Why could JD 425 use oil after replacing plastic with metal cam gear?

[Rob50056]

It was the reed valve behind flywheel that was stuck open.
I rebuilt the motor with new pistons because one cylinder was weak and piston was out of round but the oil blow back was from dirty reed valve not sealing shut.
Runs great now.

 

[Rob50056]

It was worth rebuilding.
I have to have two mowers so I bought a hustler 0-turn 60 deck to get me by while fixing JD 425.
I went completely through motor,valve job,miked,etc...
Cost about 500.00 for new pistons,rings,gaskets,etc...
Let me say the the 425 is 5 times the mower than a brand new Huslter.
Just no comparison.
JD has full suspension,Hustler are just a solid frame and floating deck.

 

[4get gto]

Is there a way of knowing if your particular motor has plastic or metal gears..? I hear they should be changed after so many hours..

 

[beenthere]

4get gto
Hint... Read the opening statement.. as to how this started..

I think the last 425 engines with plastic were about 20 years ago...but may not be right on that..

 

[4get gto]

4get gto
Hint... Read the opening statement.. as to how this started..

I think the last 425 engines with plastic were about 20 years ago...but may not be right on that..

That's why I wondered... I have a Kawasaki twin that's over 20 years old with about 900 hours. Just wondering if there's a way to tell . Think there was a year when they switched to all metal gears.

 

[Amvcane]

4get gto,
I believe that a JD 425 with a serial number above 60001 will have a metal cam gear.

 

[ededic]

The JD dealer replaced the plastic CAM with metal on my 2000 6x4 JD Gator when they replaced the water pump because it was torn apart already and it had just over 1000 hours on it.



Gator is a little louder now, has the wine of a muscle car with an oversized cam. That, I don’t mind at all. Cleaning up with Gator 6x4 - YouTube

Never did replace it on my 1996 JD 345 with over 2000 hours. I sold it a couple years ago and it was running great.



The gator does not use oil after the new cam.

 

[Zebrafive]

Is there a way of knowing if your particular motor has plastic or metal gears..? I hear they should be changed after so many hours..

Change was mid 1998 model year. My 1989 JD285 went 1100 hours and 27 years. My 2 cents is the plastic becomes brittle over time and breaks. Mine broke at start up. So my opinion is more time/hours the greater the risk of it letting go. Heat could be a factor too, but mine never overheated.