Drilling out JB Weld from exhaust bolt thread?

[Kodak]

Ok, I went ahead and shifted the engine enough for me to get proper clearance to continue drilling a straight hole. I'm getting very close to the full depth of the bolt and it seems like I'm drilling through something. The hole I've drilled is smaller than the diameter of the bolt. Should I go larger and over size the hole and tap it or stick with the size I've drilled and tap that? Pics showing the depth and diameter of the hole I've drilled

https://i.imgur.com/5BYzGx4.jpg

https://i.imgur.com/ZJvnUue.jpg

[AMK]

Step the drill size up until you just barely see the threads on the bottom side of the hole. You can then use a Dremel tool to grind a groove in the top side of the hole. Then with a punch or a small chisel type tool (you may need to grind something into shape) you may be able to "pick" the two halves out. Then clean the original threads out with a tap.

[Kodak]

Step the drill size up until you just barely see the threads on the bottom side of the hole. You can then use a Dremel tool to grind a groove in the top side of the hole. Then with a punch or a small chisel type tool (you may need to grind something into shape) you may be able to "pick" the two halves out. Then clean the original threads out with a tap.

Excellent. This is the route I will go. Appreciate everyone offering insight. Love this forum!

[Nessism]

You gotta get more in the center of the old screw. And pick up a LH drill set from Harbor Freight. As the shell of the bolt gets thinner it will spin out from drilling torque. That's the beauty of the LH bits.

[Kodak]

Well I took a stroll up **** creek today. Got a nice 7/16 hole drilled. Started tapping with a 8mm 1.25 tap, got about 5/7 of the way maybe 13/17 or 17/21, take you're fractional pick. Met some resistance, haven't tapped a bunch before so I don't know how much torque is too much for knowing when to stop and reevaluate. I know to one turn quarter turn back. Well she snapped like a dry branch. Flush break. Can't get a grip on it. Most of the tap is in there. Any thoughts? Should I buy a Walton extractor and try that??

[Alexxxx]

Had the same problem only I didn't snap the tap off. Another thing that can help is heat and cold, metal is very conductive and therefore sensitive to temperature changes. If you can't drill it out then try loosening it with alternating heat(aka blow drier) n cold. Retapping a bolt is such a pain and requires lots lots lots of patients . I feel for ya, good luck

[AMK]

Well I took a stroll up **** creek today. Got a nice 7/16 hole drilled. Started tapping with a 8mm 1.25 tap, got about 5/7 of the way maybe 13/17 or 17/21, take you're fractional pick. Met some resistance, haven't tapped a bunch before so I don't know how much torque is too much for knowing when to stop and reevaluate. I know to one turn quarter turn back. Well she snapped like a dry branch. Flush break. Can't get a grip on it. Most of the tap is in there. Any thoughts? Should I buy a Walton extractor and try that??

Did you mean 17/64 drill? Did you get all of the bolt out or did you drill and tap what you had?
Your hole was off center and if you left part of the bolt in then you were trying to tap part steel and part aluminum.
I think the part steel then came loose and jammed against the tap and broke it.
Send us a picture so we can see where you are now.

[Buffalo Bill]

I take my MIG welder and lay a fat spot weld on those broke exhaust bolts. The weld will not stick to the head and it hurts nothing. Let the first fat spot weld cool and do another right on top of the first. Repeat the process till there is enough past the head surface to grab with vice grips. The heating and cooling of doing the series of spot weld help crack the corrosion seizing the bolt too.

Oil the crap out of it with your fav penetrating oil and start working it back and forth to use the threads to grind up the crud in there. Youll soon see its getting easier and easier to move the stud...then slowly start removing it ..work back and forth and be patient.

This method might work for you.

[chuck hahn]

weld may not stick to the carbide taps. He may well be screwed now. Guess he can at least give it a try though. First I would get an old tap and try welding to it on the bench to see if it sticks rather than waste my time down on the head itself.

[gsrick]

Well I took a stroll up **** creek today. Got a nice 7/16 hole drilled. Started tapping with a 8mm 1.25 tap, got about 5/7 of the way maybe 13/17 or 17/21, take you're fractional pick. Met some resistance, haven't tapped a bunch before so I don't know how much torque is too much for knowing when to stop and reevaluate. I know to one turn quarter turn back. Well she snapped like a dry branch. Flush break. Can't get a grip on it. Most of the tap is in there. Any thoughts? Should I buy a Walton extractor and try that??

Damn that sucks, The taps are fluted so the shavings have a place to go, can you get a fine point punch on one of those and work it back out tapping it around or are the flute to deep? pACE3-997626dt.jpg.

[chuck hahn]

Or a modified pair of needle nose pliers down the flutes?? Lots of air to flush the chips out, some oil, and maybe get lucky to get the tap to move??? Snap ring pliers may also reach maybe???

[gsrick]

This tool may work. http://www.waltontools.com/products/extractr.htm

[chuck hahn]

Maybe if the taps not broke off down a hole. Think he said his broke off below the surface.

[gsrick]

I'm having trouble posting images, but if you scroll to the bottom of the page you can see it is designed to work even if it is broken down in the hole.

http://www.metalartspress.com/howtos/removing-frozen-or-broken-fasteners

[tbirdhd]

HI Kodak , hope you get it out , if you do , look in to time sert , not helicoil , I did my head and sparkplug holes . makes a much better job ,Time-Sert 1812 M8 x 1.25 Metric Thread Repair Kit on ebay #282289364765 they have all sizes that one is just to show you , where helicoil will pull out these will not ,