My first JD was a 4020 LP I paid $5000 for it....1980 time line, and had to have it shipped 100+ miles to my farm. The weep holes on the side of the block were oozing fluid....had no idea what they were and what that meant......well $1000 and lots of work later, I found out that the engine had been into by somebody else, previously, and the "moron" that was into it the first time didn't know which color, cylinder sleeve O-ring went where....got the wrong one in the the right place and the leaking weep holes told you that something was wrong.....I forget the proper placement of the orange and black neoprene...probably orange for the water side and black for the oil side was how it was supposed to go but I got it per the manual.
That tractor started differently every time I attempted to start it.....it would run out of Propane half way through the afternoon of working, had to fool with the "Nurse Tank" drag along to the field thing, heat off the engine was intense. In the winter it was hard to fuel (low Propane pressure) and in the summer it had too much vapor, bled off who knows how much fuel to get the tank filled, again hard to fuel....get liquid to the tractor's tank rather than evaporating into the atmosphere while trying to get some liquid in the tank.
I got it sold (poor sucker) and replaced it with a JD 4010 diesel and I was in heaven........fueling was no problem, started instantly, winter or summer, pulled like an Oxen, miser on fuel, that I could refuel at the farm and didn't have to drag that nuisance nurse tank around, what a difference. Never bought a Propane again, and never bought any tractor that wasn't Diesel powered....after 45+years of "trying to learn how to farm".