Pulled the compressor head off before flipping the compressor over, otherwise the oil would end up on top of the pistons where it doesn't belong. Same reason they say transport a fridge upright. It has a compressor.
The hole was right underneath the flat bar that's part of the wheel assembly. That center hole is factory, probably for alignment when welding the wheel support flat bar to the tank. Air was coming out that plus right behind the flat bar where that tack weld is.
Cut the tack weld and jammed a screw driver under it and found the hole which was smaller than I imagined.
Cut and bent up the flat bar to give me room to grind and weld a patch over the hole.
Found a piece of wider flat bar that happened to have a curve on the end that matched to round tank.
Thought I took more pics and know I did of the other little hole I found further forward on the tank but I don't see them on the phone. That other hole, I just welded a 3/4" circle around and then filled circle with weld. I'm guessing there's a rusty stripe down the middle from end to end on the bottom of the tank and more holes will blow out at some point. It's from people not draining the water out as often as they should. It was far from new when I got it but I'm guilty of the same.
Put it back together and fired it up. No leaks out the bottom. Slight leak at the pressure switch which has been there for years. I also took the compressor head cap off and cleaned up the reed valves. It could use a new pair if I can find some but for now, it's a decent little compressor again.
When I started it with zero pressure, it climbed 1 psi per second until it got to around 60 psi and then took a little longer than 1 psi/sec. It reached it's shut off point of 125 psi in 2-1/2 minutes.
I left it on and in about 20 minutes that pressure switch leak made it lose enough pressure to kick on and then it ran for 20 seconds, made it to full pressure again and shut off. Once upon a time, I could turn this thing off at full pressure, turn it back on in a few days and it wouldn't run because it still had full pressure. It was a tight little thing. I'll have to look into getting a pressure switch or the one little part of it that leaks.
So I've got the nice old little chugger for up at the house and the new high rpm screamer for down at the shop. I think it was the movie Dumb and Dumber which had the line; "Want to hear the most aggravating sound in the world?" and then Jim Carey makes an aggravating sound. That's this new compressor. Kick myself in the butt for not having looked at the rpm or looked up a video, with sound, of one running. It's gonna have to have it's own little shed and maybe with the inside lined with that acoustic foam with the egg carton shaped surface for soundproofing.
I'll be keeping my eye out for another old chugger but bigger than what I have. Then I can pawn off the noisemaker to some deaf person.
And Diana, you'll be happy to hear that I completely cleaned up from this project and even went a little further to move something I was tripping over to the travel trailer, as excruciating as that all was, like a bad dream to me now;)
Then I went food and hardware shopping. Grabbed another 10x25 sheet of black poly and a cheapo gate latch for the newly opened back door of the shed and a 50' air hose. I forgot ends for it so I'll grab them tomorrow. Gonna go put the latch on lay one sheet of poly down but I'm about whooped once the sun's down far enough. Next T, W, T, I'll get more stuff done around here.