Broken head bolts in Cub

[grmh2000]

Hello all, I just got a new project. I have an old 1950s Cub, i am unsure of the exact year. I was taking the old and worn sparkplugs out and as i was doing so, the last one broke off at the threads. After a few days of letting it soak and applying heat off and on, I had no success in removing the plug. Then i decided to try and remove the head and take the head to a machine shop but as i was doing that i have 2 snapped bolts now in the block. Ive talked to a few people and am led to understand that this is not that uncommon but still a royal pain. Any thoughts? Thanks

[staninlowerAL]

Yup, that pretty much sums it up. Just be thankful that you only that 2 broken head bolts. Some people have had success removing broken bolts by welding a nut on what remains in the block. I would caution against drilling and using easy out tools. If you break one off in the remains of the head bolt you are in for a real challenge. Good luck and welcome to the forum from SW Alabama. I noted that your zip code places you in SW MS. There's several forum members in your general area of SW MS and SE LA so you might be able to get some help with your project. JMHO Stan

[Bill Hudson]

#1 requirement -- infinite patience.

[NJ Farmer]

Once you remove the head I would allow ample time to let your penetrating oil of your choice allow to seep into the threads (probably for a few days) then trying with either a LARGE pair of ViseGrips or pipe wrench to remove the broken bolt.

You can also try a craftsman bolt extractor with an impact gun. Sometime the initial kick of the gun can break free the stuck bolt.

Sadly you have to use patience as stated before and don’t get frustrated losing your temper…worse things can happen!


NJ Farmer

[NJ Farmer]

I’ll also chime in on the “easy out” usage. I have not had good luck using easy-out and have broken more than a few in my lifetime. You then need to remove the hardened easy-out from the drill hole and that can be extremely difficult.

NJ Farmer

[tmays]

Pm sent

[Barnyard]

I use the Craftsman bolt extractor if enough of the bolt us sticking out. If you use an impact use a low settig and rattle it. Don't try to do it with a high setting or you may break it off deeper in the hole.

[tst]

they are not that hard to drill out and retap the hole, just make sure it is centered

[ricky racer]

The way I usually remove broken bolts is to start out with EZ outs. The best way I've found to start is by setting the head back on the engine block and place several bolts back in the head. They don't have to be tightened down, they're only there to position the head in the correct location.

Using a transfer punch that closely fits the clearance hole in the head, strike the punch to put a center punch in the exact center of the broken bolt. Remove the head and use a small diameter drill bit, like an 1/8", drill a pilot hole through the broken bolt as straight as possible. Gradually increase the drill bit size until you have a hole around half the size of the bolt diameter. It's not a bad idea to apply heat to the broken bolt if you have access to a torch.

Insert the EZ out and give it a couple of light taps with a hammer to drive it into the drilled hole. Using moderate torque to the EZ out to try to rotate the broken bolt. Don't go nuts and take a chance on snapping the EZ out off. If you fail to turn the broken bolt, remove the EZ out and step up the drill size and try a larger EZ out. If you fail to remove the broken bolt, it's probably best to drill out the broken bolt by gradually stepping up the drill size until the remainder of the broken bolt is pretty thin. At that point you can take a punch and try to collapse the remaining bolt into the hole you've drilled.

Transfer Punch Set....

[inairam]

A number of people have problems with easyouts breaking making the situation worse

Ricky outlines a nice plan to safely use easyout with a built-in plan B if they do not work. You need those center transfer punches for the best results.
Plus the shock of hitting the bolt can help loosen it.

You may also consider borrowing or investing in a set of left-handed drill bits.

[CharlieK]

good take on left handed drill bits

[Don McCombs]

Harbor Freight has a reasonably priced set of LH drill bits.

[NJ Farmer]

If you do go with the “drill out” method I HIGHLY RECOMMENDED colbalt drill bits while using oil and drill slowly in steps….3/32 then 1/8 then 5/32 etc. Go slow and straight and you will need a correct tap as well.

NJ Farmer