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Discussion Starter #1
Just bought a nice 420 from a guy that he told me up front has starter, flywheel problems. After pulling the engine it appears as though the starter did not engage all the way onto the flywheel, thus the ring gear is ruined and the teeth on the starter look bad also. When removing the two long bolts from the starter it looked like the starter wasn't lined up square to the enging. It was tight and all but seem to be leaning. Bolts were tight, but this starter was replaced once the guy told me. I am wondering if the wrong starter was installed? You guys ever had this problem. I just want to make sure when I replace the starter and flywheel that I get the correct one. Thanks in advance for any help.
 

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Sometimes one of the mounting holes on the block cracks, and that makes the starter not sit right. That would be the first thing I would check.
 

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What is the engine make and model number? There are differences between the Onan B and P series that had powered the 420 originally, especially the starters and oil pans. Is the solenoid mounted to the starter or separate?
 

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What is the engine make and model number? There are differences between the Onan B and P series that had powered the 420 originally, especially the starters and oil pans. Is the solenoid mounted to the starter or separate?[/QUOTE

The solenoid is mounted to the starter, but the problem is I'm not sure it's the right starter because it has been changed by previous owner....also having trouble determining what engine I have because the sticker on the shroud cover is unreadable. Also I'm not even sure of the serial number of this tractor because the sticker under the steering wheel is missing. My 318 has a metal plate with the serial number. I take it the 420's were stickers because this one is missing. Is there any other way to get this information. The problem with this whole deal is that this is the nicest 420 I have ever seen. Beautiful tractor! Thanks so much for your help, may need to pick your brain some more. I will send you some picks later. Tim
 

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I'm going to post some pics of my starter and flywheel and maybe that will help with what engine I have. I did check the starter mounting tabs on the block and they are not cracked. IMG_1478.jpg IMG_1477.jpg IMG_1478.jpg IMG_1480.jpg IMG_1482.jpg IMG_1488.jpg IMG_1487.jpg IMG_1483.jpg IMG_1485.jpg IMG_1484.jpg IMG_1486.jpg
 

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Was there a plastic ring on the crankshaft? Is there a module with wires under the stator 9th pic(the thing with all the coil of wires)
 

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In the 7th picture, the part number 140-4039 indicates it is a P series engine. Both Onan parts (134-4633) and JD (HE134-4633) are the new part numbers for the replacement ring gear/flywheel. The ring gear ( the part with the teeth) can be replaces without replacing the flywheel. The ring gear part number is 104-0779.
 

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That's good that the starter mounting tabs on the block are not cracked. That starter "should" be correct, but I can see that it is a "cheap chinese copy", and so the starter may or may not be the problem. If it wasn't made exactly right, starter/flywheel engagement would suffer.

The engine looks very clean and dry, compared to most of the ones I have dealt with.
 

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Thanks so much for the help. I think I will replace the ring gear and someone else said my starter looked like a cheap aftermarket replacement. This is a really nice tractor worth saving.
 

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starter gear does not look right to me but could be the angle of the pic
 

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As long as the engine is out, put new firewall insulation on, it helps the engine stay cooler.
Also, the oil filter to shroud gasket is missing (big air leak, needed for cooling).
 

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Sorry for the late reply. I don't see any module with wires under the stator. I'm posting a picture of what the end of the crankshaft looks like. I see your from Mid-Michigan. I was raised in the Owosso area and went to school there. I live in Northern Michigan now. Thanks for your input on my 420. I'ts a very nice tractor and I hope to get it running again. IMG_1496.jpg IMG_1496.jpg
 

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The ignition module is the trapezoid shaped black object just below the black plastic ring around the crankshaft.
 

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Great pick! I see the halo ring trigger and the tip of the module in the shot. One of your pics previously show 2 sets of bundle wires ( 1 for stator 1 for the ignition). Also it is the old style halo ring which had problems, new ones are white. That engine is nice and clean, who ever worked on it was meticulous (NASA clean room clean!! :lol:)
 

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So I have determined that I need a new flywheel ring gear and a starter for my JD 420. Who can I trust online to get quality Onan replacement parts? Thanks
 

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You must have worked pretty hard to get that engine that clean. Looks better than it did when it was new.

I have seen seen a few engines leak oil around the oil filter mounting bracket. Since you are doing all this work to it, I believe I would go ahead and put a new gasket on that. Boomer can get it for you or advise you on replacement if you ask him. I know it’s not leaking now but these engines ar getting old and it will leak sooner or later.

Max.
 

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Discussion Starter #19
420 flywheel, starter

You must have worked pretty hard to get that engine that clean. Looks better than it did when it was new.

I have seen seen a few engines leak oil around the oil filter mounting bracket. Since you are doing all this work to it, I believe I would go ahead and put a new gasket on that. Boomer can get it for you or advise you on replacement if you ask him. I know it’s not leaking now but these engines ar getting old and it will leak sooner or later.

Max.
OK, thanks I will be talking to him today.
 
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