Removing union nut / stem for replacement (from cast iron radiator)

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Old 01-30-13, 09:58 PM
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Removing union nut / stem for replacement (from cast iron radiator)

I recently cracked the union nut on one of my cast iron radiators.
I wondering what the best approach is here to fix it....

I've read that removing the 'stem' is not always a smooth process... any tips? other suggestions? (heat it with propane torch and hit it with PB blaster/WD-40 first???)

I have a new value that came with the 3/4" FIP (or is it MIP?) union nut and 'stem' ( i think it's called a stem...)

The new stem looks too short compared to the one that's on there.

So, my thought was to:
a.) clean, and spray with PB blaster / WD-40 first, then let it sit for a while (the old 'stem')

b.) heat it with a propane torch for a little (putting some wood scraps under the radiator legs just in case.. to prevent my flooring from getting jacked up)

c.) try to remove the stem - would i buy and use this-> (Radiator spud wrench)Radiator Spud Wrench-B8618 at The Home Depot

d.) take off the old union nut (that i cracked while trying to tighten up a leak)

e.) replace the old union nut with the new one that I got with the 3/4" valve

f.) reassemble with teflon tape, carefully (using old 'stem' not new one b/c it looks too short)

g.) drain system (it's capped off right now), attach new valve to new union nut (reattach radiator)


Any suggestions otherwise? Tips on removing stem... tools to use?
[ my other thought was to forgo the radiator spud wrench and just crank on the outside of the stem with a pipe wrench.. but i thought i might break more stuff if i went that route..]

Here are some pictures:
radiator Photos by toddoskin | Photobucket

Thanks!
 
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Old 01-31-13, 02:56 PM
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The rad nut

Yeah, first get the nut off. I see it's already cracked so it shouldn't be too much trouble. Now the spud. This is never easy. You can spray penatrating oil on it before you start. You have to set up some kind motion. I would first tap the bushing that the spud screws into. Use a small ball peen hammer, or a claw hammer is fine if you dont have the other. Tap all the flats on the bushing, go around a few times. Then tap the brass spud a few times around, then a few good smacks on the end. Spray the PB or whatever you have one more time, then you can start to get the spud out. Use the spud wrench, tap it into the spud
but not too hard, you don't want to expand the spud too much, then try to back the spud out. It night take a couple of rounds of the above to do this. Of course, the best thingwould be is to get that bushing out, if the spud gets destroyed. Or you can collapse the spud by using a fine or med hacksaw blade and make three or four cuts in the inside of the spud, then try to collapse the spud , as the saw cuts will weaken it, then try to back it out, or just continue to collapse it and remove it that way. When you make the saw cuts try not to go into the threads.
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Old 01-31-13, 03:25 PM
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Might try cleaning the paint from around the threads where the spud meets the bushing so the PB can work it's way in.

I believe you are looking to take the old spud out, put the new union nut on, and put the old spud back in?

And you bought a whole new valve just to get the union nut for replacement?

I'm not real clear on your plan...

Did you try the new union nut on the valve to make sure it fits?
 
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Old 01-31-13, 04:28 PM
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The rad spud

I re thought this job, Use a medium size [about 1/4'] punch, and with just put it on the spud rihgt up against the bushing, and try to collapse the soud into itself about 1/4 of an inch and that might loosen it enough to back it out. The length of the new spud should not matter, you can slide the rad to make it up.
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Old 02-04-13, 04:42 PM
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Thanks guys! It worked!!!!! I got it off!

​So I was able to get the old spud/tailpiece off, pipe doped the new one, and screwed it back on.


I didn't reconnect the radiator yet, so I don't know if I have enough play to make up the ~1/4" I'm short by (in comparison to the old spud length).... but we'll find out tomorrow or whenever i attempt to reconnect the rad.


Here is how I did it (very similar to how i guessed in the original post)


a.) drained as much water out as i could (lifted one side, while other side of radiator had a cup underneath it).. then laid rad on its side.


b.) cleaned, and spray with PB blaster. scrapped with flathead screwdriver (especially where stud threads into bushing)... tapped with hammer lightly (on the spud)..then let it sit for a while , then repeated process again


c.) heated it with a propane torch for ~1 min (on the bushing, not the spud)


d.) Stuck the radiator spud wrench in the spud. Threw a 18" pipe wrench on the spud wrench. slowly cranked it off... didn't take much effort....


e.) replaced the old union nut and spud with the new one that I got with the 3/4" valve


f.) reassembled with pipe dope, so that the spud was sticking out about as far out as the old one (old one was 3/8" longer, and it was sticking out ~1 1/8"... new one was 3/8" shorted, and i screwed it in until it was sticking about about 7/8" -> 1")
 
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Old 02-04-13, 04:48 PM
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Got all 9 of my fingers crossed! I think it will be fine...
 
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