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Discussion Starter · #1 · (Edited)
I was given a 318 P218G motor that was not running due to an "electrical problem" of some sort.
I'd appreciate some advice on what to test, and in what sequence to test.
I have TM1590 and CTM2 and PC1924.
It's out of a 1990 318, and the meter shows 796 hours. I do not know if the meter is accurate or working.
The Onan label is partially worn, but I can make out "P21" and S/N "A903637".
I have the motor mounted on a cart/stand, as I do not have the tractor.
It's missing a few parts, so my first steps are to locate the missing pieces.
The coil, plug wires, and battery cables are missing but I'm able to dig these items out of my spare parts bin.
The correct coil is HE 166-0761. That has been replaced by HE 541-0522, per the parts catalog.
I have a spare OE Onan coil - 166-0820, that I believe is good. It seems this coil is used in generators and 318s/P218Gs?
I searched out other posts for coil testing specifics, and found some specs.
I tested this spare coil and got the following ohms readings -
P218 coil Primary resistance should be between 2.90-3.60. I get approx 3.00.
P218 coil Secondary resistance should be between 14,500-19,800. I get approx 18,000.
It looks like this coil tests out as "good".
My first question is can I use this spare coil, 166-0820, on this P218G, and move on to the next item?
Thanks!
 

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The spare coil you have is correct, just checked the part number of my spare. I have a 318 with the P128G and a 420 with a P220G. The next thing is to check the electronic ignition module to see if it is sort of good (the module could die from heat issues, starts and runs for a while then dies due to heat). Then it will be time to check the compression. If that is all good, bolt down on a solid heavy table and see if it starts. ( Make sure oil is clean/filter). Hopefully carb is clean.
 

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Discussion Starter · #3 · (Edited)
Thanks!
I need the 2 (or 3) legged bracket that holds this round (replacement style) coil, 166-0820, in place on the top of the motor. I have not found that separately in the parts catalog or on ebay. If anyone has that available, or has a part number, could you please send me a pm? I am also going to try a few local JD guys I know for the bracket.
I have spark plug wires and battery cables. I need to repair some wires near the coil / regulator next.
I've read some posts where it indicates I need to wire in the electronic ignition when attempting to start on the bench.
I'm not sure how to do that, but will get to that later.

Edit - have found the necessary coil bracket.
 

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Discussion Starter · #4 ·
I've gathered up all the missing parts, and have installed them. I believe I'm ready to begin testing, but would like some advice to confirm whether I've wired up everything properly for testing on the bench.
(I've matched the wiring up to another 318/P218G right along side of it, but that motor is still in the 318 and wired up normally.)

This is what I've done:
The motor is bolted down to a stand.
Installed a used, tested as good, P218G coil - 166-0820.
Connected ignition module to terminals on coil.
Installed a new, repro, condenser, to match OE spec - 312-0256. Condenser attaches to (+) terminal on coil.
Installed used spark plug wires as the originals were missing.
Set plugs at .025.
Installed a battery and battery cables. (-) to ground at engine lift bracket, (+) to primary terminal on starter.
Installed wire with on/off switch between the battery + and spade terminal on solenoid. The motor does now turn over.
The engine harness is missing - I have a used one on the way. The middle terminal of the VR is not connected to anything. I don't think that is important at this time.

In some other threads, I just noticed that I should have another switched wire going from the (+) battery to the (+) side of the coil. I do not have this yet.
It looks like this wire is necessary to run, and when is shut off, serves as a kill switch.
Do I need this wire to do basic testing? I think yes, so I'll have to run out and get another switch, and wire it up.

Would appreciate comments on my wiring progress so far. Thanks!
 

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Ken, I don't know where/how you mounted coil, ignition module, or condenser, so I'll ask, "Are these 3 pieces grounded to engine?"
Just as a comment, it you need to get another switch, I'd get a pushbutton. Use pushbutton for starter solenoid and on/off for ignition control. And yes, you need a switched wire going coil to shut engine down! Bob
 

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Discussion Starter · #6 ·
Thanks Bob!
Coil, condenser, and module are all grounded to engine, installed in all the usual places.
Yes, I'm now going to get a pushbutton switch for the solenoid.
 
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