Can I just detach pump driveshaft from engine side only so I can start engine periodically without pump spinning?
I cannot think of a reason not to. But, why would you need to do that ?
A few years ago I had a buddy that had to move to a nursing facility and everything on his property had to be removed. He said if I got the JCB going I could have it. So, while trying to just start this thing after a decade plus hiatus in his back yard, I originally put the correct 32 weight in it but there were two pretty leaky cylinders and the rear king cylinders was even worse. It was just pissing all the fluid away so I decided to do a lighter 20 weight oil because it was cheaper. Ironically, I created more leaks as most of the seals didn't like the thinner oil but some were/are way worse than others. It will be a long process to repair the two cylinders I know are shot, regardless of viscosity as well as a few other issues. Thankfully, there's no rush since it's just kind of a hobby at this point. I'd just like to start it up a few times a month until I fix the worst cylinders and the other stuff. I do have a bunch of male BSP hose plugs for the individual cylinder's I was going to work on. However, I think I should have just ordered couplers to connect the input/output of each cylinder. I'm afraid if I just "plug" the cylinders input hose and the output hose it will create a back pressure to the pump.
Are the cylinder piston seals leaking internally or are they external leaks ? Plugging the hoses won't harm anything as long as you keep the levers that control the cylinders in the neutral position. Aw 32 oil is actually SAE 10W. The 20W you put in it is actually a heavier oil.
External. All the leaks probably drop a pint or more (combined) on the ground each time I start it. I guess I just assumed since more leaks popped up after switching to the 32 it was thinner. Does that most likely mean that the seals all failed because of their age or lack of use (dry rotted) or both? Just to be clear plugging (deadheading) individual hoses going in and out of each cylinder doesn't matter as long as no levers are used? Sorry, for my lack of knowledge. This is my first experience with complicated or large hydraulic systems. Power steering hose replacement or master cylinders here and there on cars is about as complicated as I've ever gotten. Do you recommend a different method to plug or reroute hoses or whatever that's safer or better than plugging a bunch of hoses?
More pics
More pics. It looks like the Kingpin was "repaired" b4 he parked it. I know he used the machine maybe 3 times after getting it back from these guys in St. Louis. That really sucks because the Kingpin leaks out more than the other stuff.