Bob G radiator seeping from drain screw

RicB

RicB

True Classic
Installed one of Bob G's radiators many years ago and after opening up the drain screw I can't get it to stop seeping no matter how hard I try to tighten it. Anyone know what material and size of washer this would need? Thanks.
 
Are you using the bleeds screw that came with the radiator? If so, you may want to think about replacing it, as it really was more of a bolt than a bleeds screw. I bought one of these.
 
I'm not familiar with the "Bob G" radiator specifically, but it seems a standard copper crush washer should work. Either measure the drain bolt's size, or take it with you to the parts store to match the correct size washer.
 
Did the original come with a plug/washer? It is possible it's a pipe thread (NPT) plug, which would not use any washer, the tapered plug creates the seal. If that were the case, though, I would expect to see teflon tape or pipe dope on the threads. Was there any evidence of that?
 
There has been a discussion on Xweb about this before. They are 1/4 NPT threads. I believe the original plastic plug has an O ring that might have fallen off during the draining process, but it's been a long time since I looked at one. Others have swapped to a more common bronze drain plug that doesn't require removal in the future. Here is a link to some types, but they are available cheaper on EBay as well as most auto part stores. https://www.summitracing.com/search/part-type/petcocks
 
Sounds like you probably know what's needed. Just in case... The original radiator had a plastic plug with o-ring that may now be missing or damaged. I replaced mine with a brass drain and lotsa teflon tape. Seals and holds well. It was several years ago and can't recall if I purchased at FLAPS or eBay but there were several options to choose from.
 
Having a pipe thread on a radiator seems very unusual to me. However that means there are many types of drain valves that can be used in a 1/4 NPT fitting:
Drain_Valve_DV2_Series_Featured_459668ee-8230-438e-8fd8-180b70d34ba0_1024x1024.jpg s-l300.jpg images.jpg 30_ser5.jpg
 
Most of my radiator "upgrade" applications have been either larger standard units from bigger models of the same/similar vehicle, or custom aftermarket units made outside of the US. Therefore they tend to have metric fittings, which are all straight thread (not tapered like 'pipe thread'). So guess I just had not come across the use of NPT much on them. Thanks for the info. That being said, then a sealing washer of any type would not be of use here.
 
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