Adventure Driven Talk

Tech Questions and How-To Articles => Mitsubishi Related => Topic started by: Canyonero on June 10, 2017, 04:22:22 PM

Title: Broken crank bolt
Post by: Canyonero on June 10, 2017, 04:22:22 PM
Hey y'all. My brother just called me and said his crank bolt snapped. For you guys that have dealt with this before, can you post up how you went about fixing the issue? He's going to sign up on the forum, and I'll direct him to this thread. Thanks in advance.
Title: Re: Broken crank bolt
Post by: Justice on June 11, 2017, 08:19:02 AM
1st option is to drill it out. Right angle drill, remove radiator to get as strait shot at it. may want to remove condenser and front body panel too. once enough material is removed, re tap. There's some type of special kit available that I've seen others use with success. Others can help more here.

if drilling fails the bolt can be popped or exploded out with an Ox-etalyne torch. I used this method after I broke a drill bit off in the bolt and could no longer drill it. the bolt vaporizes if done right and quickly since the bolt is a different type of hardened steel it will melt before the crankshaft metal (but you must do this quickly,  then run a tap. The repair I did lasted years (2002) and I think this engine is still in service in an AZ crew rig possibly. All related parts should be replaced after bolt removed. Harmonic ballancer, crank gear, updated bolt etc.

People don't like to use this method, but if all else fails its worth a try before you go pulling the engine to replace the crankshaft.
Title: Re: Broken crank bolt
Post by: JohnnyBfromPeoria on June 11, 2017, 09:38:22 AM
I tried to drill into the broken bolt and use a left handed easy-out to unscrew the bolt; this did not work, and like Justice, I was left with a broken-off easy-out stuck in the bolt. I was able to drill a bigger hole, through the easy-out and the crank bolt, completely through the end of the crank bolt inside the crankshaft snout. Then Motero came over with some wonder tools of his and used tiny hack saw blades (I was not here to see this) to saw the bolt from the center of this hole towards the outside edge and section the bolt into several parts that then were able to just be pulled out.
That left me with bad threads, naturally, but there's a sturdy solution to the issue. A company called Time-Sert that makes a kit just for this purpose. You get the proper sized drill bit, a tap, several threaded inserts and a tool to seat the threaded insert. Once you drill out the hole to get rid of the old threads, you tap new threads for the insert, then the insert gets screwed in and the special seating tool locks the insert into place. Then you use the stock replacement bolt to put everything back together like nothing happened. I've had my bolt out and back in a couple of times since then for a timing belt replacement and a front main seal replacement, and there hasn't been a problem with the insert holding the 130+ lbs of torque. Fantastic product.
The hard part is getting the old bolt out, but with perseverance, you'll get it eventually. I hadn't heard of the way Justice described; that sounds extreme and I'm not experienced enough to try that! Just don't be afraid that you'll damage the threads, it's gonna happen, most likely, and the kit will take care of fixing it.

John B.
Title: Re: Broken crank bolt
Post by: hike2fish on June 10, 2019, 04:49:44 AM
Time-sert saved my ass! I did this repair a few years ago on my 95 SR, still have the kit if anyone is in this pickle!