Stripped thread for header attachment

Excuse my poor terminology, but I removed the headers and noticed that the thread is completely gone on one of the holes. Actually the hole is almost completely gone. Any advice? Does anyone know if I can drill a bit deeper and rethread? How much meat do I have under there?

 

Also, is it necessary to replace the gaskets between the header and cylinder? The old ones look to be in alright shape.

 

Found this

http://xjbikes.com/Forums/viewtopic/t=29356.html

that answers the gasket question

 

Had one on #3 exhaust of my XS11 that needed repair. Mine was kind of tight next to the frame. Since I was having tires replaced, I elected to have a local shop install a Time-Sert. Problem was that it had wollered out the hole enough that a standard insert was very loose. They were able to go up to a size that would house a standard size Time-Sert for that stud and basically put one inside another and it worked out great.

 

Looks like someone tried to drill out the old stud with too large of a drill bit. Haul to a local shop and have them extract the old stud. Worse comes to worse, you need to pull the head and take it to a specialist to have the stud disintegrated. Repairing the hole is easy, a Time-sert or Helicoil with a new stud would work fine.

 

Just tried attaching the headers again, and it looks like 3 of the remaining holes are also a bit stripped. Can't get the bolts to grip any thread in there. Fired her up though with them as attached as possible and they only leak a little

I was going to ride this a little bit before the season ends in a couple months, and then over the winter rebuild the whole engine. Might have to start that job early and then fix the exhaust mounts while I'm at it.

 

If the stud is out (difficult to be sure from pictures) a decent welder could re-create the boss. Should be able to do it in place.

For the others, simply install a thread repair insert of your preference.

 

It's recommended that you replace the gaskets anytime you remove the header pipes. I've reused them with no problem. But then again, I'm a cheap old fart.

 

Another tip: Once fixed, don't use bolts. Use studs, with nuts.

You screw studs in once, and leave them. Any tightening, loosening, subsequent removals and replacements, etc., don't involve unscrewing them from the head.

Thus greatly reducing the risk of a "repeat."

 

I actually snapped one of mine off trying to tighten one side
I chose to not fix it
but get the one remaining side as tight as possible
and since the rest is held with the exhaust parts
it has been fine
does it bother me.. yeah I feel dumb
but at the same time it just proves how soft the metal is
as for exhaust o-ring replacement
it is a must
I know Fitz will frown on this one
but it works for me
so I am leaving it
maybe someday I will fix it
but in the long term, there are more things to worry about
for me
aka important things like valves, brakes and tires
you know the safety things
oh and every other vehicle on the road trying to kill me

 

With some models the 'stud' system could make it difficult to get the engine out of the frame.

 

I over the years have become an expert at drilling out broken bolts and studs because of being a mechanic in the food industry and what I would do is grind off the remaining bit of stud so that it is flat, center punch it in the exact center, get a good quality left hand cobalt drill bit with an extractor and drill it STRAIGHT.
If the bit wanders off center then you need to stop because the head is soft and the hole will go way off to one side.
If you are good and get it drilled through (or at least deep into it) then try the extractor. be gentle because extractors are hardened and near impossible to drill out if they brake.
You can also keep increasing the drill size until you get to the thread and run a tap into the hole to clean out the remaining stud thread.
If all else fails then take it to a machine shop that has a Wire EDM and they will fry it out for you. (I had to EDM out a broke stud from a turbo for my Turbo Seca cuz the guy before me broke a tap in the hole doing just what I have explained to you)
Good luck

 

All VERY good methods, except for the wire EDM part. That can't work. Sinker, drop head, conventional, disintegrator, whatever they call it, now that, is the EDM that you need from your machine shop.

 

when you go in a machine shop with your problem, don't mention EDM or whatever. just ask the man if he will do it and how much it will cost.
doesn't matter if he uses a cnc edm a laser from space or a butter knife, just so it's done. when you pick it up you can ask how he did it.
probably on a old Bridgeport made in the 20's, they've been taking out broken bolts since they invented bolts

 

LOL!

True on the Bridgeports. I've been doing it for decades.

 

Unfortunately I'm not having any luck. My metal drill bits aren't making a dent in it at all. I haven't tried a left hand drill bit yet, would that make a difference? I have cleaned up the other 7 attachment points so they are all in great working order and got some studs instead of screws. Still not sure about what to do with the one broken one though. Would a left hand cobalt bit make any difference? Seems like the old screw that is stuck in there is a very hard metal.

 

Hi Jens

I had some success drilling out a stud using Dewalt 'Extreme' brand drill bits. The average drills you can buy are pretty poor an only good for wood and plastic. The Dewalt are quite expensive but give a satisfying spiral of swarf. Use at low speed..

Good luck

J

 

What a100 said, spend the dosh for a top shelf drill bit.

 

Left handed are nice only because the sometimes grabs the broken stud or bolt and spins it out for you.
I would get a good quality "high speed steel" HSS, or a cobalt bit.
They are more expensive but they are very hard and will drill through most steel you can put them on. (unless the steel you want to drill is hardened)
Run small bits at high speed and keep pouring the cutting oil to it.
Cutting oil is the trick. Even get somebody to spray the oil while you drill. FLOOD IT.

 

Cutting oil, cutting oil, and cutting oil.... oh, did I mention cutting oil?