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Broken crank shaft bolt

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Wyatt Tankersley

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Alright so I brock my crack shaft bolt I was trying to take the bolt out after turn the engine to tdc and when I went to loosen it it snapped anyone had this happen or has any suggestions on how to get it out
 
yep. Had to pull the crank and bring it to a machine shop. Is the bolt protruding from the crank snout? Might be able to weld a nut onto it......

IMG_0731.JPG
 
hit it with some liquid wrench. Some heat would also help loosen it up but you could damage the main seal in the process so be ready to replace that.
 
Since you still have a small piece of it sticking out you could cut a slot in it for a large flat blade screw driver. Then let it soak for a while in a penetrating oil. After that heat up the crank with a torch, and try to remove it with an impact driver that has a flat blade screw driver bit.
 
1-ton said:
Since you still have a small piece of it sticking out you could cut a slot in it for a large flat blade screw driver. Then let it soak for a while in a penetrating oil. After that heat up the crank with a torch, and try to remove it with an impact driver that has a flat blade screw driver bit.
Click to expand...

It's not sticking out.
 
Instead of heating the crank shaft to make it expand and get larger than the bolt you could try freezing the bolt with some dry ice to make it shrink. Someone did that to a oil drain plug that wouldn’t budge, put some dry ice on it and it almost fell out. Maybe if you broke a chunk of dry ice off you’d be able to apply it to the bolt only.
 
The heat will break any bond between the crank and bolt from corrosion.
 
rampage said:
Instead of heating the crank shaft to make it expand and get larger than the bolt you could try freezing the bolt with some dry ice to make it shrink. Someone did that to a oil drain plug that wouldn’t budge, put some dry ice on it and it almost fell out. Maybe if you broke a chunk of dry ice off you’d be able to apply it to the bolt only.
Click to expand...
Where can I get dry ice
 
Does the bolt show a fresh clean break like the picture above? If it does the bolt is seized into the crank tight enough to break the bolt in half. That is stuck tight and the chances of getting that out with an ez-out or other type of bolt extractor is slim. Drill and re-tap are probably in your future. You may be lucky and as you were rolling the engine to TDC you over torqued the bolt to the breaking point and when you went to remove it it broke off and the bolt is free in the crank. Fingers crossed for you.
 
I had one break off on a 305 I was about to install in a truck,when I went to replace the timing chain & gears..
It broke off below flush too..:(..
But I was able to drill it close to center,and I heated the bolt up with the torch enough to get the area around the hole a bit soft and I hammered an allen wrench in the hole,and to my surprise it unscrewed fairly easy..
I hate E-Z outs and screw extractors,those nearly always snap off in the bolt on me ,unless its a big size over 1/2"..pipes are about the only things I have removed successfully with those things..

The threads in the crank snout were muckled up,("loose")--probably from a previous removal of the balancer,someone probably used an air impact to tighten the bolt when they put the balancer back on..

I only had a 1/2"x 13 tap,so I used that to re-thread the 7/16" hole in the crank..was a bit leery using coarse threads,but I had no issues with the engine after it was installed for several years..

Back in the day (before 1968 or so),the early small blocks had no balancer bolt or a hole to put one in!..They were just a light press fit,and the usual method to install one was a 5 lb sledge and a block of wood..:ooo:..(good for the thrust bearing on the mains!)..

I have seen a few fly off,one on a Corvette that did some nasty damage to the rest of the car when it flew off,but for the most part its rare to have one ever come off..
 
AV8TER said:
Does the bolt show a fresh clean break like the picture above? If it does the bolt is seized into the crank tight enough to break the bolt in half. That is stuck tight and the chances of getting that out with an ez-out or other type of bolt extractor is slim. Drill and re-tap are probably in your future. You may be lucky and as you were rolling the engine to TDC you over torqued the bolt to the breaking point and when you went to remove it it broke off and the bolt is free in the crank. Fingers crossed for you.
Click to expand...
Thank you I will try that this weekend
 
You can buy a product in a can that you can spray on parts to freeze them. Here it is https://www.autozone.com/greases-an...ase/crc-freeze-off-super-penetrant/898352_0_0

Maybe combination of at least warming the crank snout up, then hitting the bolt with the freeze compound. Can't recall what he used it on, but my Dad successfully got something un-stuck with this stuff. Probably an allen-headed pipe plug of some sort.

However, if it's cross-threaded, doubt anything short of actual effort is going to get it out. :( Still, always best to try the easiest method first I figure.
 
I used to work on Thermo King reefer units for a living,, one year TK sold a bunch of units with a really heavy crank pulley that was causing a huge amount of warranty issues because the crank bolts were snapping...I got real good at fixing broken crank bolts at 2-3 am on loaded trailers..
To the point of even welding the replacement adapter to the crank as a temporary fix until the trailer was unloaded..


I did have good luck using Cobalt reverse twist drill bits. I bought them at a tool shop that sold cutting bits for mills and lathes.. I bought 4 sizes.
I center punched the bolt,then started with a 1/4 inch then continued up in size to like 3/8.. .

Sometimes the bit will grab the snapped off bolt and spin it right out.

Drilling the bolt will release tension on the threads and you may get lucky...if it's stripped and cross threaded, then you will probably need to have a machine shop drill and tap to the next larger size. .as others have already stated..
 
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