My Onan doesn't have spark.......

[Martin 2,132]

This thread deals with lack of spark or ignition issues with the P216, P218 and P220 engines used in the late 80s and all 90s tractors originally equipped with the Onan.

this would be your 3,4,500 series tractors that typically look like the one below with the Onan twin engine......

 

 

Parts of the manuals you will need to diagnose the issue........

 

 

 

testing of these components is also in the demystification guide as well.....

 

 

 

 

 

 

typical engine wiring diagram.....

 

 

 

Aside from any other issues, the coil and/or module are usually the culprits IF anything needs replacing. I say that IF, because not always are the ignition components faulty. it can be a simple wiring or terminal issue not letting 12 volts to the coil. if any components need replacing here is the part numbers you will need....

 

Coil 

 

Toro Part # 71-6000

Onan Part #166-0761(old part #)

superseded by part #541-0522 kit (includes a mounting bracket and 166-0820 coil to mount in the oem location) if you wanted to buy new.

If looking for used or nos use the 166-0761

 

or if you don't care about using the oem looking coil, a 3 ohm Harley coil can be substituted. 

 

 

 

Module.

 

Toro Part #71-6380, NN10444 (old number)

Onan Part #166-0785 (insulator if you need to replace it is 166-0786)

 

rarely do the rotor and condenser need replacing, but if you are after their part numbers here they are......

 

Rotor

 

Toro Part #71-6010

Onan Part #166-0767

 

Condenser

 

Toro Part #59-1180

Onan Part #312-0256

 

 

 

 

 

​Places these parts can be purchased (shop around the prices vary big time)

 

http://www.onanparts.com

 

Your Local Toro dealer

 

Ebay (harley coil)

 

check with Boomer a recent new member on the forum as well. I've heard his prices are good. http://www.wheelhorseforum.com/user/13637-boomers-influence/

 

 

 

 

 

I just threw this together fairly quickly, i would like a few of you guys out there to critique or comment on what i have here. maybe it need some additional input, maybe some stuff needs changing. i put this together in the hopes of helping some new to the world of Onan get one with ignition issues hopefully up and running. 

Edited September 3, 2014 by Martin

[Theroundhousernr 589]

I have a question about the insulater. Both motors I have taken apart so far have no insulater behind the trigger? What gives? Where they not installed on all models . I dont think anyone has worked on it before me judging from what I ran into taking it apart....I would like some insight on this before I start to put mine back together. Thanks Martin

   Kyle

[Martin 2,132]

both my 95s and the 97 parts engine had them, but i couldn't say whether all of them had them through the years. i only have 3 with modules.

[Theroundhousernr 589]

Well my 88 518h had no insulator. Just got done with a p216 out of a Deere " Excuse my langauge"  that had none. It was not over looked either. I was really paying attention for it on the second one and nope. No insulator. I am taking apart the 416H this week to replace the module to get it running again even though it smokes a little so its not a lead anchor. The 416 is a little newer with column controls. I will check the year tomorrow in the daylight.

 

  We shall see when I get into it. I would love some input from others that have had some torn down as well. Maybe I can call boomer tomorrow and ask him. I just find its existance odd in general. It can't electrically insulate it from the block because its bolted to it anyway. The bolts would carry the current regaurdless. So maybe its for........ I don't know. Good measure?

[Martin 2,132]

you got me! i don't have a clue why its there, shock insulation? like you said, the screws defeat the electrical part of it insulating. maybe they needed to add an extra $3.50 to the parts total for the engine?

[Theroundhousernr 589]

you got me! i don't have a clue why its there, shock insulation? like you said, the screws defeat the electrical part of it insulating. maybe they needed to add an extra $3.50 to the parts total for the engine?

lol Sounds about right. I wish I could have bought stocks in onan parts years ago.    Anyway, I hope this pertains to the post because If i ran into some engines with the insulator missing, I am sure others have/will too. And be scratching there heads like I am  . I did some google searching on the question at hand and came across some people saying" its important you install the insulator! ask me how I know"    Well yes , How do you know?? lol . No one every says why.

[Aussie 98]

Thanks for posting the information Martin. I purchased a non running 520H a few months ago which I haven't had a chance to look into yet. I will post up how it goes.

By the way I wish all of my 3/4/500's typically looked like yours.

[546cowboy 301]

Sometimes the insulator is stuck to the back of the module when you pull the module off and you may not see it. I believe the insulator is on there to dissipate heat build-up in the module and not to stop current. I couldn't say why one would not be on those and the module may not last long without one.

I have replaced several modules and I always make sure it has a good insulator before I reassemble the timing cover. Cheap insurance!

Pinning this is a very good idea since there are many owners who have never dealt with these engines. Onan's have an undeserved reputation for being unreliable and mysterious. That is far from the truth and if you own one you definitely need the service manual in your hands. These engines brought Wheel Horse from the 1950's into the 1980's in terms of power and reliability.

Edited September 5, 2014 by 546cowboy

[Theroundhousernr 589]

Cowboy, valid point. I think heat will build up regardless. I doubt there is much insulating property to that little thing. But could be.

To answer the other part. I meticulously clean every part when I work on something. So it was surely not missed. My used modules look brand new before I reassemble. I am hoping I find one on my 416 when I tear into. I would like to see what material it's made out of.

[Theroundhousernr 589]

  Just for the info. I just swapt out the ignition module on my 416H. It had the insulator behind it. So thats 1 out of 3 that had the insulator. It appears to me that the older onan motors did not have them on. Must have been a reason for adding them i guess. Or someone before me thought they where smarter than onan and removed them.  I dont beleive that was the case though.

So if yours did not come with an insulator, order it anyway. Just to be safe.  

 

 Also a quick tip to go along with the post. If after testing everything "coil , condensor, wires , module" and you are still it doubt and want to be sure before removing the flywheel , like I was.

 

 1- Disconnect the module wires from the coil ( leave disconnected)

 2- Connect the new or spare module up to the coil ( I happened to have a spare laying around )

 3- Bolt the module to one of the air filter mounting holes ( Just to keep it stable. You could also clamp it somewhere in reach )

 4- Pull plugs and ground them to the block , leaving them hooked up to the coil

 5- This part takes some practice. Turn Key On or jump coil from the positive terminal of battery. Using a spare ignition rotor, Rotate the rotor infront of  the module in same direction the motor turns over. It takes a full revolution to get a spark. You can not just pass a magnet in front of the module. Seems to act as a hall effect sensor.

 6- I could then hear/see the spark as I made a full revolution.

 7- If no spark. Repeat the steps in Martins post and double check yourself because it is not the module. In my case, it was and I felt allot better about pulling the flywheel.

 

 

 Of coarse all this means you must have spare parts laying around but it was a little test for me that justified replacing that part.

  

 

  Kyle

Edited September 6, 2014 by Theroundhousernr

[WH nut 553]

My turn. Is it possible to loose half the ignition coil, I fired up the 520 today and its only running on 1 cylinder. I can move the wires side to side and get the other cylinder to fire dut the one tower is dead.

[546cowboy 301]

Just so you know. This issue with the insulator is kind of like the issue with a GM ignition module in the distributor. The difference is GM does not use a material insulator. When you buy a module it comes with a little package of grease to be used on the bottom side of the module. If you do not use this grease the module 'WILL' fail and I have seen that happen. People buy one and think " what's this for and discard it" the next ting you know the vehicle won't start again. Time for another $60 for a new module plus the trip to the shop, towing charge and the labor. So you see not using that little packet of grease could cost you upwards of $200 to get it fixed.

Just saying "pay attention now or pay someone else later".

Edited July 20, 2015 by 546cowboy

[Save Old Iron 1,566]

the insulator is most certainly a thermal barrier and not an electrical insulator. The mounting bolts for the ignition module provide the ground connection for the module. The insulator is most likely sandwiched to the module to limit the thermal transfer from the engine block / oil pan into the module body. The flywheel provides some level of heat relief to the module and the insulator delays any "hot soak" when the engine is shut down. Further proof the insulator is used to prevent heat transfer INTO the module is the lack of any silicon grease on the module / insulator. Silicon  grease would indicate the designer was interested in extracting heat FROM THE MODULE as in the example given for the GM ignition module.

[cleat 5,955]

My 1989 520-HC has the insulator.

I installed new star washers to help ensure a good ground.

Cleat

[caddy 1 0]

I have a 520h model with the onan engine, no spark, Took it to my small engine guy, first he said it was the coil, got a new one , still no spark, got a new trigger module , still no spark, then he put some old plugs in the cable ends and he got spark, the whole problem was bad plugs, one was fouled completely the other almost completely  fouled up  so for 10.00 for 2 plugs  was affix, I had spent close to 400.00 for a coil and new module, which I cant return , but will keep for spares,  lesson well learned here , thanks Richard

Edited November 26, 2015 by caddy 1

[cleat 5,955]

Wow, I would think your small engine guy should be on the hook for at least some of the cost.

 

These ignition systems are not that difficult to determine the cause without just throwing parts at it.

 

Cleat

[Martin 2,132]

3 hours ago, caddy 1 said:

I have a 520h model with the onan engine, no spark, Took it to my small engine guy, first he said it was the coil, got a new one , still no spark, got a new trigger module , still no spark, then he put some old plugs in the cable ends and he got spark, the whole problem was bad plugs, one was fouled completely the other almost completely  fouled up  so for 10.00 for 2 plugs  was affix, I had spent close to 400.00 for a coil and new module, which I cant return , but will keep for spares,  lesson well learned here , thanks Richard

 

Sounds like you would have been better off asking here for help and taking a chance fixing it yourself. There are guides and manuals here and many posts and threads on your model tractors electrical issues. Over the years, I've found the best way to fix something I'm not familiar with is to learn how to do it myself. Not everyone is mechanically minded and i understand that some are just not interested in getting into the 'nuts and bolts' and would rather have a 'professional' do it. I have seen many members join here, learn about their particular model tractor and with the help of other members fix the problem or even end up totally rebuilding their tractor.

 

[546cowboy 301]

Actually that should be a lesson for everyone. Working on cars for many years I have run into all kinds of problems that were simple to fix once the problem was found. But I, like everyone I've ever known, sometimes tries to over complicate the problem.

In this case though, it should not have ever happened. Included in your tools should be a known good spark plug with a ground attached to it. That way you just pull a plug wire and hook in the test plug. That way you know for sure weather you have spark or not.

[WVHillbilly520H 10,373]

I know it's an older post but pinned so here's my  on a cheap diagnostic tool ....in line spark tester comes in all styles and price ranges ...picture attached...no fumbling with grounding a loose plug 

[Jayzauto 89]

GEvening Guys, I realize this is an old post, but for the sake of others in search of info, I'd like to add my .02.  I am by no means a WH Specialist, but well versed in all things electrical.  I noticed there is some confusion on modules here and testing.  Definitely keep things simple and basic, "don't overthink it" is great advice.  The adjustable spark tester is one the most valuable and basic tools that anyone that attempts their own repairs should have in the tool kit.  It will quickly verify a no/spark condition, by actually loading the ignition coils.  On modules....in their simplest forms, they are simply on/off 'switches', that will provide a ground to allow buildup of ignition coil charging.  It is an electronic version of points.  The 'Grease' supplied with ignition modules is a critical component.  As a few (sorry, new and not familiar with names), have stated, similar in function to the GM modules of days gone by.  That 'Grease' is actually called Die-electric grease. It's purpose is to ensure a good contact to the mounting base to allow heat transfer to the base.  It will help prevent corrosion from building up between the module and base.  That bond is necessary to prevent the heat buildup of the switching action, and heat is what will 'Kill' the module.  The mounting 'Screws' with star washers ensure a sound ground point. This ground point is used to ground the (-) side of ignition coil to allow coil charging.  The transistors (Switch/es) inside the module, will break that ground connection, allowing the magnetic field of the ignition coil to collapse, and induce the multiplication of power in the secondary, through the cables to jump the spark plug gap.  Other parts in the module will affect ignition timing control, as well as the input from a pick-up coil (not exactly sure where on the Onan), but represents TDC (roughly) according to camshaft position.  So in essence, the main parts will be: Pickup coil, Ignition module, Ignition coil, secondary leads (plug wires) and Spark plugs, and of course, primary wiring through the key switch.  So other than access to said components, which apparently is tougher on the Onan, testing the whole ignition system can quickly be diagnosed with a spark tester, test light( or preferably a quality volt meter) and a starter button.  If anyone would care to 'Donate" a 520, I will gladly teach quick and EZ testing procedures. 

 

GLuck, Jay 

[clydeo 2]

I couldn't get my 416-8 with an Onan P216 engine to start and tried every troubleshooting suggestion I could find with no results. When I decided to try to remove the flywheel to take a look at the Ignition Module I resorted to using a hammer on the wheel puller and still couldn't get the flywheel to move off the rusted crankshaft. After I gave up with that effort, I went back to the Ignition System Test procedure and got an indication of a spark. I reinstalled the spark plugs and the engine started. I drove the Wheel Horse to the shed and during cleanup noticed some clumps of dirt where the Wheel Horse had been parked. Close inspection of the dirt revealed an impression of what appeared to be the Ignition Module. My conclusion is that I dislodged a dirt dauber's nest from around the Ignition Module which allowed the ignition system to function correctly.

[6bg6ga 272]

Sounds logical. No need to remove the flywheel until its necessary because you can test the module simply by disconnecting it from the coil applying 12VDC to the red lead of the module, connect one lead from your meter (set meter on DC scale) to the negative lead on the module and the other lead to engine ground. Rotate the engine flywheel and if the module is good you will see the meter go to 12 volts when the timing marks line up and it will continue I believe for a partial revolution and then go to about .1 volt or so. Failure to obtain this simply means the module either has something blocking it in our case insects junk or the module is trash.

 

By the way did you take out the center crankshaft bolt when trying to remove the flywheel? Watched someone one time try to remove the flywheel without removing the bolt which resulted in some extensive cussing and red face... wasn't me. Also the pullers with the reach around jaws don't seem to work with these flywheels. I opted for the cheap Harbor Freight puller that worked like a charm.

[SAM58 30]

Good Article! 

[tbirdsteve 11]

Martin. great info, thanks. I ran my P220G on the bench for the first time since I bought the 93 520H. I only had the sellers word that it ran. It had too many issues to start when I bought it. Anyway, fixed the starter, squirted some gas down the carb, hooked up to a battery, power to the positive on coil, tested for spark, all good, then it coughed into life for a few seconds. Great, time to hook up the fuel pump and run the engine. Did that, but it wouldn't start. Realised I had hooked up power to the negative coil post by mistake. No spark now. Would you all agree that I've cooked the ignition module??

[6bg6ga 272]

There is information in the 1st post in this thread on testing the ignition module. I would suggest running a test before trying to speculate on if its bad or not.  The module is nothing more than a glorified hall effect switch. It doesn't require heat sink compound but does need the insulator for increased life.