads. I have had good luck using a left-hand carbide drill bit Carbide is very hard, but brittle. Don't bend it! You won't find this at a hardware store; look in a machine supply house ( The problem comes from the fact that bolts never break off leaving a smooth, flat surface. It's always at some angle, which makes drilling straight down the center of the bolt. Go slowly and watch what you are doing. Wear safety glasses; the chips will fall into your face....

Most of the time, the left-hand drill bit will, at some point, grab the bolt and spin it right out. If it does, you're golden. If not, well... now it's time to reach for the screw extractor. The problem is the typical extractor really sucks; they expand the bolt which is exactly what you don't want. Try to find an extractor with a shoulder. It will screw into the bolt only so far, then usually pulls the bolts out.

You can also try the idea of the left-hand tap. They grab the drilled bolt, but don't expand them like a screw extractor.

Obviously, this is going to take some time. Be patient, and do it right. Oh, as for where to buy a new bolt... why not the dealer? And just a thought, if you broke one bolt, you may have over-tightened all of them. I would replace all of the oil pan bolts.

Good luck.

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