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Discussion Starter #1
So I picked up a 1989 420 on Saturday. It needs paint and a tuneup, but for the most part it is in decent shape. The engine surges at full throttle, but runs smoothly at lower rpms, so I would think that maybe it's starved for fuel at the top end or needs the carb cleaned. I plan to buy a 3pt and load lifter for it and use it to move stuff around the yard and what not until I can find some attachments for it. Definitely a lot bigger than my 210 and 185.



 

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I like the line up comparison! Congrats on the 420!
 

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Nice find! :fing32: :fing32: :fing32:

Always god to have more GREEN!!! ~~ grnspot
 

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Discussion Starter #5
A little more about this 420. It has ~1700 hours, has the classic (I have learned) Onan surge. The TruPowers on the rear still have a ton of tread. I paid $420 for it.
I have purchased new filters (air, oil, hydro, fuel), new plugs and new fluids. I am planning to give it a good bath and remove the engine tins to clean out the fins. I have read that the surge is commonly due to the intake needing to be resealed. It doesn't look like this is difficult to do. It occasionally clicks when you hit the starter, I've seen that there's a relay kit that fixes this. I hope so, since it looks like you have to pull the engine to replace the starter.

Anything else to keep an eye out for or look at? This is my first Onan powered tractor. Does Onan make their manuals available like Kohler?
 

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A little more about this 420. It has ~1700 hours, has the classic (I have learned) Onan surge. The TruPowers on the rear still have a ton of tread. I paid $420 for it.
I have purchased new filters (air, oil, hydro, fuel), new plugs and new fluids. I am planning to give it a good bath and remove the engine tins to clean out the fins. I have read that the surge is commonly due to the intake needing to be resealed. It doesn't look like this is difficult to do. It occasionally clicks when you hit the starter, I've seen that there's a relay kit that fixes this. I hope so, since it looks like you have to pull the engine to replace the starter.

Anything else to keep an eye out for or look at? This is my first Onan powered tractor. Does Onan make their manuals available like Kohler?
I would encourage you to check out the 318 checklist, most of the same will apply to the 420.

Especially the fuel line part! The seafoam treatment, cleaning the carb, replacing the fuel lines, and new gaskets will almost certainly get rid of the Onan Surge.

With the seafoam treatment and 1700 hours it might be a good idea to decarbon the engine if the compression is still good. the seafoam has a tendency to knock loose carbon deposits that then get stuck in the valves causing all kind of issues.

See this is what happens when people get a deal, we try to come up with as much stuff as possible to add to the cost :) ($420 for a 420, you should feel bad and sell it to me for $840 and double your money).:ROF
 

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