Radiator Drain Tap

Has anyone found a source for the lower radiator pipe drain tap (1/4 bsp)? Everyone appears to out of stock with no BO date. The drain tap from Moss has a plug threaded into the threaded portion of the tap to prevent leaks, might as well just use a plug.
Per Moss
"To prevent any leakage and preserve the original appearance, we modified the design to incorporate an optional internal threaded plug. The plug is threaded into the drain tap with a sealing washer prior to installation in the radiator or engine block. When installed, the plug will reliably seal off the tap, preventing any leaks. And, as you have just realized, the plug will prevent any coolant from draining through the tap, no matter what you do with the handle. "

This is mine. I believe it is correct.

You might try Paul Beck Vintage Supplies.

They’re easy to rebuild. Just take apart, add a little valve grinding compound to the seat and work the lever back and forth for a good seal if you’re in the market for a used one. Be sure not to interchange this with the one on the cylinder block as they look the same. One has a 20tpi threads and the other 19 – I forgot which was which.


The tap on the side of the block is 1/2"-20 tpi. Same as the plugs for the oil galley. I belive they phased out then drain tap and replaced it with a plug on later cars.

Around 1968 the tap was discontinued and a simple bolt replaced it.

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Matches mine. It’s kind of odd the tap is closed when the lever is in line:

Both taps in my E, block and rad drain, when closed orient with the lever at 90 degrees, which seems more intuitive.

It bugs me to no end (the XJ radiator drain tap is the same way). It’s universal that the inline lever means it’s open.

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Don’t know why the “tap-engineer” decided to do it the other way. In the beginning I had the same problem regarding “open” or “closed” but now you know of course. See pic below of the radiator drain tap of my 1954 XK 120 (in the “open” position). And the second picture is from an old picture (of an FHC or DHC XK 120) showing the “closed” position.

Bob K.

I agree that the orientation of the handle seems backwards, but I guess one advantage would be you could tie off the handle against the tap head to prevent it being accidentally knocked open