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Duramax7man7

Onan P-Series Ignition Module Replacement [Photos]

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WHX??

GREAT write up Andrew  and thanks for sharing! May be doing just this pending final  diagnosis. :handgestures-thumbupright:

Edited by WHX11
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Duramax7man7

My pleasure mate! That's exactly why I did it. 

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lynnmor

Thanks for the excellent job.  :text-goodpost:

 

If anyone wonders why the Onans have a hotter rear cylinder, and valve seat problems, just look at how the oil filter mount and other parts block air flow.  If they wouldn't have mounted ignition and other parts to the cover we could easily pop it off and clean it at every oil change.

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Duramax7man7

True. but as long as it gets blow out with a leaf blower or compressed air after every mowing day, especially in the dry summer mowing days (more dust and lighter grass clippings get sucked into the air path easier) I think that should extend the duration in between having to worry about cleaning it out. 

 The issue I think mainly lies in owners that don't do this routinely. That debris build up, starts breaking down and then turns into insulation on that rear cylinder and causes failure. 

Still great engines! ;)

 

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rmaynard

:text-bravo:A picture(s) is worth a thousand words (and there might be a thousand words there too.)

Might want to get a MOD to pin this one to the top of the Engine section.

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Duramax7man7

I agree. I'm sure that this is a common interest with any Onan powered tractor owner... 

Here is a brief talk about it and the tractor running. 

Going to change the oil later today... 
 

 

Edited by Mastiffman
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EricF

GREAT step-by-step! :text-thankyouyellow:

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6bg6ga

I would say good job.  If I were to offer several ideas they would be to incorporate the troubleshooting of the ignition module, and coil prior to the disassembly process. You could probably sell it as a book.  The "Spark Ring" is nothing than a magnet. The simple test for that is will it repel another magnet. They very seldom if ever will go bad but may be damaged by junk like debris and such. They are what one would call a misunderstood part because most people simply like to throw parts at something thinking they are doing preventative maintenance. If it still will repel another magnet and is not damaged the part is still good.

 

You might touch on the importance of the thermal insulator under the module/sensor. Its job is to provide thermal protection. It is not to provide electrical isolation however.

Edited by 6bg6ga
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graywolf1939

Great job with demo photos Andrew! As others have mentioned, a picture is worth a thousand words. I have a 1988 Model 518-H that suddenly would not start after turning it off and trying to restart within 1 minute. One backfire and never to start again. Long story short, I pulled the flywheel today and found the key that mounts on the crankshaft and extends into the ignition ring broken. The only piece remaining was the part that sits into the depression in the crankshaft. I was looking at your photos of your repair of ignition module, but I could not detect the key beyond the end of the shaft in your photo. As I do not have the missing part of the key, I "assume" (bad word) that this key actually does extend all the way into the larger key-way slot in the ignition ring?

The long key that sits in the flywheel and extends a bit beyond the inside of the flywheel was OK. The Ignition ring was free to move without it's locking key to the drive shaft, thus throwing the starting effort way off timing as it could free-wheel around the crank shaft.

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graywolf1939

This is the key that is listed for the WH model 518-H, P218 Onan engine. My question is, which way does this mount on the crankshaft? If you insert the long end into the flywheel, there is not enough reach on the other end to reach the slot in the trigger ring. If you insert the long end into the trigger ring slot, the stub end is not long enough for the flywheel slot !! Are there TWO keys that must be used ? If there is only one key, does that mean that the trigger ring does not need a key in it's larger spaced slot, but uses just a friction fit on the crankshaft ?

flywheel key for Onan P218 engine.jpg

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lynnmor

I am currently working on a P220, this afternoon I'll pull the key if it isn't stuck, and let you know what I found.

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gwest_ca

Always amazed at the detail in the illustrations

Garry

Onan flywheel key.jpg

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lynnmor

I looked at mine and found that the long tail goes back into the keyway of the ring.  There is plenty of key in the flywheel so I don't know what you mean about not being enough for the flywheel slot.  Get a new key and it can only go one way without sticking way out.  It might be possible that the ring is damaged in some way that it moved back, perhaps it should be removed and inspected.

 

just noticed that the illustration shown above shows the key opposite the way mine is installed.

Edited by lynnmor

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Duramax7man7

The key on my tractor was simply a long key with no tab at the end. The spark trigger ring should sit on the crank in a manner in which it will be locked to the correct timing by the flywheel key. There is only one key. 

If your ring sits too far back then pull it off and see if it is damaged on the inside bore in which maybe it's sitting back against the timing gear cover to much and not locking onto the key. If it looks like its centered properly over the spark trigger sensor module, then check to see if there is damage done to the key way on the inside of the ring. If not then maybe, just maybe the key was replaced from a previous owner because of shear and the replacement key was a bit too short and has moved. 

 I would think that it was one of those three things. 

Hope this helps.  

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corpline

Do you still have the mower? I was wondering if you could send me a picture of the wiring on the ignition coil. I've looked at the wiring diagrams and it doesn't describe the wiring for the ignition coil. The issue I have is the new ignition coil I've installed is not producing a spark on either of the spark plugs and before I installed the new ignition coil I had taken a picture of the wiring. Black wire attached to the negative (or ground) post and ORANGE & YELLOW wires are attached together on the positive post of the ignition coil. There's nothing for me to verify this is the right setup. The old ignition coil looked to be fried and it was not producing spark. With wires off the ignition coil I did measure between ORANGE (in the picture looks RED) and both BLACK & YELLOW 12 volts as ignition key is turned ON. Which leads me to question the YELLOW wire. Any help with picture or description of the wiring is greatly appreciated.

Ignition Coil.JPG

Edited by corpline

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lynnmor
1 hour ago, corpline said:

Do you still have the mower? I was wondering if you could send me a picture of the wiring on the ignition coil. I've looked at the wiring diagrams and it doesn't describe the wiring for the ignition coil. The issue I have is the new ignition coil I've installed is not producing a spark on either of the spark plugs and before I installed the new ignition coil I had taken a picture of the wiring. Black wire attached to the negative (or ground) post and Red & Yellow wires are attached together on the positive post of the ignition coil. There's nothing for me to verify this is the right setup. The old ignition coil looked to be fried and it was not producing spark. With wires off the ignition coil I did measure between RED and both BLACK & YELLOW 12 volts as ignition key is turned ON. Which leads me to question the YELLOW wire. Any help with picture or description of the wiring is greatly appreciated.

 

 

:text-welcomeconfetti:

 

Go to the Wheel Horse Manuals section and download the manuals that pertain to your particular tractor.  There is also a Demystification Guide to help with electrical issues.  Finally download the manual for your Onan P220G.  With these resources, you can do proper testing and wiring. 

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corpline

Lynn thank you for the information but running into brick wall finding the supporting information you've provided.

 

 

Edited by corpline

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lynnmor
7 hours ago, corpline said:

Lynn thank you for the information but running into brick wall finding the supporting information you've provided.

 

 

Here is a place to start: Demystification Guide

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1995 520H+96+97

The studs on the coil are different size, large and small.

The terminals of the wiring of the ignition module are different size, large and small hole.

 

Edited by 1995 520H+96+97

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corpline

Thank you QWEST_CA (Gary) that's an awesome library. Unfortunately I have not found what I am looking for but with additional information I might be getting close. Based on the diagrams in the wiring manuals I see that I need to correct the color mentioned above from RED to ORANGE wire based information from the download library. Mystery continues on why no spark. Still strange to me that 12 voltage across (now corrected color) ORANGE wire and YELLOW wire with ignition ON. That's why I was hoping someone would post a color picture of their 520H ignition coil with wires posted so I can ruled that strange observation out of my list.

Edited by corpline

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cleat

Here is mine.

1877837826_NewChinacoilinstalled.JPG.a7677a5a0080fb4c11cff085642bd0e3.JPG

 

Red from the ignition control, yellow(ignition power) and the black from the condenser go onto the + terminal

Black from the ignition control goes to the - terminal.

 

Cleat

 

 

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corpline

Thank you Cleat :D I am still troubleshooting "no spark".

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Duramax7man7

You can test the coil itself but on the Primary coil (small wire posts) as well as the secondary coil (main spark coil posts) for continuity and proper resistance.  I believe the secondary coil will be around 16k-19k ohms...

IIRC, You can also test the wires coming from the ignition module for signal as you are turning over the engine? 

 Either way, you can find all that you need to know from the demystification guide for testing the ignition components to find your issue. 

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