Crank bolt just broke!!!
Thread Starter
Launching!
Joined: Jun 2007
Posts: 291
Likes: 0
From: Woodbury
Crank bolt just broke!!! Just finished up my cam and valve spring install. Everything was going smoothly, had her all buttoned up and when it fired up the AC belt jumped and the idler pulley in the main belt system was squeeling like crazy. Turns out the Crank pulley was not pulled on all the way back. I tore apart the front again and tried to pull the crank bolt out, because it was not tightening any more. After using a breaker bar w/a 4' cheater bar, the bolt snapped. It snapped off right where the threads start in the crank. We tried drilling it and getting an easy-out in there, but the f*cker is not moving and really don't want to break the bit in there either. I'm guessing the bolt got cross-threaded in there somehow. What would my next option be? A couple of guys have said they've heard of guys doing this and threading the end of the snout and putting a slightly bigger bolt in there while keeping the broken piece in there. I've done prolly three cam changes in my life and have removed somewhere around 20 harmonic balancers and have never run into a problem like this. Any suggestions would be greatly appreciated.
TIA guys,
Sean
TIA guys,
Sean
If you have any threads sticking out, you could try to put a nut on it and weld the inside. You might be able to turn it with a wrench. If not I would just keep drilling it one size up at a time. You could even try a reverse drill bit.
I FEEL YOUR PAIN BROTHER. I had almost the same thing happen last week when I was taking the bolt off. I had not fiished the install yet, I had only done the springs. I'm still trying to get the bolt out. I have drilled it almost as big as I can with out fuc--- up the threads. If I find something that works I'll let you know. I would love to hear how you get it out if you do as well.
Thread Starter
Launching!
Joined: Jun 2007
Posts: 291
Likes: 0
From: Woodbury
Thanks for the support bro. There's a guy on the GTO forum who says he drilled the bolt, tapped it, and put a 1" stud in it w/a nut and lots of loctite. Has worked for him for over 20K miles. I'm thinking of doing this or since the bolt broke off about 1 1/2" in the snout just tapping the smooth part of the snout and putting in another bolt, while leaving the broken piece in there...
I would tap the end of the snout. Measure ID and figure out what thread has that approximate minor diameter. Fine thread may be a better option since length is limited. You will then need to calculate a new torque value based on the thread diameter, pitch, etc. The only problem with this method is you won't have correct bolt stretch, so I would pin the damper for this reason. If you are running SLP, ATI or Powerbond, they already have a key milled in the hub and the ATI pin kit works really well.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
Launching!
Joined: Jun 2007
Posts: 291
Likes: 0
From: Woodbury
Originally Posted by vettenuts
I would tap the end of the snout. Measure ID and figure out what thread has that approximate minor diameter. Fine thread may be a better option since length is limited. You will then need to calculate a new torque value based on the thread diameter, pitch, etc. The only problem with this method is you won't have correct bolt stretch, so I would pin the damper for this reason. If you are running SLP, ATI or Powerbond, they already have a key milled in the hub and the ATI pin kit works really well.
Thanks again
Now that the damage is done you might think about some future precautions. You might want to grind a flat on one side of the old pulley bolt(you're going to throw it away anyway) and use it to chase the threads just to be sure there aren't any burrs before you install the new bolt. As the crank pulley is being pushed on you can see the pulley moving. I like to observe the relative position of the pulley to the timing cover seal as the pulley is being pushed home. When the snout of the pulley bucks up against the boss on the crankshaft the pulley stops moving and the torque value needed to turn the bolt or tool sky rockets. The pulleys should be in alignment at this point so your belt isn't going to come off. The relationship of the pulley faces to each other can be verified with a straight edge to be sure they are aligned. Before you install the pulley you might want to run the new bolt in by hand. Using your fingers to run the bolt in no snags or burrs should be felt. If the bolt hesitates as you turn it in further clean up of the threads is needed. These few precautions take only a few minutes compared to the problems a broken crank pulley bolt creates.
