Broken Crank Bolt!

[robertsjm711]

2002 LS 5.3l

While installing a new oil pump I felt my stomach fall out my feet when the crank bolt snapped while installing the harmonic balancer. I was removing the bolt to measure how much more to go. I am ~1/16 from seated, and it broke at the end with multiple turns to get the bolt out after the break. At first I didn’t think it broke until I looked at the bolt. Couple questions...

1. Has anyone had this experience, and what did you do?
2. Can the bolt be removed without removing the crank at a machinist? Cost?
3. Can I remove the crank without removing heads/top end?
4. Harm with running it as is?

I just bought a rebuilt trans (still on the bench) so funds are limited more than usual, thoughts?

[Jstock85]

Yeah happened to me a couple years ago. Man I was so pissed I broke that bolt I left the project alone for several months!!! The tip of my bolt broke off way down in the nose of the crank so I tried a couple things before I ended up getting a new reman crankshaft. First I bored the bolt with HSS drill bit soaked the nose in marvel myst oil and tried a reverse bolt extractor and got no luck. I tried heating it with a torch and putting it in a deep freeze and it still wouldn't budge. Finally took it to a machinist and he said it was too deep in the crank to extract. So I just bought a new one.

Sorry I know that won't make you feel any better. Good luck!

[mongocanfly]

How deep down in the crank is the broken piece?....you've really got nothing to loose trying to drill it out and see if you can run a starter tap thru ...then a plug tap...the finish tap.....if you can get to it...hard to estimate what anyone would charge ...all you can do is ask on that one....i bet it wouldnt be the first crank bolt they had to get out...

[Tork?]

This is my worst nightmare.

[rennat_2006]

Like mentioned above how deep is it?
Have you tried getting ahold of it with needle nose or similar to see if it will spin? Sometimes losing the stretch from the head breaking off releases all tension and bolts spin right out.

Depending on the depth There is special welding rod you can get at your local welding supply that has special flux that keeps it from sticking to sides of holes, ive used it on cast iron heads with busted exh manifold bolts more than a few times that were busted off well below flush.

Public service announcement:do not ever use a ls crank bolt to seat the balancer. Threads have been pulled out of the crank or bolts busted way too many times.
A piece of all thread(18mm iirc) and a few nuts makes a super cheap balancer installer, run the AT all the way into the crank, set balancer on, then thread a nut and a washer down the all thread to pull the balancer on.

Throwing the balancer in the oven or the bbq to get a little bit of heat into it is another nifty trick.

[bigdaddy4x4]

Originally Posted by robertsjm711

2002 LS 5.3l

While installing a new oil pump I felt my stomach fall out my feet when the crank bolt snapped while installing the harmonic balancer. I was removing the bolt to measure how much more to go. I am ~1/16 from seated, and it broke at the end with multiple turns to get the bolt out after the break. At first I didn’t think it broke until I looked at the bolt. Couple questions...

1. Has anyone had this experience, and what did you do?
2. Can the bolt be removed without removing the crank at a machinist? Cost?
3. Can I remove the crank without removing heads/top end?
4. Harm with running it as is?

I just bought a rebuilt trans (still on the bench) so funds are limited more than usual, thoughts?

i say let it ride if its in far enough for the belt to line up . these ls crank bolts are really hard to remove . and the balancer I don't think it would come loose any way its, pressed on so tight. also you could weld in a washer to the hole in it. just weld to the broke bolt .not the crankshaft that would let it hold the balancer from coming off ..its worth a try

[robertsjm711]

Yes, it is way up in there. I’ll look at it tonight, but do hope it is as loose you say it could be. And yes, I know now not to use that bolt. Some things just don’t transfer from older engines...

[Overdriven]

How many threads are left on the broken bolt? My thought, if there’s enough threads still on the bolt, just shorten the bolt so it will fully seat and leave the broken piece in there. Use some red locktite so you know it won’t back out and forget about it.

Definitely heat up the balancer before installing, it’ll just slide right on.

[StingRay]

So you were using the crank bolt to install the balancer when the bolt broke? If so that's the first mistake. Never do that. Buy or make an install tool. Secondly was it a new bolt? They are torque to yield and one time use. If it was already stretched there is no telling what state it was in.

[robertsjm711]

Yes, I figured all of that out the hard way. Like I said earlier, not all procedures translate well from older engines.

I ended up grinding off enough of the end of the bolt to not bottom out, and height strength loctite it and installed it. Ran it a couple times so far and seems to work well, if I ever have to remove the balancer again I’ll replace the crankshaft.

[StingRay]

Respectfully you'd never want to pull a pressed on balancer on any engine using the crank bolt so it's not an engine generation thing at all. It's asking for trouble. Too many people have stripped out crank snouts trying that. You can get lucky or not. If you look at an LS crank bolt they actually have an hour glass mark on the head designating it as torque to yield. Don't get used to that though most torque to yield are just designated in an assy manual and not marked at all.

[robertsjm711]

Noted.