Removing radiator plug

David_54

What is the proper/best way to remove a radiator plug without damage? Need to change from bottom entry to top entry for two pipe Trane system. It's a pretty standard rad - 10 section, 5 tube, cast iron. Thanks!

David_54

To clarify, it's not small plug for a vent, but the large threaded plug for the inlet toward the top of the rad.

B_Sloane

drill it, then use a screw extractor, or a sawzall

Hap_Hazzard

If it's hex, use a 6-point socket. If it's square, use an 8 or 4-point socket. Use a ¾" breaker bar. Lie the radiator flat so the torque forces the radiator against the floor. Apply pressure steadily, bracing one hand on the radiator so you don't fall on it when the plug gives. You can use a 3–4' ½" pipe as a cheater. Don't use penetrating oil. It won't help, and it makes the radiator smell funny.

EBEBRATT-Ed

If you find a socket that fit's it you might try an impact wrench if you have one. Be prepared to drill a hole in it and cut it out if you have too

Larry Weingarten

Hi, A trick that's worked for me is to use a cheater as @Hap_Hazzard says, and then while applying pressure, use a small sledge hammer to tap on the cheater. Turns you into a human impact wrench.

Yours, Larry

retiredguy

Try to tighten the plug first since the force and torque on the threads was in that direction. If it breaks it's grip and moves ever so slightly, then reverse the motion and remove the plug. If all else fails, be ready to cut it out. If you are not sure about cutting it out call someone who can help.If you cut into the radiator it will be ruined.

mroberts5

I've removed several with a torch and a 3-4ft cheater bar. The torch is critical as it will break the rusted joint loose.

Long Beach Ed

I've used all the methods mentioned here, but unlike Hap, I do use Kroil penetrating oil. I strip the paint off the exposed threads on the plug (if there are any) with a drill-mounted wire brush. I spray it with Kroil each day for a couple of days, beating on the plug with a 5 lb sledge from time to time.

After three or four days I take to it with a wrench and breaker bar. In stubborn cases, or when I didn't have a few days with my new friend, I've heated it up with an acetylene torch too. And yes, the penetrating oil stinks when you heat the radiator, but so does the pipe dope and new paint.

And I've cut them out also, but we usually get them out if we're patient and have a few days to work on them.

Hap_Hazzard

I think people continue to believe that heat and penetrating oil are effective in cases like this simply because they eventually get the plug out, so they think everything they did up until then somehow helped.

mroberts5

Here is a video I saw a while back where they compared the torque required to remove rusted on bolts for different oils and heat. https://youtu.be/xUEob2oAKVs

Heat wins - but not by a ton.

Hap_Hazzard

Those threads in the video are machine threads, and they aren't sealed with pipe joint compound. Also, heating a radiator and heating a nut are two very different propositions. When you heat a nut, you can do it without transferring very much heat to the bolt or stud, and the nut expands at a rate that is a factor of its circumference, while the stud would on;y expand as a function of its diameter. Consequently, the nut expands significantly more than the stud. Now, try heating up a radiator before the plug gets hot. And I'm not even sure that the tapping would even expand significantly as the radiator gets hot. It's complicated.

mattmia2

The main thing that heat does to loosen a part is it dehydrates the rust. It changes the chemical composition of the rust from a hard crystal to a soft powder, if you heat it sufficiently. The expansion and contraction and movement helps it break free as well, but changing the chemistry of the rust to soften it is the main benefit.

Hap_Hazzard

Plugs and other fittings that are installed with pipe joint compound generally don't have much in the way of rust in the threads because water can't get in there.

mattmia2

Depending on what the dope is it could help soften that as well. If there is no rust then it shouldn't take more force than what it took to put it together to take it apart.

Hap_Hazzard

mattmia2 said:

Depending on what the dope is it could help soften that as well. If there is no rust then it shouldn't take more force than what it took to put it together to take it apart.

Except that the pipe joint compound has hardened. I mean, it takes more effort to remove a piece of rebar from a slab of concrete after the concrete sets, right? So why wouldn't it be harder to break a pipe joint after the pipe joint compound has set? And, no, I don't think heat has any effect on it.

mattmia2

Concrete will turn in to a powder if you heat it. Most oxides will.

Edit: Technically concrete turns in to a hydroxide when you add water to it and that hydroxide turns in to a carbonate over time as it combines with carbon dioxide in the air. Heating drives that hydroxide and carbonate out and turns it back in to the soft uncured Portland cement powder.

ratio

My way is the easiest. 24" pipe wenches, with 48" cheaters, with a nephew big enough to eat hay. Worked every time so far!

Hap_Hazzard

ratio said:

My way is the easiest. 24" pipe wenches, with 48" cheaters, with a nephew big enough to eat hay. Worked every time so far!

What's wrong with a 48" pipe wrench?

But, seriously, you're absolutely right. It just takes brute force and the biggest wrench you can get your hands on.

SteamingatMohawk

For the small stuff, easyouts can work, but my opinion is drilling the hole in the center of the item, then driving in a left handed tapered easyout only expands the item you want to remove, increasing the holding force.

If you ever try it, be extremely careful if the item is much harder than what it is threaded into. I had a bad experience with a getting a stud out of an aluminum casting. The aluminum split before the stud came loose. Further if you break the easyout, the mess just gets bigger. Fore warned is fore armed.

SteamingatMohawk

If the item is small enough, I have drilled out the center and carefully collapsed the remaining material.

Also, it works for removing a copper fitting from a steel or cast iron fitting. It just takes patience and time.