806 man

Broken bolt in bell housing

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3406 E with aluminum bell housing with 2 broke motor mount bolts and a 3rd that broke off half way in.  so far I have welded a nut was able to turn it 1/6 of a turn then weld snapped . rewelded  another nut with no results so looking for some ideas such as a little heat or? 

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Try melting candle wax around it while it is hot.  Center drill all the way through and spray penetrant in the back of the threaded hole.  No matter what, that sucks!  Sorry I am not much more help.

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last one i did required removal of trans and bell housing sent it to the machine shop and had them put Cat thread inserts in... not a fun job you have there

 

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Common with high hours on a 3406, also the exhaust man bolts break off at the head.  IMO engine vibration and poor material/sizing are the issues.

A fresh nut and a good tech on a mig has worked for us as the cheapest option.

On a lesser note 460 Ford gasser engines have man bolt breakage, no issue for BB Chevy engines.

 

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That's no fun there.

As said above, removal and having a machine shop repair would be ideal. But I'm going to assume is not an option.

At the point you are at, a compact die grinder and some good carbide bits, combined with a little patience and a lot of persistence. Nibble it out with the carbide, drill out and helicoil or thread-sert.

 

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by the way it looks I'd say your screwed for using the original threads I'd drill it out and heilicoil it

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Haven't read what everyone is saying yet but do not heat it. You will make that bolt so hard you could barely drill through it and that's what you're gonna have to do. Ran into the same problem on an e model in my pete. Tried blowing through with torch but that didn't work. Had to drill it out with a little pressure from a prybar because a good hard bit wouldn't touch it after I heated it. You might be at that point now since you welded on it. Get a hole in it then easy outs is what worked for me. 

Believe I put a jack under the oil pan bolts to the block and raised it up above the frame rail where I could get to it. 

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3/4'' bolt in a blind hole. Yes I know steel and aluminum aren't a good combination to be working with. When i welded the nut on it had a nice orange color i  kept it orange as long as i could.  So today sprayed all bolts down with some high powered penetrating oil a friend dropped off. Let sit all day reapplied again late this afternoon see what happens tomorrow. Hoping to change out right side mount bolts one at a time, same issue with not wanting to break free so got butane and warmed it up a bit and was able to remove and run a tap to clean up threads and replace bolt. Tomorrow will try the butane again. this is low enough heat I can touch the aluminum and not get burned so going to roll with this plan. if not successful then yes  R&R transmission and bell housing. Thanks for ideas

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Good luck with fix. Yes warming up around bell housing will work sometimes but most times it will require removal of bell housing. A reminder from a friend once was big trucks take big bucks.

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7 hours ago, 806 man said:

3/4'' bolt in a blind hole. Yes I know steel and aluminum aren't a good combination to be working with. When i welded the nut on it had a nice orange color i  kept it orange as long as i could.  So today sprayed all bolts down with some high powered penetrating oil a friend dropped off. Let sit all day reapplied again late this afternoon see what happens tomorrow. Hoping to change out right side mount bolts one at a time, same issue with not wanting to break free so got butane and warmed it up a bit and was able to remove and run a tap to clean up threads and replace bolt. Tomorrow will try the butane again. this is low enough heat I can touch the aluminum and not get burned so going to roll with this plan. if not successful then yes  R&R transmission and bell housing. Thanks for ideas

I used a rosebud for heat on the bellhousing and seemed to help also

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Maybe left hand drill . Try centered punch and center drill . Then left hand drill in stages from small to larger till the drill almost into threads picking out bolt remains. Lots of tapping fluid if you got it ️Good luck 

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20 hours ago, 1586 Jeff said:

Are you using never/seize on reassembly?

Yes, clean up holes with tap, Gave it a BJ (my first ever) anti-seize with new elbolto's.   Today worked on the right side using 3/4'' drive set with cheater pipe not much luck until a little heat was applied no broken bolts. Easy side done next left side a real problem child.

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Hard to see what you got going in pics. You might try welding a flat washer on first or take so flat stock, drill a hole in it and weld on, then weld a nut on. Might try working it both directions too. 

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1 hour ago, redneckhippie said:

Hard to see what you got going in pics. You might try welding a flat washer on first or take so flat stock, drill a hole in it and weld on, then weld a nut on. Might try working it both directions too. 

4 bolt engine mount, Top 2 bolts broke off flush, Which is the reason for the repair. 2 bottom bolts One came out , One broke off when trying to remove. I have some of the special welding rod made to fill in the hole so hopefully I can weld a washer/ nut onto it and remove it, the top 2 with welded nuts should come out using the heating method I used on right side mount.

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I seen a guy use a carbide masonry bit to drill hard bolts. It worked.

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7 minutes ago, Diesel Doctor said:

I seen a guy use a carbide masonry bit to drill hard bolts. It worked.

I had a broken socket head cap screw in the digging brakes on my Unit cable backhoe.

 I used Artu bits, carbide insert drill bits made for drilling hardened steel.

The Artu bits cut through the hardened socket head cap screws like they were pine!!

 I have forgotten what the difference is between a masonry bit and an Artu bit, but I have heard of generic masonry bits being used.  I think that the difference might be in the fluting for chip extraction.

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And then there is one. Hopefully tomorrow the last broken bolt will turn out easy!! 

First photo is the Rat ******* that broke my lock and stole gas last night 15 minutes after I left the shop so watch out for him.

Last photo bottom left has the broken bolt 

working on this project as time always .

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Looks good. If you have been squirting much penetrating oil in the holes don't be surprised if your clutch slips until it burns off. Some of those holes do go all the way through the housing. 

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2 hours ago, Tmtbob said:

Looks good. If you have been squirting much penetrating oil in the holes don't be surprised if your clutch slips until it burns off. Some of those holes do go all the way through the housing. 

Put duct tape over the hole last night then filled the hole up with penetrating oil let it sit most of the day. Hopefully tomorrow it is easily persuaded and doesn't resist.

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Update.    Well last Friday went to town and bought a nice tight 90 degree electric drill to use on the last bolt, I couldn't center punch the broke bolt so cut a piece of 3/4'' round stock and had my 19 year old '' mechanic'' drill a small hole in the middle to help center the drill bit to the bolt. This morning I noticed an easy out in the hole so I asked what diameter the hole was he said about 1/4 '' I said lets drill a 3/8ths hole so we can use a bigger easy out so it shouldnt break as easy cause if it does break its a big issue. I had a 7.30 meeting so I left for a several hours. When I returned I asked if he drilled a bigger hole? "yes'' he replies , I say ok good I'm going to heat the area and lets try to remove the bolt then.   He replies I tried to remove the bolt and broke the easy out and it's still broke off in there. 😠 I said up to this point every bolt we have removed we had to slightly heat before they would break free and turn why would you attempt to remove the bolt without me heating up the area around the bolt first? I got nothing back. I told him we had a small problem that was manageable, now a we have big problem that could turn out to be a whole lot of work such as pull the transmission, clutch, flywheel, bell housing and possible the oil pan. If the easy out can't be removed it's time for the extracting welding rod.  Glad I have a lot hair to pull out.

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Wow that sucks!  I would consider running with 3 on one side before going through that much work!

With a good carbide cutter you should be able to grind it out.  I have found my dremel invaluable in situations like this.  The smaller carbide bits are cheaper so can be sacrificed.

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