Onan Id help needed...

[KE4AVB]

Dang it...Will need to pull the engine to even get the flywheel off. Surely wasn't meant to be serviced easily.

[bgsengine]

Dang it...Will need to pull the engine to even get the flywheel off. Surely wasn't meant to be serviced easily.

Unless you really HAVE to pull flywheel I wouldn't - if it's ignition I would test with a test light - set the test light probe (with lead clipped to B-) on o9ne of the coil terminals (I forget which) and crank the engine and watch for the test light to flicker on and off (one terminal or the other should do that while the other is 12v steady, so I think it would be the - side of the coil that should flash) - If it does that you know the coil triggering is working (just like with points) so it would most likely be a bad coil - Must be they reduced price (or the coil is aftermarket?) Some years back there were problems with the coil, so they had an update kit that lifted the coil up higher for more cooling the retrofit kit was like $235 USD (though, it was through Toro where we got them through) - Just a thought, might save you tearing the engine out if you dont have to..

[KE4AVB]

Tnx. I got a test light I haven't use several years in the tool box. I know which on the two is from the ignition so that should be the steady voltage it was dropping close to 6v during cranking so something now right. But I will test the other terminal in the morning. One question though this is like the Brigg oppose where both fire at the same time? Just thinking if so I might have a shorted plug.

Forgive me for being off on this one as I haven't dealt this type of coil system in very long time. The last vehicle I had coil problems with was my 67 Chrysler 300 and that car has been gone 25 yrs now so I am very rusty as I have forget most of that knowledge.

I did just think of something I better do and that is to get the rear wheels off the ground just in case it starts up. Don't want it to do like the kids ATV I started last year that took out across the yard before running out gas in the carb. The customer had screwed with after they turn down the estimate and then brought it down for to repair it. I had it where it would idle at start up and not full throttle.

[bgsengine]

Been a long time since I really had to think on it but I seem to recall these are something like the briggs twin opposed - but I think it is somewhat unique to Onan where they have to have both plug wires with a path to ground in order to fire as one side is the ground return or something like that ? That is, if you have one plug wire unhooked, I seem to recall somewhere that the other won't fire - in which case one of those plug wires being bad could cause it as easily as a bad plug (might be worth checking wire resistance on them and/or checking for spark right at the coil without the wires involved?)

[Arkie]

I have not read all of the previous but.

Appears you have one that Bubba has flogged and did not put all parts back into place.

I'm just going from memory here about a P series ign,

You should have a steady 12v or so to the pos terminal of the coil when cranking and a pulsing volatge to the neg terminal from the module. Both coil and module are expensive and the ohms values of the secondary side of the newer coils are not exactly what the service manual indicates.

The secondary of the coils are in series, therefore always have at least one spark plug wire connected or grounded when looking for spark on the other one. Also I've seen where some Bubba actually installed the wrong reach spark plugs and the engines would not run or start good. You can find a free Onan service manual to download with some searching.
IMHO: From what I have briefly seen and heard how the rig is eat up with neglect and no TLC I would back off that rig as a repair job for someone else. I only work on those rigs for myself, too much time involved in repairs and good reasonavbly priced parts hard to find. Parts are expensive, even used parts on flea bay are expensive. It would be a good rig for the owner to part out. Those were good rigs when new but!!!!!!!! After you get the engine running slight chance of Hydralics issues,such as leaks bad cylinders, etc.

Here is a couple links where some real good Onan guys hang out for info about checking the engine. I was borrowing their brains awhile back about some onan tips. Be sure and ask them about the new Onan replacement Ign coils resistance reading. The case site seems to be more user friendly.

http://casecoltingersoll.com/forumdispl ... an-Engines

This mytractor link is not user friendly using Internet explorer, operates better using google chrome and I think they have a library.
You will have to scroll around until you find the JD area in the forums. I'm not real familiar with the site.
http://www.mytractorforum.com/forum.php

On the old B43 and 48's with points ignition I've temporarily rigged two 12v automotive ignition coils primary's in series (too limit the current to the points) and got a test run. Just too see if I needed other parts other than a high dollar Onan coil.

Also their is a guy by the name of Skywatcher that hangs out on this site and he worked for JD and worked on the JD lawn tractors and is very familiar with the 200 and 300 series rigs. Might send him a PM if you get deep into it. He is good with info that is not in the Service book.

[KE4AVB]

Well fellows I found the problem this morning. There is very limited chance the guy told me the truth about having it running. I found two wiring problems in the coil area. First he had the oil pressure sensor wire grounded to crankcase. The other which was the actual cause of it not the firing was that the capacitor was connected to the wrong terminal. It needed to be on the 12V in side.

I will need to add a strap or cable ground from the engine crankcase to where the battery is grounded on the frame. Seen sparks this morning as I tried to start also when I pull the dipstick you see a couple spots on it where it has been arcing too.

Boy I hate it when someone that has no business even changing a light bulb attempting electrical repairs even though it makes me money by charging that stupid tax.

Engine has a fairly good oil leak that looks like it is at the oil filter adapter.

Operator says he only going to use the tractor for towing purposes and just want to be reliable for his mother to use doing so.

[Arkie]

ABout the oil leak at the oil filter adapter.

Quite common for the oil filter itself to leak on those if not 3/4 to 1 turn past snug, the filter itself has a tendency to vibrate loose and leak. They don't get the short filter tight enough usually.

There are collectors of those 318's, (who repair and re-store them themselves)but seems to me if a owner of those type rigs cannot repair them themselves they should not own one or have a large bank account for when they need repaired by a mechanic. Bubba's usually cause most problems on those machines and a mechanic has to fight his way through Bubba's
afterbirth in addition to making correct repairs.

JD needs to enter this tip into their service manual.

[KE4AVB]

It called reading the filter install instructions.

I found the oil leak after I got the engine running. It also explain why the light only went at full throttle. Dumbo replaced the oil pressure regulator bolt with the wrong thread TPI. He also removed the spring and plunger so there is no flow regulation; just full bypass.

Plus I have a failed Voltage regulator. NLA. Will need to convert to a 25A Kohler regulator and replace the melted connectors.

[bgsengine]

Plus I have a failed Voltage regulator. NLA. Will need to convert to a 25A Kohler regulator and replace the melted connectors.

Onan 191-2106 can be replaced by Oregon part number 33-411

[KE4AVB]

Kohler 2540332S should work fine just it has full wave rectifier with over voltage shut down. Just mounts a little different. The connectors that are melted are down line from the regulator. I would need to get them from Mouser.