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Broken Exhaust bolt in Block


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This bolt (or was it a stud?) has been broken off in the block since I bought the MJ. Up until the last couple months I didn't pay it any attention though. But after having a bad exhaust leak from the apparent torn gasket in this location, I figured I would do the right thing and try to fix it up. But my work came to a stand still with this.

 

 

Any ideas on replacing this? Its recessed about an 1/8th of an inch so I can't get anyting on it and don't really have a way to cut a slit into it. I could drill it out, but that makes me a bit nervous.

 

Thanks,

 

Sean

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good luck on that one Shawn......I had the same one snap off on both the 2.5 and the transplanted 4.0 in my MJ (and on my TJ, the rear one snapped off....). Since that's the front one, you have more room to work on it and can actually get a drill in there. Be careful not to snap off the eze-out/extractor inside it, or else you'll have to pull the head and take it to a shop to have it all milled out. BTDT.

 

Jeff

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Any reason to put a stud back in or would a bolt do just as well?

 

That stud passes into the water jacket along with the #11 head bolt that's perpendicular to it there at the front of the head. If you screw it into the head too far it will contact the head bolt shank. You can use a short bolt, 1.25" or so, but you're better off with a stud and some red loctite.

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If you try to drill and extract the bolt threads "DO NOT" drill too deep. If you break into the water jacket you will have a water leak. I went through that exercise with a remanufactured engine and ended up have to return the head for a new one. I could not seal that threaded stud for anything Loctite, Silicone, J-B Weld, it woudl leak "a lot".

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How about drilling a new hole in the center of the broken stud sliglty smaller in size and tapping some treads - you don't have to go too deep but judging by the size and lenth of the other studs you should be able to drill about half an inch w/o the fear of drilling into the water jacket.

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Hmmm...all the4.0's that I have had have never had a stud or a bolt in that location...On the last rebuild (son's MJ) I just ran a tap into it to clean the threads and then installed a 1 1/4" grade 8 bolt with a lock washer.

 

No problems so far.

 

I agree with the E-Z out warning - it is a biatch getting those things out if they break off. Take your time and go realllly slow on the pressure.

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I ended up trying to use a spiral style easy out. It broke off in the hole. :mad:

 

Luckily it had a small sliver of it protruding from the hole and I was able to use a small hammer and chisel to back it out in one piece. Then I decided to go down the HeliCoil path. I bought the kit plus a drill bit from Napa and picked up the replacement stud while I was there. I was nervous about drilling it out too far, but I don't think I did. I definitely hit the end of the bolt and there was a small pocket, which I didn't drill past. So I'm hoping that I didn't nic the water jacket or anything. I supose I won't know till its fired up. Anyway, tapped, then installed the Helicoil. Screwed the stud in with some Loc-tite and that was that.

 

 

Thanks for the tips, advice, and warnings.

 

-Sean

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