I am new to the site, have browsed before but haven't registered. Unfortunately, a major problem has surfaced and need any ideas as to a solution, if any.

About 14 days ago, my harmonic balance bolt loosened up and balancer was hanging off the bolt. Was driving when this happened, but was able to come to a quick stop. After reinstalling with the original OEM bolt/washer and loctite everything appeared to be fine. About 6 days after re-installation, it happened again. I researched and discovered that Mitsubishi changed bolt design due to recall. Purchased new bolt/washer. It is a different design due to bolt head being larger. However, upon inspection discovered that the bolt broke off inside the crankshaft.

It sheared off about a half-inch inside the crankshaft. My dad has the extra hard drill bits (like $50 for one), and easy-outs. Once we pulled the radiator, we discovered that the bolt is sheared at an angle. Each initial attempt to drill a hole into center of bolt resulted in it sliding towards edge of bolt near threads. As you know, space is limited and difficult to get "on it".

We were able to make a small hole just off-center. While attempting to remove easy out bit broke off inside. We removed it, and attempted again. Again, broke on bolt.

Any suggestions? I have read that lifting the engine provides better access either by removing oil pan and pulling crank or simply to provide more room to center drill on bolt. Is it difficult to remove a/c condenser and bumper? Also have read pro's/con's of heating the bolt to aid its removal.

After researching online, I wanted to share my specific problem and see if any one has ideas as to a solution.

Would engine removal for better approach angle or taking to a machine shop the best and/or only choice? Typical cost for a machine shop?

I appreciate any advice you may have.

Thanks,

Brent

 

Hi Brent,
I know exactly the situation you are up against. I've been there my self, even tried the drilling with same results.

If I recall correctly (it was a long time back) what it took to get the remaining bolt/stud removed was to (elec/arc welder I think? - I'm not sure which method?)attach rod or an undersized bolt to the exposed area of the stuck bolt and then work with the extended material as best you can. Might have used rod to create /enlarge surface area and then attached extention bolt. It was not an easy task and I do recall a lot of cussing and praying, but it payed off for me that day because it would have been at least a week probably longer at the machine shop. FYI a proper weld joint is stonger than the stock material and if you use an old bolt (same material) ground down in size you will have the bolt head to wrench on. It's a matter of careful use of the space you do have as not to create another proplem because of incidental damage. I'm pretty sure this was the last option before removal of components and sending out block to macine shop for their input.
Please understand you have to make your own judgement as to the use of this method. Alot depends on the degree of removal once extension has been attached.
The reasons for the old bolt / sheared head must be factored in when making your decision to continue to try extracting as opposed to machining a new bore tap and threading and balance from a machine shop.

Regards,
motoman59