? Repair old cast iron radiator ?


Hi, I have an old cast iron radiator that is leaking between the sections. The joints are cone shaped, male and female, but the sealing takes place at the base of the cone which has a flat area about 1/4" wide. Two 5/8" threaded rods hold the 7 sections together. I've had them apart four times and they still seep. First I used permatex form a gasket by itself. Then I used the same stuff in combination with hand cut 1/32" thick gasket material. Then I used silicone gasket maker with the hand cut gasket material. My plumber says they can't be repaired and it needs to be replaced, but I'm not ready to give up yet - damn close, though. After all, it was put together once before and didn't leak for decades. I've heard that jb weld works, but if I use that and it still leaks, I might not be able to get it apart again. The fellow at the local plumbing supply store suggested using candle wick, yarn, or twine with the permatex or silicone instead of the 1/32" gasket material, theory being that the twine will conform to irregularities in the sealing surface better than a uniform thickness gasket. The fit is not precise, and assembly without any silicone reveals gaps almost 1/16" wide in some places. Oddly, that is not where it leaked, though. Unless I get a better suggestion here, I'll try the twine and silicone.
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wrote:

The trick is to wait until the silicone sets up before final tightening.
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Two questions:
1. Was there a gasket in there when you first took it apart? (I'm just curious, I've never had mine apart.)
2. Has the system pressure changed? Excess pressure could be causing the leak. In a hot water system, the system needs to be full of water, but does not need to be pressurized to work.
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Heathcliff wrote:

There were no gaskets, just a hardened orange sealant of some type. Same pressure - about 15psi. I need that much in order to bleed the radiator on the third floor.
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First time I replaced a thermostat on a car, I had a leak an hour or so later. Find out that the proper stuff is the #2b non hardening. The black stuff. Alcohol "dry gas" will get it off your hands, but it's easier to wear doctor gloves.
The #1 rapid hardening is useless.
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Did you get the sections back together in the right order? If in doubt. mark them and try the fit for different orders. One sequence may show promise and could lead to proper sealing.
Joe
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Joe wrote:

It didn't occur to me that the order might matter until I went to assemble it for the fifth time, and I noticed that I had trouble getting the 5/8" threaded rod through the holes and that two of the sections didn't want to go together. So, I dry assembled it trying different orders until I got the best fit and alignment. After trying permatex number one flexible with and without gaskets, silicone with gaskets, and permatex number two hard setting with twine instead of gaskets - all without getting it to seal, I decided to use JB Weld without gaskets. It's not leaking now and I don't think it will. If another one ever develops a leak, I will definitely *not* take it apart. I'll drain the system, clean up the area around the leak and try to seal it from the outside with JB weld. No, this is not an advertisement. ;-) Thanks for the replies. Henry
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You could leave out the offending section?
cheers Bob
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