• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

Engine block drain valve - replace with plug?

Share this page

Darrell_Walker

Darrell_Walker

Jedi Knight
Offline
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
 
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.
 
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
 
martx-5 said:
It measured out as 1/2"-20 threads.
Click to expand...

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
 
Tinkerman said:
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
Click to expand...

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

Attachments

  • 9265.jpg
    9265.jpg
    47.7 KB · Views: 135
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
 
Moss does show a similar radiator drain petcock. That might have a different thread. (too cold to go check right now)
 
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
 
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?
 
rotoflex said:
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?
Click to expand...

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

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