I screwed up. How to plug bleeder hole in cast iron radiator?

eclecticmn

I tried using an EZ Out to remove the bleeder valve from a cast iron radiator.
It sheared off. There is some soft metal inside the hole.
I drilled out the hole.
I now just want to plug the hole. I will add a bleeder valve elsewhere in line.
Perhaps solder in a bleeder valve.
Perhaps use JB Weld?
Any ideas?

mattmia2

drill it to the next size and tap it for a 1/4" plug. once you do that you could adapt it to the new bleeder. a cobalt bit might help drill through the easy out.

EBEBRATT-Ed

Depending on what size your hole is, drill the correct size hole and get a pipe tap and some cutting oil and tap some threads. If you have a good hardware store around they may have this or you could order what you need from McMaster Carr on line. You may want a tap wrench but you can use an adjustable wrench in a pinch. The drill bits I listed are the right size for the taps.

Is this hot water or steam??


!/8" pipe letter "R" Drill, (just over 5/16")

1/4" pipe 7/16 drill,

3/8 pipe 37/64 drill (just over 9/16")

Then buy a pipe plug or the right size bushing to install you vent.

hot_rod

as mentioned above, then get a flush plug, which is a flush, recessed plug that uses an allen wrench.
Keep running the tap in and testing the plug until it is just flush, use Loctite thread locker and tighten to flush or just below.

I suppose you could use some Bondo if you want that plug to disappear.

eclecticmn

I have never used a tap before. The radiator is hot water. What is the standard size of the cast iron radiator manual bleeder valve? I imagine the small bushings could be found on Amazon. I never looked for one that small before.

I could try to tap then use Bondo if it did not work correctly. I never thought of Bondo, just JB Weld. I wonder which is better. I used Bondo before for filling in rotten wood and autos.

Tinman

If you can turn a wrench, you can tap a hole. It’s really that easy. I always use a little bit of tap oil even it’s a small hole. With a newly drilled and tapped hole, tape and dope should work fine. Any hardware store will sell the tap you need and you can find a drill size/tap size chart with a quick Google search. 

mattmia2

Just be sure to reverse the tap to cut the material removed in the previous cuttings every 1/4 to 1/2 turn or so and don't put too much force on it, you don't want to break the tap. If you start feeling a lot of resistance reverse and go forward a little further.

Hot water coin key bleeders are usually 1/8" npt. You can use a 1/8 x 1/4 npt bushing or a reducer and 1/4" nipple. I would use brass and use teflon dope so it is less likely to get stuck in there. May need to use dope and tape if the threads are messed up.

WMno57

How big is the hole? What size bit did you use to drill it out? If enough of the original threads in the radiator are left, you could clean up the existing threads with a tap. Don't screw the tap in more than necessary. The hole is tapered, and if you screw the tap in all the way your new bleeder wont seal. Install a new standard size bleeder with some teflon tape.
If you decide to go oversize and cut new threads, lube the tap, and back it off 1/4 turn every 3/4 of a turn to break the chips. Otherwise the tap can break off in the hole. Then you have a bigger problem.
The suggestion to use Bondo was to make it pretty, not to seal the threads.

eclecticmn

I assumed Bondo was to plug the hole if all else failed.

MaxMercy

eclecticmn said:

I assumed Bondo was to plug the hole if all else failed.

Heheh... no.

While a good two part epoxy properly mixed and applied into a perfectly clean hole with some sort of thread to grip to will hold for a while, it won't last forever. J.B. "Weld" is nothing of the sort. It's a two part epoxy and nothing more. A good welder could weld the hole shut yes.

bucksnort

Surprised nobody mentioned Flex Seal.

psb75

Watch a YouTube of someone tapping new threads in soft metal. Use a little light-weight oil while cutting in the threads. Back the tap out frequently to remove cuttings. Go forward carefully and keep the tap perpendicular, especially when starting.

mattmia2

Use cutting oil or grease. it has an extreme pressure component that ordinary motor oil does not and works much better for tapping(or drilling for that matter)

eclecticmn

Thanks to all. I ordered drill bits, taps, and T handles to make the 1/8 and 1/4 pipe threads.
I ordered from drillsandcutters.com. I did not even know there was an "R" size drill bit.
I did not need a complete set of good bits or taps.
I still need the best backup to plug the hole in case my attempt to make the threads fails.

Lance

Skills cannot be taught verbally. They must be demonstrated, practiced and repeated until the skill has been accomplished. Your best backup is a wooden dowel or tapered wood plug and a good hammer and most of all I'm sure you will have shutoff the water and drained the system before you start. There are many other methods to quickly plug an unexpected Problem hole, lead wool, glue, I was even told how a gas pipe leak was plugged with a potato. Also the finger works if you don't mind waiting for help and the pressure is not too much. I plugged a broken pipe on the bottom of a 275 Gal #2 fuel oil tank with my finger, until my client found what I needed in my truck one late night. You are right to be prepared. I now prepare very carefully when faced with potential risks of failure. What surprised me was finding a 60 Psi copper water pipe joined in a coupling that was never soldered and was leak free for 10 years. Go figure!

eclecticmn

I am waiting for the drill, tap and handle for 1/8 and 1/4 NPT.
Just in case, I found a review of various epoxys from Project Farm. '
https://youtu.be/R3r0UZ7txzs
Which Epoxy Putty Brand is Best? JB Weld, Gorilla, Oatey, POR 15, QuickSteel, PC-7
BRANDS TESTED: Oatey, JB Weld, Hercules, POR 15, EP-400, Gorilla, QuickSteel, Loctite, KBS NuMetal, Pratley, A+B, and PC-7. Summary at 8:30, 10:16, 13:13

KBS nu metal best in tensile but expensive. JB Weld steel stick is good.
JB weld steel stick best in compression
PC7 best pipe hole repair sleeve JB weld second place
cylinder head repair
chain repair

bucksnort

Thing about using epoxy is if a piece would get into the system and meet the impeller of the circulator

hot_rod

If it is under pressure, really the best options are screwing a plug in, or welding a plug. Al those epoxy fixes are risky, there is not enough metal to bond to.

The local hardware or box stores may have a small squirt can of cutting oil, it really is the best way to cut threads.

If you have a good steady hand you can actually chuck the tap into the drill on low speed and run it in after you drill. The main thing with taps is they are hardened steel, very brittle, they break easily if you put too much side force on them, go slow.

eclecticmn

Thanks to all again. I got the R drill bit and tap for 1/8 NPT. Remnants of the old bleeder valve remained in the threads. I tried to clean out the threads but met some resistance and wanted to be careful. I ran in the R size drill bit without much resistance. Then I used the tap by hand, no handle, and cleaned out the threads. Then I screwed in the new bleeder valve with some blue monster dope. It never seemed to get real tight. It is not plumbed in yet and no easy way to pressure test in my house.

I now wonder how to make the fit tighter. I read about people using string in the threads but never learned where they got the string or what kind.

I also just realized that I might not be able to fit all3, 26 in high, 8 section cast iron radiators under those double windows (in that corner) and might have to settle for two so I might leave out the radiator with the new bleeder valve and put it under the single kitchen window when I find time. If I crammed in all three radiators I could not likely use unions (and other problems) and when the flooring was replaced there would be hell to pay.

MikeAmann

If you now have a thread that will hold a moderate tightening against the threads, use RED Loctite on the the threads after you get them completely clean. This will seal and hold up to the heat. The only way you can remove that bleeder in the future is to heat those threads with a torch to break down the Loctite.
Option 2 - plug that hole using a solid plug with red loctite and drill & tap a hole in a new location.
Option 3 - drill & tap that same hole to the next larger thread size and use a reducing bushing. In your case that would be 1/4" NPT to 1/8" NPT.

eclecticmn

When you say solid plug you mean a threaded plug? The new bleeder valve does thread in OK but does not get tighter as I screw it in further. I did not use the tap real hard either. I used my fingers without a handle to turn the tap and clean out the threads. Perhaps the EZ out did not damage. OR I am concerned about nothing.

I now plan to set that radiator aside and use the other two, then perhaps use red loctite when I get around to using the third radiator.

MikeAmann

Correct, a 1/8" NPT threaded plug. They have a variety of head choices and materials.

mattmia2

This is the string:
https://www.supplyhouse.com/Wal-rich-1906020-Ball-Wick

If it will tighten up string or teflon tape will help you. if it strips if you try to tighten it, you will have to drill and tap to the next size. You might try a nipple to see of that will get tight.

eclecticmn

MikeAmann said:

If you now have a thread that will hold a moderate tightening against the threads, use RED Loctite on the the threads after you get them completely clean. This will seal and hold up to the heat. The only way you can remove that bleeder in the future is to heat those threads with a torch to break down the Loctite.
Option 2 - plug that hole using a solid plug with red loctite and drill & tap a hole in a new location.
Option 3 - drill & tap that same hole to the next larger thread size and use a reducing bushing. In your case that would be 1/4" NPT to 1/8" NPT.

I finally got around to it again. I hired a mechanic to drill then tap threads in two of the radiators. I figured mechanics likely have more experience drill and tapping cast iron. However, I pressure tested the 1/4 to 1/8 bushing and it failed. Soap bubbles around the outside of the bushings. I tried blue monster tape also the paste. I forgot about the red loctite comment. I laid the radiator on its end so the threaded hole pointed down and the threads were horizontal. The I applied JB Weld high temp two epoxy around the bushing. One held pressure over night. The other is testing now with no soap bubbles.