Radiator drain

[snamelc]

The radiator drain on my Series II won't open. The bar that is supposed to open it just spins and does nothing. There's a hex "nut" up against the radiator shell but I don't want to damage my radiator by twisting on that if it is welded or soldered into the shell. If it's not, then there has to be a female thread that is welded or soldered to the shell and I can replace the valve by simply backing the old one out. Help! Which is it?

 

[RootesRacer]

If the "bar" is just spinning, someone has broken the solder that binds the "bar" to the actual valve.

You may have to remove the valve now to save it.
It screws into the radiator and is a fine pipe thread. BSP fine IIRC.

The drain valve BTW opens backwards compared to what you would think.
The pipe threads however are normal direction for removal.

 

[bmohr]

Just replaced mine although series 4. Good luck finding a new one with threaded BSP (British Standard Pipe). Mine was missing from when the radiator shop cleaned and tested it. Didn't realize until I was putting it in the car (10 years later...) I tried to fit the one from a spare Alpine radiator I had laying around, but it was NPT (National Pipe Thread). If you're careful removing yours, you should be fine to reuse it. I would recommend using some teflon tape or teflon paste on the threads when you reinstall.

And not to contradict Jarrid who has a lot more experience than me, on my car the drain valve or petcock opens by turning to the left. It is a reverse thread though meaning when you turn it to the left it goes up into the radiator.

 

[65beam]

drain

you can call sunbeam specialties and buy a brass drain or call VB and buy a plastic drain.

 

[snamelc]

Thanks all. I just took the old one out and it unscrewed just as predicted. I'll order a new one from SS.

 

[bmohr]

Just FYI. I talked to SS and theirs is NPT. At least that's what they told me.

 

[snamelc]

Yikes! OK, I'll wait until it comes and if it is NPT, am I up a creek without a paddle or can I tap the radiator out to NPT?

 

[bmohr]

To me there are some possibilities and options.

1) The SS part may be NPT and it might just match your radiator in which case put some teflon tape on it and you're in good shape.

2) The SS is NPT and your radiator is BPT. I confess I tapped mine with an NPT tap and it seems to snug up fine and hold coolant, but I haven't run my engine yet -- fuel tank issues.

3) If the SS one doesn't fit, you could just use your old one. The bar can probably be brazed back on but it doesn't have to be. That is really just a convenience so you can drain your coolant with out having to pull the plug and potentially have hot coolant splash on you.

Please let us know what happens.

 

[chazza]

... can I tap the radiator out to NPT?

Most probably not; as BSP and NP have different thread pitches and thread angles, so running an NP tap into the BSP hole will make a nasty mess!

If the replacement really is NP, then the easiest way is to send it back and order the right part from someone else. There is no excuse for the manufacturer having made it incorrectly, as BSP taps are readily available on the net.

Alternatively, the nut soldered to the tank could be unsoldered and a brass boss, already drilled, can be soldered in its place; which could then be tapped with NP.

Better than thread-tape, is to use Loctite Master Pipe Sealant, which will not allow small bits of plastic to get inside the cooling system,

Cheers Charlie

 

[bmohr]

snamelc,

Did you get your valve? Did it fit fine?

 

[snamelc]

The replacement valve came and the threads were the same. However, when I screwed it into the radiator, the valve would only open about half way and bottomed out on the radiator. Curses! Why did they make it so short? Anyhow, I went back to the old one, cut the worthless handle off, and soldered a brass hex nut onto the copper tube and it works great and opens all the way.

Bill