Guys, I sure would appreciate some help if anyone has the time and knowledge. I purchased a John Deere F725 from a buddy knowing that it had engine issues, a large ongoing oil leak and a list of other maint. issues that had been put off. The machine shows 800 hrs on the clock but I highly doubt that's correct based on the wear and tear on the machine. I purchased this machine as a winter project with the option of parting it out once I determined the major issues. The machine didn't run but it would turn over and occasionally backfire through the intake. The engine spun smoothly but the compression seemed low when spun by hand. I pulled the plugs and valve covers to find 2 pushrods had fallen out but weren't bent. I pulled the plugs to check compression and found a broken/smashed spark plug which looked like it had been dropped, broken and installed anyway. I also found the oil level was way too high and a pretty good amount of fuel in the oil. After seeing all of that I parked it, pulled the engine into my shop and started tearing it down. I found the cylinder walls in good shape and really torn up on the inside. At some point before I bought it the PO had torn it down and replaced the top crank seal but had installed the replacement upside-down in the block. After seeing all of that I decided to do a full rebuild on the FD590V, I've always wanted to learn the process and I'm already a decent DIY mechanic.
Fast forward to now and the following has been done to this thing:
I had the block bored .50 over and the crank was polished. Everything checked out within spec.
The heads were done, new valve seals were installed and they tested fine.
I purchased new .50 over pistons and rings.
I purchased a complete steel cam kit with all the seals, gaskets, water pump, governor, etc. I also picked up a new fuel pump, a carb rebuild kid, new gov. arm and seal. Lastly I picked up a new air filter, oil filter, oil pump spring and ball bearing, thermostat, a few hoses and all new fluids.
I reassembled the engine over the course of the winter after the parts started to show up, I double/triple checked my work and it went back together pretty easily using the factor service manual. I rebuilt the carb and got everything back together a couple weeks ago. I spent a couple days getting the mower itself cleaned up and reinstalled the engine. I got it back together on Thursday and after adding fluids then checking to confirm the new fuel pump was pumping I hooked up the fuel line to the carb, hooked up the plug wires and she started like a brand new machine. She runs great, feels strong and sounds like a new engine. Here's a video from the first start.
Fast forward 2 days and I've gotten the deck back on it and I try cuttings some grass. After 10 or 15 minutes of a load the Kawasaki starts to leak oil from the top end, I can't tell where it's coming from because I haven't torn it down yet. I also check compression and I'm getting 125 - 135psi on both sides, that's less than I got before I tore it down. I pull the valve covers to check the valves and find them in serious need of adjustment after some run time. I adjust them per the manual to .10 and check compression again (valve covers still off so I can watch valve movement... now I get only 50 - 60psi on both sides. I'm at a complete loss for what the problem could be so I have a couple questions and would love advice from anyone who wants to jump in.
*When I checked compression I'm not sure if I had the throttle wide open, could the throttle being closed cause that much of a compression loss?
*When it started to leak oil from the top end I checked and found the oil level just a hair above the full line, I drained enough off to get it back into the XXX area on the dip stick. Could that have caused the oil to leak out of the top crank shaft seal?
*What could be the causes of excessive crank case pressure which in turn could be causing my oil leak issue?
*Why would pulling the valve covers cause a loss of compression?
*What would you try next if you were me? I'm about to start tearing it down again just to determine exactly where the oil is coming from.