head bolt saga

[p24-1953]

so the ongoing saga of the broken head bolts continues... soaked for a week and welded a nut on to both of them gently applied pressure and pop. broke them off flush with the block. ordered a set of reverse drill bits and slowly drilled a hole in the bolt to get a back out tool installed. it bit good. applied a little pressure and snap. broke the back out tool off flush with the block.

 

what do i do now?

 

pull the entire block and take to a machine shop? i cant remember how or ( been 8 years) does the entire front sheet metal come off in one piece on a 1940 pt105 or do i need to remove fenders, liners, grill and radiator trim all separately?

 

at a loss what to do next, other than drive it off a cliff.

[Young Ed]

How many times did you try the weld thing? If just once I would try it a few more times before giving up on it. Also I've had good luck starting with a washer welded to the stud and then welding a nut to that.

[Los_Control]

Another vote for a washer first then nut to washer.

Sounds like you're having penetration problems and not getting enough heat to solidly attach the nut.

The washer is thinner and you can get good penetration and weld it solid easier.

Then the washer gives you more surface area to weld the nut to. Is also thinner and again easier to get good penetration.

 

A main reason why welding a nut to a bolt to get it loose is not so you can put a wrench on it ..... you had that before the bolt broke.

The heat from welding on the bolt will break loose the rust ..... the more times you weld on it the hotter it gets and the better chance of it breaking free.

 

I have tried just welding a nut to the bolt and what I find is, the small center hole is filled with weld and you are finished .... the bolt never got any heat.

So the nut just pops off, never got a good weld.

So crank your welder up on high, send some heat to it .... use a larger washer so you have welding surface inside and outside the nut.

Use a grinder to remove some weld if you need to to get a wrench on it ..... the goal is to get as much heat as you can into the bolt ...... use a torch on it also if you have one .... the heat breaks the bolt loose.

[Robert Harrison]

I assume the bolt sheared off at the top of the block?  Try heating the bolt with a welding torch before you weld the washer and nut. 

 

To help if you have another one.  If I thought I had this kind of problem initially I would smack the head of the bolt with a hammer briskly several times this can help loosen the threads but you are beyond that now.  If you cant get it out by twisting the head of the bolt it is unlikely that an ez out will do it and you risk the chance of getting a hardened easy out stuck and now you cant drill that out.  I have even drilled the center of the bolt out and heated it and then carefully tried an ez out once the bolt heated it became loose.  The strength of a bolt is around the outside of the diameter.  Drilling down the center can relive some tension in some cases but whats really holding it now is not the tension in the bolt but the rust on the threads.  I've drilled the bolt out so thin that practically all there was left were the threads and I could chisel them or chisel/tap them out and I have drilled them out completely and re-taped with a larger bolt and had a new stud made to match in a machine shop then there are Heli coils too.  Your best bet is to heat the bolt first with the welding torch then weld the washer and nut now.  Once you heat the bolt with the torch before you go back to welding see if you can get the ez out out once you heat it with the torch try tapping it left and right and working it free you need to get that out if you can.  Once its heated in there expands and hopefully loosens its grip you may be able to tap it left and right and wiggle it out.  If you get the bolt to turn a little try working the bolt back and forth while applying penetrating oil. Each time you do it will go a little further.  Patience.  

[p24-1953]

Okay so over the past week I have welded a nut or bolt on to the two bolts at least a dozen times.   I even had a actual welder come by and try 3 times and it has never even  budged.   I have tried several time to drill out the bolts and I am making no progress the drill never seems to bite.   I have tried several different bit and sizes but it will not drill into the broken easy out.

 

I am about to the point of putting the head back on with out  two of the 3 center bolts.   Or weld a stud on to the broken bolt and use that to torque thr head on.

 

Talk me out of this poor decision.

[Young Ed]

Only other trick I've seen and I'm not sure it would work in that type of hole is to blast it out with an oxy acetylene setup. Saw Dad do it once in a caliper mount. The bolt melted faster than the mount. 

[Dave72dt]

Let me guess.  The nuts and bolts keep breaking off at the weld.  The "easy out" is a screw type so it needs to be backed out?  I don't know how many times it's been mentioned to weld a washer on first, then a nut to it if needed. WELD PENETRATION!  You may be able to weld a washer to the "easy out" and back it out.  it's not helping you if it's wedging the broken stud tighter.  If the broken stud has been drilled all the way through a cutting tip on a torch can burn the rest of the stud out and usually will not hurt the cast iron threads.

 

"Easyout "is a brand name.  Easy out is wishfull thinking.

[JBNeal]

Kinda sounds like it's time for the blue tip wrench...with as much welding done to that bolt, the steel is probably starting to crystallize, making it more brittle than ductile...been there, done that...with a good oxy-acetylene torch adjusted to a cutting flame, the offending bolt can be whittled out carefully.  The bolt will reach melting temperature before damage can be done to the cast iron.

 

Plug nearby water passages and cover the area to control where the slag will go.  With the O-A tip on the bolt carcass, heat until white, then hit the oxygen for less than a second to blow out the slag.  Allow the bolt to return to grey color, this allows heat to dissipate into the cast iron.  Repeat the heating-slag ejection step then allow to cool again.  Patience and attention to work area is important; if'n ya get in a hurry, you're gonna have big problems.

 

Once most of the bolt has been melted out, allow to cool to ambient, then clean cast iron threads.  Using the O-A torch can be messy and dangerous, but taking the correct precautions and keeping the flame only on the target should yield acceptable results.