Broken bolt

[tbird175]

While removing my poppet valve my 78 175 HP Blackmax I broke off the bolt at the front of the cover. It is sticking out of the block about 3/16" but not enough to get a good grip with vice grip pliers due to its location. I have used penetrating oil for three days and still can not put enough pressure on the stub to break it loose. It is a 5/16 ss bolt. Can some of you engine gurus give me some suggestions. I feel that heating the aluminum boss where the bolt is on the block would help but I am concerned with the possility of damaging the block. Any help will be appreciated.

 

[bill j]

Re: Broken bolt

I would center punch it and drill it out very carefully to a smaller size. then try to tap it back to the correct size. or helicoil it back to the correct size. You might need to pull the power head to line up straight. The bottom line is that sucks! just be carefull!!

 

[tbird175]

Re: Broken bolt

It will be very difficult to center punch and drill with the condition fo the stub sticking out. I am reluctant to try grinding it flat because of the possible damage to boss. Can anyone describe a good way to heat the aluminum boss around the bolt without damaging it?

 

[380voltz]

Re: Broken bolt

no problem
your best option in this case, with nothing to grab is to use a welder
very carefully make a small spot on the remainder of the bolt.
spot again over it
spot again to build to form a little stump you can grab from
let it cool down
if u beleive in God now is the time to say a small prayer
then
a) get a gripper ... grap the stump and turn
or
b) if u feel exotic weld a 100mm rod perpendicular to the bolt and turn slowly

careful not to create a molten pool when u spot or u will fuse everything
if u cant weld, take it to someone who can
it shld come out without damaging the aluminium dont worry
Good luck !!

 

[thefairlaneman]

Re: Broken bolt

A picture would help greatly..It sounds like a real bear . I do know that heat and aluminum is a very tricky thing.

 

[tbird175]

Re: Broken bolt

I will post a picture tomorrow, can not do it today.

 

[GKT]

Re: Broken bolt

sears sells these little things by craftsman that go on the bolt...theyre spirled on the inside and you put a 9/16 socket over the end of the little grabber and turn..as you turn it it spirals down the bolt and grips on it. i just removed 3 broken bolts yesterday with those things. sorry, i dont know what theyre called

 

[tbird175]

Re: Broken bolt

I attempted to drill a hole in the broken bolt with no success. The ss is very hard, maybe I can find a better drill bit. Can anyone tell me if there is a safe way to heat the aluminum boss without damaging it?

 

[380voltz]

Re: Broken bolt

I attempted to drill a hole in the broken bolt with no success. The ss is very hard, maybe I can find a better drill bit. Can anyone tell me if there is a safe way to heat the aluminum boss without damaging it?

each attempt u try will lessen the chance of you getting that bolt out.

... u wish to heat aluminium safely .. OK .. well u take an oxy aceteleyne torch and light it. u will waste your time and chances.whats the point u hv nothing to grip to right? heating al is tricky only because it wont turn red when hot. if u over do it will melt without warning
in anycase its only the ss u hv to heat to get the bolt out.

... u wish a better drill bit ... OK .. well buy a cobalt bit ... it will drill SS like butter ...but u wont the bolt out of the head ... actually you will screw it in tighter and risk tearing the al thread

use the welding method I explained with stick, mig or tig ... its the safest in your situation.
its what pros do everyday.

these diy store solutions are for fixing barbie dolls in airconditioned situations
tbird175 ... u cant imagine the power of the dark side of the force ...

 

[littleredrooster]

Re: Broken bolt

I have been a a welder for over 45 yrs.If you have 3/16 of an inch still,get a little 6 inch pipe wrench.Make sure it is a good one.You will be able too get it out.The teth on the wrench have too be new.I have got manny out this way. GOOD LUCK!

 

[tbird175]

Re: Broken bolt

I will try the pipe wrench. I am not sure if that or the welding of an extension to the bolt will work. The 5/16" bolt broke before breaking loose, It did turn slightly before breaking. Based on this I don't know if exerting more pressure on the same stuck bolt will help. I believe that it is the seizing of the ss threads with the aluminum threads that is causing the problem not interference from pressure between the threads and the bolt may break again with more pressure being applied. If heating, which should be applied to the aluminum boss to make it expand from the bolt is out due to the danger of damaging the block, it may be best to drill and re-tap if necessary. One other option might be applying CO2 to the bolt to attempt to shrink it. Any thoughts on these ideas?

 

[sorensonrg]

Re: Broken bolt

I was drilling out a broken bolt (no corrosion though, just lots of stupidity went in to breaking it) and started with a well centered punch then a very small bit (yes you need a good set, not expensive but meant for metal) and step up slowly in size so the center stays put (too big a jump and you may wander off center). Take your time and lub the bit. I was planning to drill out and rethread but decided to tap in a Trox socket that fit snug (harbor freight is good for these) and it backed right out. Made my day after ruining it by breaking the bolt. Welding is sure fire if you know how but this works for those who don't have a machine to weld with. If it's corroded in, good luck. Heli-coils here we come.

 

[huntsman.45]

Re: Broken bolt

I have applied a little heat directly to the remain portion of the bolt. You only need to heat it just a little bit, but hot enough to melt pariffin wax, allow the wax to cool then do a plumber's turn (tightening a little) then try to remove. Wax works pretty good on broken bolts.

 

[chum1]

Re: Broken bolt

grind the bolt flat, center punch and start step drilling carefully. use this style helicoil kit and use one size smaller drill bit then what they suggest on the kit. dont waste your time and money on super duper extractors, and mighty tighty grip vise&dice grips has been my experience.