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Need JD 420 Garden tractor help:

3988 Views 44 Replies 10 Participants Last post by  billy_cravens
Has Onan 218 (instead of Onan 220) and was running great for several years until tractor just stopped one day a few weeks ago after 30 minutes cutting grass. Would only restart after sitting for a while. When restarted the tractor was running somewhat roughly and the RPMs were very low. Changed oil and filter, replaced spark plugs and wires, new air and fuel filters. Still runs as before with RPMs not near where they should be and are very low. And as before, I can run the tractor for a while, shut it down, but it will not start back up until it has cooled again. What approach should I take to troubleshooting? Should I be looking for vacuum leaks, carb problems or governor/throttle adjustments? I have a 420 service manual as well as the Onan engine manual, but I am looking for advice on the best area to start investigating. I've already had to have someone else cut grass for me once
and I've got some dirt to move!

...and thanks Dave T. for pointing me in the right place to post this!!
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I've had mine out several times and have never removed anything other than the grille, hood, and side shields.
This is my first time and I was hoping to just make more room by removing the firewall, but I see your point, probably just making more work for myself, I'm good at that!!
Take the battery tray out to get access to the bolts that hold the drive shaft to the flywheel.
Undo the bolts that hold the engine to the frame of the tractor.
Slide it forward, lift up and undo the cable going to the starter.
Two people can lift the engine out safely.

An automotive machine shop can take the remainder of the valve seat out, prep for a new oversize seat, and press the new one in place.

I paid just over a hundred for that including a valve job.
Thanks for the tips!! I hope the loose valve seat is the only problem.
I loosen my bolts with a 1/2" long handled wrench and then reach in with a nut driver to finish taking them out.
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