Found another problem. Makes sense though - 3000 hours on the machine, it wasn't super well taken care of from new. Used a heavy plate compactor for preparing the hole for septic tanks mostly. That vibration is what backed out most of the bolts on this machine, what made it need new pins and bushing so soon, etc.
Anyway, was using it the other day, have a grand time! And smelled coolant on exhaust. well, crap! so I shut it down and got out to look. Coolant all over the engine, the bay, dripping on the ground etc. I let it cool, refilled the tank, and get it back to my shop. So it's coming apart now.

and it's a good brand radiator, and as it turns out copper! Well, that's fantastic! I can fix this.

play with it in a water bath looking for air leaks, I found only the one after a fairly intense search.

You can see the crack - it's running vertically with the tube nearest the white marks. So, today, I'm going to let it warm up a bit (that's frost on the fins), clean the paint off, and do some soldering. well, cool, I'm good with this!
I'll get another pic up when it's all back together.