Engine block drain valve - replace with plug?

[Darrell_Walker]

The original brass engine block drain valve on my TR4A is leaking again. I've tried over the years to "rebuild" it, with varying degrees of success, but I'm ready to give up and install a plug. I could plug the valve internally, but I don't want some PFO (Potential Future Owner) cursing me. I didn't have time to drain the system and remove the valve, so I'm wondering if anyone knows offhand what thread size is.

TIA

 

[martx-5]

Well, I just received a new one from Moss just yesterday ($23.50). It is NOT a pipe thread, as is has a fiber washer to seal against the block. It measured out as 1/2"-20 threads.

Edit:
I have a TR3, but Moss lists the valve from TR2-'71 TR6.

 

[Tinkerman]

I have an original brass petcock(with a very loose spring). the threads are very definatly 18 TPI and it is a very loose 9/16 in diameter. I went to try it on the block and I have to admit I have no clue as to where it goes
:-(. So it ends up in the "for what its worth department".

Tinkerman

 

[Darrell_Walker]

It measured out as 1/2"-20 threads.

Thanks! I don't seem to have a bolt that size on hand, so I'll have to pick one up. Any reason to look for something other than plain steel, like brass or stainless? I'm pretty sure I can get stainless, not so sure about brass in that size.

-Darrell

 

[Bugeye58]

I have an original brass petcock(with a very loose spring). the threads are very definatly 18 TPI and it is a very loose 9/16 in diameter. Tinkerman

That sounds like 1/4" BSP.
19 TPI, major diameter .518"
Jeff

 

[Tinkerman]

Yep, your probably right. I finally found the drain plug hole and the petcock I have, doesn't come close to fitting it! I had been looking in all the wrong places, heh. So I guess I bought an eBay wrong part! Thank goodness I didn't cough up to much for it. Might fit the radiator but thats all put up so I'm not going to worry about it right now.

Thanks, Tinkerman

 

[PeterK]

Moss does show a similar radiator drain petcock. That might have a different thread. (too cold to go check right now)

 

[TR4nut]

I'm not positive, but I think the radiator valve and engine block valve have the same thread. I broke the handle on my engine block valve out of stupidity and was considering replacing it with a spare radiator valve I had - I remember them looking the same thread-wise.

Randy

 

[rotoflex]

It is not a drain valve.

It is there so you can pull over at 4pm & have hot water to make tea.

Remove it? Do you want an English car or don't you?

 

[Darrell_Walker]

It is not a drain valve.

It is there so you can pull over at 4pm & have hot water to make tea.

Remove it? Do you want an English car or don't you?

Ahh, now I see the wisdom. Nice green tea, as well!

-Darrell

 

[Darrell_Walker]

Quick update, a 1/2" fine thread (20) bolt fit perfectly. Got a stainless steel one, and a copper washer.