Green Tractor Talk banner

1 - 8 of 8 Posts

·
Registered
Joined
·
33 Posts
Discussion Starter #1
I recently acquired a John Deere 425 with about 1300 hours and a sixty inch deck. It was in pretty rough condition and hasn't been used regularly for two years. The rear end leaks which I'm pretty certain is the diff linkage seal. I have pushed it back in and it reduced the leak to almost nothing. I'm going to replace at some point. My main concern is when I got it out seemed very underpowered. I couldn't now up step hills unless I was at a crawl. So through some research and troubleshooting figured out it was down a cylinder. I ended up pulling the valve covers and finding the intake valve push rod was bent and off the rocker and the exhaust valve push rod was straight but also off the rocker. I replaced both and now it runs quite well. Very strong even with the big sixty deck. I should also add that the exhaust valve was stuck so I sprayed with penetrating oil and worked it up and down until it moved smoothly. My concern is why did it bend the push rod in the first place and if I need to do more to ensure it isn't further damaged. It has run about one hour since replacing push rods with no issues.

I know nothing about this tractors history so not sure if cam gear has been replaced. I sorry assume it has but only because the hours are pretty high if it hasn't and clearly it hasn't been well taken care of.

Any thoughts on it I should just keep driving it and not worry unless it happens again or if I should rebuild engine. Or something else entirely.

Thanks

Jim
 

·
Registered
Joined
·
1,305 Posts
I would think any other issues would have manifested itself after one hour of run time. You can always change the oil and see what it looks like or even get it tested to see if something is coming apart.

If the engine was made after 1998 the cam gear issue was fixed. The manufacture date is usually on a sticker some where on the front of the engine if I recall. Interesting situation and it would give me pause as well, since you don't know what caused the valve to get bent. It had to have jumped time some how. I would at least look at the cam gear to make sure it doesn't have excessive wear.
 

·
Registered
Joined
·
1,690 Posts

·
Registered
Joined
·
115 Posts
If a lifter stuck from sitting, the piston would hit the valve and bend the pushrod, if you've had it running and all the valves are operating you are probably fine now.
 

·
Registered
Joined
·
365 Posts
If you have adjusted all 4 valves to their proper setting, let 'er rip. Change the oil again after a few hours. The valve setting should be checked on a schedule according to the manual. Probably around every 500 hours, just a guess.
If a valve sticks open for just for a moment the pushrod easily falls away from the rocker socket. A push rod could get bent because the valve was stuck in the closed position putting more strain on the push rod which bends it. Then it falls away. This might explain why one push rod was bent and the other was not. Kawasaki specs are very tight for straightness on those tiny little push rods. A slightly bent rod will bend more easily.
I wouldn't be too concerned about the cam, but if you should have to remove the coolant pump, you can see the cam gear through the opening.

tommyhawk
 

·
Premium Member
Joined
·
2,022 Posts
If the tractor was sitting, and the valve was stuck in the valve guide, and you just turned over the engine, that would have bend the push rod. So, the push rod getting bent could have just happened when you initially started the engine.

What caused the exhaust valve to jump off the rocker is sort of a mystery!!!

Change the oil if you already haven't and run it. You may get many hours out of it, who knows. One of the worst things you can do to any piece of equipment is let it set without ever starting it or turning the gears.
 

·
Registered
Joined
·
33 Posts
Discussion Starter #7
This is good news. The oil was terrible. I didn't have it analyzed and probably won't. I'll probably change oil and filter then in maybe ten or so hours see what oil looks like and maybe have it analyzed then. The engine was made before 98 so pretty sure it had the plastic cam gear from factory. I came from a John Deere 180 so really enjoying this 425. Can't think of a different model I would even want. Especially for the money
 
1 - 8 of 8 Posts
Top