Stripped Bolt on Buderus Boiler

Boston34

I have a Buderus G215 boiler, oil. The tech who cleaned the boiler stripped the bolt holding the door on. Can they drill and tap a new hole either wider or deeper? Will this cause the boiler to prematurely fail down the road?

mercedes

Heli-coil will work perfectly for you and it will be the same bolt size and have the same strength as the original bolt. They use these heli coil kits on cars cylinder head bolts. Try a good automotive supply store. here is the web site
http://www.helicoil.in/helicoil.htm

STEVEusaPA

When you say stripped, you don't mean the bolt broke off, correct?
Are you sure the bolt isn't damaged and the hole is ok? So they can get a new bolt?
Pretty hard to wreck the threads in the hole, I would think, unless the tech was using a monster wrench to tighten it up.
They could drill/tap a slightly bigger size, but they better be careful, unless they want to buy you a new boiler.
If done right, it will be fine.

STEVEusaPA

mercedes said:

Heli-coil will work perfectly for you and it will be the same bolt size and have the same strength as the original bolt. They use these heli coil kits on cars cylinder head bolts. Try a good automotive supply store. here is the web site
http://www.helicoil.in/helicoil.htm

Looks interesting, never saw that before.

Shalom

I've only used Helicoils once. Back when I worked as a locksmith, we had an HPC-1200 key machine. The vice jaw that held the key blank was on a steel stud with a humongous wing nut to clamp it down, but the other end of the stud was screwed into an aluminum (or other soft metal) carrier. Over the years, as things loosened up and we tightened that nut harder and harder to keep the blank still, eventually the stud ripped out of the carrier.

I bought a Helicoil kit from a nearby auto parts place. It came with a tap, but we had to supply the drill (21/64" if I remember correctly), Drilled and tapped the hole, screwed the thing in (it looks like a spring) broke off the tang at the bottom, screwed the stud back in, and it's been holding for almost 30 years now. Although they don't use that machine much these days.

Fred

The Helicoil works great. I've used them before. It's hard to find them locally though. At least in my part of the woods.

HomerJSmith

Boston34, you aren't very clear on your description of what your problem is.

A bolt is a male threaded piece you can hold in your hand that screws into a nut or female threaded receiver. A stud is a threaded male piece that is welded to a base in which a nut can be attached or a piece that is threaded on both ends and screw into female threaded receiver and can accept a nut on the exposed end.

Bolts and studs can be repaired with a thread straightener found at Napa or other automotive outlets.

I assume you mean the threads in a hole are stripped.

Female threaded receiver can be repaired with a bottom tap and if not repairable with a bottom tap, with a Heli-coil. The Heli-coil must be the same thread as the bolt (screw) threads to use the same bolt. A Heli-coil kit comes with a drill and tap and several heli-coils.

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HomerJSmith

A Heli-coil would be the best solution, but if it isn't an option, you might try this. Take a bolt that's 1/2" longer than the bolt that they replaced and cut the head off and use it as a stud that you can put a nut on. Take the stud and put J-B weld epoxy on the stud that goes into the damaged hole and a little epoxy in the hole and screw the stud that you made into the hole until it bottoms and wait 24 hrs to set up, then put the nut on the end of the stud. Epoxy will get harder as time goes on.

EBEBRATT-Ed

Get a new bolt. Get the correct drill and tap and drill the hole carefully (don't go any deeper). Run the tap in with some cutting oil and clean it out. If the threads in the boiler are really stripped you can go with the heli coil.

HomerJSmith

Is the buderus aluminum? I would try the least risky procedure first, J-B Weld, if the door is under 500 deg. Heli-coil can be a tricky operation. You are not going to find a drill that doesn't have a coned tip which will drill deeper than the threaded hole. You don't want to dill thru a water jacket. Be careful is the operative word.

newagedawn

freaking gorrila's, what was it thinking

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KC_Jones

M12x1.5 is a bolt with a diameter of 12mm and the threads are 1.5mm spacing. It's similar to US standards just in metric.

The M12x25 would be 25mm long (best guess) and they probably didn't mention thread pitch assuming standard thread which should be 1.75 for that bolt diameter.

Shalom

Wondering if they got the bolt cross-threaded and stripped the hole that way, rather than overtightening. Maybe the door was hanging on the bolt, pulling it at an angle when they started it in, and they didn't realize until damage was done.

@HomerJSmith I remember when we used the Helicoil back in '91 or so, we resharpened the bit to have a wider angle at the tip, and ground the end of the tap flat, so as to leave the bottom of the hole as flat as possible.

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HomerJSmith

M12X25 is 12 mm bolt dia and 25 is the length, about 1". The thread pitch is not mentioned. A 12mm bolt is about a 1/2" bolt dia., as mentioned.

Auto parts stores do sell a rethreader kit for engine blocks that need new threads in a female connection. I think it is made by loctite. The way it works it you put in an epoxy(?) into the female threads and coat the bolt with a substance and screw the bolt into the female hole and let it set up and then the bolt can be unscrewed. It will with stand hi heat and it is strong. Try the least invasive thing first.

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HomerJSmith

M10 is dia., 65 is the length in mm, 8.8 is the grade, strength.

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the_donut

Depends on local code.

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Pumpguy

Frequently what I do in a case like this is to tap for and install a suitably sized pipe plug. Then grind off flush with the surface, and then drill and tap the plug for the bolt size you need.

Then be sure to put some Never Seize on the bolt threads so it comes out easy next time. If you don't use Never Seize, you may find the pipe plug unscrewing instead of the bolt.