Broken Bolt
Thread Starter
Instructor
Joined: Mar 2011
Posts: 248
Likes: 10
From: Schererville IN
Broken Bolt
Car is a '65 327/365
The long bolt that secure the crankcase vent tube assembly at the rear of the block has sheared off flush w/ the top of the threaded hole. There is nothing to "grab" to remove it, so tried a bolt extractor. No luck - just can't get a good grip on the extractor due to it being down in the ventilation hole.
So I guess my only option is to try to drill it out. Does anyone know if the hole it threads into bottoms out, and how deep? Or is it a "through" hole? If so, any danger of the metal shavings ending up where I don't want them?
Any other suggestions? Thanks!
The long bolt that secure the crankcase vent tube assembly at the rear of the block has sheared off flush w/ the top of the threaded hole. There is nothing to "grab" to remove it, so tried a bolt extractor. No luck - just can't get a good grip on the extractor due to it being down in the ventilation hole.
So I guess my only option is to try to drill it out. Does anyone know if the hole it threads into bottoms out, and how deep? Or is it a "through" hole? If so, any danger of the metal shavings ending up where I don't want them?
Any other suggestions? Thanks!
Race Director
Joined: Jan 2002
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From: Close to DC
C2 of the Year Finalist - Modified 2020
I'm not sure of the answer to your first question. When you drill coat the area with some grease and also the bit, it will collect the metal shavings.
Dennis
Dennis
Melting Slicks
Joined: Jun 2006
Posts: 2,660
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From: DFW
Same thing happened to me 40 years ago... I wound up swapping the 300 HP motor for an L-79 CE crate motor!
I've wondered often about how I would have extracted the remaining bolt. I think I'd have had a sleeve made for a pilot drill. Centering the drill is the hard part. Id make the OD same as vent hole, ID to match the pilot drill. In the years between I've seen drills that are designed to cut turning left vs right to extract broken bolts. I'd try one of them with the bushing.
Good luck... I hope your fix is cheaper than mine was
Harry
I've wondered often about how I would have extracted the remaining bolt. I think I'd have had a sleeve made for a pilot drill. Centering the drill is the hard part. Id make the OD same as vent hole, ID to match the pilot drill. In the years between I've seen drills that are designed to cut turning left vs right to extract broken bolts. I'd try one of them with the bushing.
Good luck... I hope your fix is cheaper than mine was
Harry
Burning Brakes
Joined: Aug 2008
Posts: 1,174
Likes: 3
From: Mosquito Land, Manitoba, Canada
Man! Don't you just hate it when that happens. First, I would center punch the sheared bolt (try to get the center as close as possible). Put some grease on the sheared bolt to catch all the filings. Drill out the bolt with a proper sized cobalt drill bit. I find that cobalt drill bits are the strongest. After completion, re-tap the hole. GOOD LUCK.
PS: Drilling out sheared bolts is one of my worst jobs to do.
PS: Drilling out sheared bolts is one of my worst jobs to do.
Last edited by wonderful; Sep 7, 2014 at 11:54 AM.
Instructor
Joined: Jan 2008
Posts: 208
Likes: 15
From: Viera Florida
I've seen drills that are designed to cut turning left vs right to extract broken bolts. I'd try one of them with the bushing.
Erich
P.S. I was also going to put two threaded holes in the bushing so that it can be pulled out.
Racer
Joined: Oct 2012
Posts: 368
Likes: 48
From: Holland Ohio
You might try to rotate the broken end of the bolt with a sharp drift or a punch. I know this sounds weird, but call me an I'll explain it over the phone. I have had bolts broken off shear and have been able, with patience, rotate them out of the block w/o any problems. (taught to me by my neighbor, a super mechanic!)
Dennis 979-224-4245
Dennis 979-224-4245
Thread Starter
Instructor
Joined: Mar 2011
Posts: 248
Likes: 10
From: Schererville IN
Thanks for the suggestions, everyone. I think I'll try making a "bushing" to drill it out. I'm not a machinist, but do have woodworking tools. I found that a piece of wooden clothes hanger rod is exactly 1-1/4" diameter and fits snugly in the hole. So I'm going to make something w/ that and w/ a hole in the center as a drill guide.
Question: do I want to drill a 1/4" hole, then re-thread? Or do I want to drill smaller, like 7/32" then run a tap to clean the threads?
Dennis - thanks for the offer to call. If my bushing isn't turning out right I'll give you a call.
Question: do I want to drill a 1/4" hole, then re-thread? Or do I want to drill smaller, like 7/32" then run a tap to clean the threads?
Dennis - thanks for the offer to call. If my bushing isn't turning out right I'll give you a call.
Burning Brakes
Joined: Apr 1999
Posts: 1,162
Likes: 17
You might try to rotate the broken end of the bolt with a sharp drift or a punch. I know this sounds weird, but call me an I'll explain it over the phone. I have had bolts broken off shear and have been able, with patience, rotate them out of the block w/o any problems. (taught to me by my neighbor, a super mechanic!)
Dennis 979-224-4245
Dennis 979-224-4245
Try this first - it is your least risky option, and you have nothing to lose but a little time. I've backed out oil pan bolts this way with an ice pick.
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Drifting
Joined: Jun 2009
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From: Leo IN
Something to consider is getting a left handed (i.e. reverse) drill bit smaller than the bolt -- leave sufficient meat on the bolt so as to not bugger up the threads. Using tape, mark off the maximum depth that the bit should go. If you have a new bolt, the depth is easily determined by something less than the full length of the bolt.
Gently drill out the center of the bolt. In order to ensure the bit does not walk on you, use a center punch to put a divot into the bolt.
If the bolt is rusted, soak it in the appropriate penetrating oil (or 50/50 mix of acetone and ATF) overnight.
Using a bolt extractor that will reach a minimum of 1/2 the drill depth freely, insert and lightly tap with a small hammer. All you are trying to do is get a bite in the metal over a good surface area to transfer the torque necessary to remove the bolt.
Slowly and gently rotate the extractor to remove the bolt.
I have done this many, many times with success. Just take your time, drill squarely, and be patient.
After, chase the threads with a tap before replacing the bolt.
-- Joe
Gently drill out the center of the bolt. In order to ensure the bit does not walk on you, use a center punch to put a divot into the bolt.
If the bolt is rusted, soak it in the appropriate penetrating oil (or 50/50 mix of acetone and ATF) overnight.
Using a bolt extractor that will reach a minimum of 1/2 the drill depth freely, insert and lightly tap with a small hammer. All you are trying to do is get a bite in the metal over a good surface area to transfer the torque necessary to remove the bolt.
Slowly and gently rotate the extractor to remove the bolt.
I have done this many, many times with success. Just take your time, drill squarely, and be patient.
After, chase the threads with a tap before replacing the bolt.
-- Joe
Le Mans Master
Joined: Jun 2004
Posts: 9,015
Likes: 331
From: Southeast Missouri
This is a fairly common problem around farming country, probably also common anywhere old cars are involved. Here, we usually get a person with welding experience who will lay a nut on top of the broken bolt and weld the nut to the bolt. The heat from the welding operation, along with a little penetrating oil and judicious use of a wrench will usually back the broken fastener out.
I'd recommend checking around, find someone who has had some experience along this line, and give it a try. Almost always works, is a lot quicker and easier than trying to drill and tap the broken stud out. I've got one I've got to do in an intake manifold as soon as time permits.
I'd recommend checking around, find someone who has had some experience along this line, and give it a try. Almost always works, is a lot quicker and easier than trying to drill and tap the broken stud out. I've got one I've got to do in an intake manifold as soon as time permits.
Thread Starter
Instructor
Joined: Mar 2011
Posts: 248
Likes: 10
From: Schererville IN
I've already gone thru the process w/ a left hand drill bit and extractor, and per my initial post just can't get a good grip on the extractor - the end is actually below the top of the 2" deep hole. Combined w/ the fact that the bolt is in pretty tight, it hasn't budged.
One thought I had was forget the fastener and use sealant to hold it down - needs to be able to withstand the heat though. Is there such a product?
Thanks
Safety Car
Joined: Nov 2000
Posts: 4,761
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From: Clinton Township MI
Cruise-In III Veteran
Jefjak,
I feel your pain. I've been running my 327 after rebuild with this EXACT problem. Discovered this sheared flush with the block bolt AFTER the motor was in the car...this was back in '08. Well, 6 years and 25K miles later, I've been living with it by using silicone around the flange of the pipe to keep it in place. Do periodically re-seal this. That pipe 'ain't going any where when you hook it up to your aircleaner. Still functions as it should.
Yup, when the motor is pulled I will fix it correctly. It just ain't worth the hastle to fix her right in the car.
Again, I've had no issues and she functions correctly.
Good luck in your decision.
Jim
In God We Trust!
I feel your pain. I've been running my 327 after rebuild with this EXACT problem. Discovered this sheared flush with the block bolt AFTER the motor was in the car...this was back in '08. Well, 6 years and 25K miles later, I've been living with it by using silicone around the flange of the pipe to keep it in place. Do periodically re-seal this. That pipe 'ain't going any where when you hook it up to your aircleaner. Still functions as it should.
Yup, when the motor is pulled I will fix it correctly. It just ain't worth the hastle to fix her right in the car.
Again, I've had no issues and she functions correctly.
Good luck in your decision.
Jim
In God We Trust!
Pro
Joined: Feb 2009
Posts: 516
Likes: 39
This is a fairly common problem around farming country, probably also common anywhere old cars are involved. Here, we usually get a person with welding experience who will lay a nut on top of the broken bolt and weld the nut to the bolt. The heat from the welding operation, along with a little penetrating oil and judicious use of a wrench will usually back the broken fastener out.
I'd recommend checking around, find someone who has had some experience along this line, and give it a try. Almost always works, is a lot quicker and easier than trying to drill and tap the broken stud out. I've got one I've got to do in an intake manifold as soon as time permits.
I'd recommend checking around, find someone who has had some experience along this line, and give it a try. Almost always works, is a lot quicker and easier than trying to drill and tap the broken stud out. I've got one I've got to do in an intake manifold as soon as time permits.
Le Mans Master
Joined: Jun 2004
Posts: 9,015
Likes: 331
From: Southeast Missouri
Drifting
Joined: Oct 2008
Posts: 1,936
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From: Rochester Hills Michigan
It is a blind hole. I get 1.21 and 1.25 deep on '58 and '59 blocks.