My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information
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post #1 of 42 Old 04-02-2018, 04:31 PM Thread Starter
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My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

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.
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post #2 of 42 Old 04-02-2018, 04:39 PM
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

Throttle setting shouldn't have a noticeable effect on the compression test. You might try a leakdown test to see where the compression is being lost?
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post #3 of 42 Old 04-02-2018, 04:41 PM Thread Starter
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

Here are a couple pics of the machine/engine in process just to keep my hopes up.
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post #4 of 42 Old 04-02-2018, 04:57 PM Thread Starter
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

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Originally Posted by dave_r View Post
Throttle setting shouldn't have a noticeable effect on the compression test. You might try a leakdown test to see where the compression is being lost?
I'm working on that right now, I'm picking up a leak down tool in about an hour. Thanks!
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post #5 of 42 Old 04-02-2018, 07:00 PM
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

I've rebuilt 2 of these engines and never had to adjust the valves after initial reassembly. Did you replace the cam, tappets, and valve springs?

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post #6 of 42 Old 04-02-2018, 07:35 PM Thread Starter
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I've rebuilt 2 of these engines and never had to adjust the valves after initial reassembly. Did you replace the cam, tappets, and valve springs?
. I replaced the plastic cam with a new OEM Kawasaki metal cam gear. I did not replace the valve springs or tappets, the valve springs were well within spec and the tappets looked and felt like brand new. I just did a leak down test on the lower cylinder (oil filter side) and it?s holding great pressure. I?m having issues with the plug threads on the higher cylinder, trying to figure out if they?re trashed or not.
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post #7 of 42 Old 04-02-2018, 10:29 PM Thread Starter
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

After a lot of foul language and some tears Iíve accepted the fact that the plug threads are trashed on the upper cylinder. Iíll be back in a few days, Iíve ordered a replacement head. 😩
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post #8 of 42 Old 04-02-2018, 10:47 PM
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

there are thread-fixing kits for spark plug threads... gives you something to do while you are waiting...
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post #9 of 42 Old 04-02-2018, 10:47 PM
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

Really, a helicoil rethread would have worked. And then I doubt that had anything to do with your oiil leak issue. Did you make sure the crankcase vent system was in good condition?
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post #10 of 42 Old 04-02-2018, 11:18 PM Thread Starter
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

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Originally Posted by dave_r View Post
there are thread-fixing kits for spark plug threads... gives you something to do while you are waiting...
I looked at them but I found a head for $25, it was hard to justify wasting more money on the helicoil when I could do it right cheaply.
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post #11 of 42 Old 04-02-2018, 11:22 PM Thread Starter
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

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Really, a helicoil rethread would have worked. And then I doubt that had anything to do with your oiil leak issue. Did you make sure the crankcase vent system was in good condition?
I donít think the plug was causing my issues, the threads were a little messed up when I got it.

So I replaced the crankcase vent hose that runs from the block behind the carb up to the plastic nipple coming off the intake above the carb. I also replaced the square cover gasket on top of the motor, the little vent flaps inside looked fine. What else should I check for crankcase venting?
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post #12 of 42 Old 04-03-2018, 03:06 PM
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Did you ever determine where the oil was coming from? That would probably be the first thing I'd do. Especially considering it came to you with a "large ongoing oil leak." You might not have fixed whatever was causing it in the first place.
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post #13 of 42 Old 04-03-2018, 03:50 PM Thread Starter
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

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Did you ever determine where the oil was coming from? That would probably be the first thing I'd do. Especially considering it came to you with a "large ongoing oil leak." You might not have fixed whatever was causing it in the first place.
I'm in the process of stripping everything off the top of the engine (air box, radiator, etc) so I can get down to the flywheel. I'm assuming the oil is coming from the top crank seal but I won't know until I get the flywheel off.
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post #14 of 42 Old 04-03-2018, 06:40 PM
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

A few thoughts-- Are you sure you adjusted the valves at the proper position? I am also finding it unusual that the lash would change to such a degree in that short of a time frame. Did they become loose or tight? Sudden compression loss after valve adjustment just screams of improper procedure, resulting in the valves being held open and causing lack of compression.

On the cylinder walls, you stated it was bored .050" (hopefully you really needed to take it out that far to correct the walls). Did the machine shop also finish hone the cylinders or did they leave it rough-bored for you to hone? An overly-rough cylinder wall finish can destroy a set of rings within minutes. What indication do you have of high crankcase pressure besides the leak?

Just some things to start with, and go from here.
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post #15 of 42 Old 04-03-2018, 08:49 PM Thread Starter
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Re: My Deere F725 Kawasaki FD590V saga, my talent tank is offically on E

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Originally Posted by mattmag View Post
A few thoughts-- Are you sure you adjusted the valves at the proper position? I am also finding it unusual that the lash would change to such a degree in that short of a time frame. Did they become loose or tight? Sudden compression loss after valve adjustment just screams of improper procedure, resulting in the valves being held open and causing lack of compression.

On the cylinder walls, you stated it was bored .050" (hopefully you really needed to take it out that far to correct the walls). Did the machine shop also finish hone the cylinders or did they leave it rough-bored for you to hone? An overly-rough cylinder wall finish can destroy a set of rings within minutes. What indication do you have of high crankcase pressure besides the leak?

Just some things to start with, and go from here.
Great points Matt, Iím fairly certain Iím adjusting the valves at TDC checked both by confirming that Iím at the end of the compression stroke and using a pencil in the plug hole to show the piston is at itís upmost limit and closets to the head. The valves are fully closed with .10 gap. Enforce the rebuild I showed about 150psi in both cylinders. The machine shop bored it .50 because those were the easiest oversized Kawasaki pistons and rings I could find and it needed to be bored. .25 pistons were a lot harder to track down for some reason. The shop bored it and finish honed the block for me. Everything was smooth as butter, great looking crosshatch pattern on both sides.

I have no other sign of high crankcase pressure other than the oil leak but itís the only thing I can think of that would push oil out of the top of the engine when the seals are all brand new. The top crank cash bushing is new as well, there is no bushing on the bottom but then again the bottom isnít leaking either so Iím at a loss.
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