Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Sponsored by:
Sponsored by: CARiD

Harmonic Balancer bolt broke off in crankshaft

Thread Tools
 
Search this Thread
 
Old Sep 8, 2021 | 05:33 PM
  #1  
85Iroc-Z's Avatar
Thread Starter
Supreme Member
15 Year Member
iTrader: (4)
 
Joined: Mar 2007
Posts: 1,698
Likes: 3
From: NE Pennsylvania
Car: 85 Iroc-Z
Engine: 383 TPI Procharger D1SC
Transmission: TKO600
Axle/Gears: Strange S60 3.73
Harmonic Balancer bolt broke off in crankshaft

The harmonic balancer bolt just snapped off inside of my crankshaft about half an inch past flush. Has anybody had this happen before and if so have you come up with an easy removal of it? I cant weld a nut on the end of the bolt due to it being recessed in too far, and I've heard of easy outs breaking off when trying to use them. If all else fails I may just try and drill it out and add a time-sert inside. Not sure what could really cause this to happen either. It does have a Procharger with the required extra add on crank pulley, but that has been on the car for almost 7 years now so I'm not sure how that could be the problem and just happen as of now after all of these years.
Reply
Old Sep 8, 2021 | 06:01 PM
  #2  
2knight's Avatar
Member
iTrader: (1)
 
Joined: Dec 2017
Posts: 252
Likes: 54
From: Bismarck, ND
Car: 1982 Trans Am
Engine: 5.7 ls1
Transmission: 4l60e
Axle/Gears: 3.23
Re: Harmonic Balancer bolt broke off in crankshaft

Left handed drill bits work wonders, most the time the bolt will come out while you're drilling
Reply
Old Sep 8, 2021 | 06:22 PM
  #3  
85Iroc-Z's Avatar
Thread Starter
Supreme Member
15 Year Member
iTrader: (4)
 
Joined: Mar 2007
Posts: 1,698
Likes: 3
From: NE Pennsylvania
Car: 85 Iroc-Z
Engine: 383 TPI Procharger D1SC
Transmission: TKO600
Axle/Gears: Strange S60 3.73
Re: Harmonic Balancer bolt broke off in crankshaft

I will give that a shot. Would be great if it can remove the bolt and save the threads.
Reply
Old Sep 8, 2021 | 06:58 PM
  #4  
T.L.'s Avatar
Supreme Member
25 Year Member
Liked
Loved
Community Favorite
 
Joined: Sep 1999
Posts: 3,016
Likes: 818
From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: Harmonic Balancer bolt broke off in crankshaft

If that doesn't work, you'll need to weld a bolt to the remainder of the bolt that broke, and then back it out with a wrench...

Last edited by T.L.; Sep 8, 2021 at 10:03 PM.
Reply
Old Sep 8, 2021 | 07:02 PM
  #5  
85Iroc-Z's Avatar
Thread Starter
Supreme Member
15 Year Member
iTrader: (4)
 
Joined: Mar 2007
Posts: 1,698
Likes: 3
From: NE Pennsylvania
Car: 85 Iroc-Z
Engine: 383 TPI Procharger D1SC
Transmission: TKO600
Axle/Gears: Strange S60 3.73
Re: Harmonic Balancer bolt broke off in crankshaft

I wish I could attempt that but it is broken off too far inside to be able to get a weld on it/
Reply
Old Sep 8, 2021 | 07:24 PM
  #6  
afgun's Avatar
Senior Member
20 Year Member
Liked
 
Joined: Mar 2001
Posts: 629
Likes: 10
From: New Yuck
Car: Non F-body :(
Engine: Pontiac 301
Transmission: TH350
Re: Harmonic Balancer bolt broke off in crankshaft

You might try heating the crank with a torch a little as you're using the LH drill bit, too.
Reply
Old Sep 8, 2021 | 07:24 PM
  #7  
afgun's Avatar
Senior Member
20 Year Member
Liked
 
Joined: Mar 2001
Posts: 629
Likes: 10
From: New Yuck
Car: Non F-body :(
Engine: Pontiac 301
Transmission: TH350
Re: Harmonic Balancer bolt broke off in crankshaft

You might also apply a little heat with a torch to the outside of the crank while you're using the left-handed drill bit.
Reply
Old Sep 8, 2021 | 08:29 PM
  #8  
BOOT77's Avatar
Senior Member
15 Year Member
Liked
Loved
Community Favorite
 
Joined: Dec 2007
Posts: 514
Likes: 62
From: Michigan
Re: Harmonic Balancer bolt broke off in crankshaft

Originally Posted by 85Iroc-Z
I wish I could attempt that but it is broken off too far inside to be able to get a weld on it/
It's not easy but I've done it. Just not that deep but still I have with smaller bolts than 5/8 so I think if it was me that I'd try, sometimes it's just the weld heat that really helps loosen it up. At least it's a larger bolt, you basically have to tach the center over n over n built it up w/o welding to the threads, then weld a washer and then weld a nut and hope it don't brake off or you have to start over. If I was going to attempt it, I might get some very thin wall tube to protect the threads but still your goal is to not directly weld that tube cause it will melt easy to the threads. Even then we're talking pull everything to get as much room to work. Would take a lot of patience.
Reply
Old Sep 8, 2021 | 08:58 PM
  #9  
Vader's Avatar
Moderator
25 Year Member
Liked
Loved
Community Favorite
 
Joined: Jan 2000
Posts: 19,659
Likes: 310
Re: Harmonic Balancer bolt broke off in crankshaft

A 3/8" copper tube sleeve stuck into the hole will help to prevent inadvertent welding of anything to the crank snout recess.

Whether the left-twist drill works (as it often does) or if a stud is welded to the bolt remnant, and if the threads somehow become damaged, don't sweat it. The bolt is 7/16-20, and Ed Cole was VERY clever in the selection of that. If one of those ever gets ugly, it can be re-tapped to 1/2-20 (a much more common bolt size) and a beefier 1/2-20 bolt can be used to hold everyting in place, often without even having to drill the balancer.
Reply
Old Sep 8, 2021 | 09:57 PM
  #10  
BOOT77's Avatar
Senior Member
15 Year Member
Liked
Loved
Community Favorite
 
Joined: Dec 2007
Posts: 514
Likes: 62
From: Michigan
Re: Harmonic Balancer bolt broke off in crankshaft

Yah 5/8 head not threads, just meant a larger size bolt and should have used the thread size. My local Ace hardware has thinwall brass tubes and was thinking basically the same as Vader.
Reply
Old Sep 9, 2021 | 01:20 AM
  #11  
NoEmissions84TA's Avatar
Supreme Member
5 Year Member
Liked
Loved
Community Favorite
iTrader: (1)
 
Joined: Feb 2017
Posts: 4,174
Likes: 569
From: Meriden, CT 06451
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Harmonic Balancer bolt broke off in crankshaft

Originally Posted by BOOT77
It's not easy but I've done it. Just not that deep but still I have with smaller bolts than 5/8 so I think if it was me that I'd try, sometimes it's just the weld heat that really helps loosen it up. At least it's a larger bolt, you basically have to tach the center over n over n built it up w/o welding to the threads, then weld a washer and then weld a nut and hope it don't brake off or you have to start over. If I was going to attempt it, I might get some very thin wall tube to protect the threads but still your goal is to not directly weld that tube cause it will melt easy to the threads. Even then we're talking pull everything to get as much room to work. Would take a lot of patience.
Weld does not stick to copper. Modify a piece of a copper pipe or fitting to fit inside and protect the threads if you are going to try welding to what's left of the bolt.

OOPS, Vader beat me to it.

If you do end up going to the next bolt size, like Vader also said, 1/2"-20, not 1/2"-13!!!!!

Last edited by NoEmissions84TA; Sep 9, 2021 at 01:24 AM.
Reply
Old Oct 9, 2021 | 08:47 PM
  #12  
NoEmissions84TA's Avatar
Supreme Member
5 Year Member
Liked
Loved
Community Favorite
iTrader: (1)
 
Joined: Feb 2017
Posts: 4,174
Likes: 569
From: Meriden, CT 06451
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Harmonic Balancer bolt broke off in crankshaft

Outcome???
Reply
Old Oct 9, 2021 | 09:31 PM
  #13  
Vader's Avatar
Moderator
25 Year Member
Liked
Loved
Community Favorite
 
Joined: Jan 2000
Posts: 19,659
Likes: 310
Re: Harmonic Balancer bolt broke off in crankshaft

Or, come out?
Reply
Old Oct 10, 2021 | 01:19 PM
  #14  
85Iroc-Z's Avatar
Thread Starter
Supreme Member
15 Year Member
iTrader: (4)
 
Joined: Mar 2007
Posts: 1,698
Likes: 3
From: NE Pennsylvania
Car: 85 Iroc-Z
Engine: 383 TPI Procharger D1SC
Transmission: TKO600
Axle/Gears: Strange S60 3.73
Re: Harmonic Balancer bolt broke off in crankshaft

I actually just got it out the other night. Used a left handed drill bit as recommended. Thanks for all the replies.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
tizzdizz
Tech / General Engine
40
Jun 7, 2020 07:27 PM
MikeSammy
Tech / General Engine
12
Dec 11, 2010 07:11 AM
rockmebaby
Tech / General Engine
5
May 27, 2004 09:19 AM
AcSeb
Tech / General Engine
4
Apr 8, 2002 12:45 PM
gruveb
Tech / General Engine
18
Mar 6, 2001 11:55 AM




All times are GMT -5. The time now is 12:25 PM.