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Catch can drains/petcocks. Need new ideas

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Gamble97

15+ Year Contributor
2,642
63
Jan 3, 2006
small town, Illinois
I used to use a typical petcock, drain but I'm really starting to dislike them. I made a catch can for someone, welded the 1/8" npt bung on the bottom from the inside so you didn't see any of the weld bead. Bought a drain fittings, threaded it in a few threads by hand and it wouldn't come out. Had to use pliers and it stripped the crap out of the threads. This has happened to me on many occasions. Anyone know what would cause this? Standard NPT threaded bungs from Summit, and brass petcocks from home depot or some online company.


So I'm looking for new drains, and still on the hunt for a decently priced site glass.
 
welded the 1/8" npt bung on the bottom from the inside so you didn't see any of the weld bead. Bought a drain fittings, threaded it in a few threads by hand and it wouldn't come out. Had to use pliers and it stripped the crap out of the threads. This has happened to me on many occasions. Anyone know what would cause this?
Tapered pipe thread relies on mechanical deformation to seal at the threads. They're really not meant to be removed and reinstalled over and over again. Are you using some form or lubricant on the threads? Using a lubricant such as pipe tape really helps relieve friction so that the threads will deform without galling. Naturally, it also helps it come apart easier.
 
It was the first time I put it on and took it off. I did use teflon tape but after putting it on and taking it off once the tape was peeled. Maybe I'll try a dap of oil.

Thanks Calan, I'll check out the link tomorrow at work.
 
The drain plug that came with my afco radiator was an interesting design. Not sure if you've ever seen what I'm talking about or not. I'll snap a picture later when I get to my shop.
 
What about using a bung/nut and using a bolt with a washer attached to the head and an o-ring?

I agree with Paul, using a petcock is nice, however I see the little hole clogging up as well.
 
Good call. A radiator petcock might work well on a catch can. It should be a bit more low profile than a ball valve and would surely be cheaper as well. The only issue I see if that it's small orifice might gunk up easily.

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That's exactly what I have been using. Maybe I'll try doing them again with lubing up the threads.
 
That's exactly what I have been using. Maybe I'll try doing them again with lubing up the threads.
For what it's worth, we use those petcocks on our Allstar aluminum catch cans and breather tanks, and once they're screwed on, they don't come back off. It feels like a heavy mechanical binding, which is a good thing for thread sealing but a bad thing for wanting to remove the fitting.
 
They also don't thread in very far either.
What are the ones that look just like these but have a tube at the bottom?
 
My personal favorite solution is to remote-mount the ball valve. I have an elbow threaded into the bottom of the can, and a hose runs from it down to a ball valve on a bracket, bolted to the frame. It makes access to the valve very easy while changing the oil, keeps it down low and out of the way, and doesn't get oil everywhere like a petcock drain does.
 
Could you just weld a nut to the inside and use a oil pan drain plug...they have been know to not leak
 
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