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Discussion Starter · #1 ·
i just snapped a bolt off in the cylinder head where the upper coolant pipe bolts down. i've been trying all night to remove it and I've only made it worse. it snapped flush to the top of the head. i tried drilling it out and the drill walked off the bolt and made a hole next to it on the top. the only thing i could think of was to fill them up with liquid metal fill and try to drill and tap them tomorrow. so the question stands. how screwed am I?
 

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Just some thoughts, coz I'm not the expert here, although I can tell you it's very difficult to have a standard drill bit cut into a hardened steel bolt. In the absence of a diamond bit, I've heard tell of using a masonry bit, although they will have a tendency to "walk" so there will be a need to establish a decent centering hole. Slow drill speed, a steady light hand, and cutting oil will help. If you can get a hole cut into the broken bolt, it's time to find the correct size "easy out". Again, just some thoughts.
 

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AS I recall they're 6mm threads with 8mm heads

If you have access to a migwelder, I'd clean off the surface

and use a washer or similar with a 6mm hole in and weld the

washer to the bolt stub by welding down the hole

Then tack a nut on the washer and have a go at removing it



Hand drilling is tricky but you already know that

you need to find the exact centre then use a centrepunch to mark it and

a weeny drill to act as a pilot then progessively drill it out to say 5mm/5.5mm max

then you may be able to collapse the threaded remnant inwards with say a scriber.

I've managed to do that on occasisions but you need patience a good eye

and good drill bits



Some of those holes are blind some emerge underneath

if you damage the threads and its an emerging hole you may be able

to use a longer bolt and nut

If its blind, a helicoil is the remedy
 

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BTW

If you use the welder/washer technique dont set a low current based on the thckness

of the washer

the head will act as a heat sink and you may not get good

penetration on the bolt if you do that , so you need to up the settings and dont

worry about the washer.
 

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Some of those holes are blind some emerge underneath

if you damage the threads and its an emerging hole you may be able

to use a longer bolt and nut

If its blind, a helicoil is the remedy


This is why I asked for a picture Reg.One engine I had had a nut and bolt through the outer of the knuckle holes and worked perfectly
 

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yep so it is, I just had a wander out and looked for myself

Hopefully he has snapped an outer one as it gives him more options

and he'll have more room to work as well.



Lowlife:

One other bit of advice from someone who has

royally f*cked up manys a thing due to impatience



Take your time !

Dont attack it until you have it planned and

the best tools to hand.

Its a job that needs a slow and steady approach
 

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Glad I have a welder. Now none of my bolts will break.

First time I saw the trick was to remove a clutch pivot that snapped off a chevy. Only hard part was towing the truck to the shop. Saved a lot of headaches.
 

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Can you make a template out of say 1/2" thick steel with the bolt hole patter in the plate, such that you can use the other head bolts to secure the plate to your head, and then use the plate as a drill guide, purchase a cobalt bit to finish the job?



You could even use thinner plate and buy a drill bit bushing, weld the bushings to the thinner plate would be another approach I might try.
 

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I don't believe the broken bolt steel is very hard. A good "regular" drill should work. As already said, the important issue is to get a small drill started in the center of the broken bolt. Center punch and a small drill for the first go round. Often once a bolt breaks there is considerably less grip on the threads as the tension is now gone. Be watchful to get the drilled hole as straight into the bolt as possible, look at your alighnment several times near the beginning of the drilling. Take your time, patience is the most important ingredient, can't rush this and be successful too.
 

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Discussion Starter · #12 ·
well heres where we're at.



i snapped the bolt flush to the top of the head on the inner bolt of the left side cylinder. after swearing and cursing the sky for a few hours i tried to saw a slot into the top of the bolt. that didn't work and i actually sawed a little groove into the the flat surface of the mounting point for the coolant knuckle. the metal fill i used to hopefully fill up the groove to where it would seal failed me miserably so i drilled a new hole into the head right next to the first one and threaded it with a grade 8 bolt. i put it all back together and started to fill the system, which began to leak heavily. so after about 3 hours of trying to figure out what the hell i was going to do i pulled the knuckle off, made a gasket with high temp silicone and put it back on. 1 leak gone. after running it for a few minutes i found another leak at the pipe on this side that goes into the thermostat housing. instead of pulling it apart i tried liquid sealants. that made a huge mess and failed almost immediately. i gave it a couple hours rest while i went to my motorcycle training class and when i got home i decided to just pull it off and see why it was leaking. i used the wrong size o ring and it leaked by and fell off. i put a new o ring on, coated it with sealer to help fill in any more spots that can leak and am going to let it dry overnight before i fill the cooling system again. jesus christ i hope this is the end of it.
 

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i tried to saw a slot into the top of the bolt. that didn't work and i actually sawed a little groove into the the flat surface of the mounting point for the coolant knuckle

I suppose its too late to say

Noooooooooooooooooooooooooooooooo!

but I hope whatever you did works
 

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If the damage doesn't extend into/beyond the 'O' ring seating area you should be alright. Otherwise not good...



There should be some form of hi temp epoxy or similar that can be used to fill the divot though.
 

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[quote name='Condoski' date='21 April 2011 - 06:37 AM' timestamp='1303382229' post='63436']

"If you can get a hole cut into the broken bolt, it's time to find the correct size "easy out"."



Haha sorry, didn't see that you beat me to it.
 
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