WD-9 Magneto troubleshooting help?

tractorsam · Oct 27, 2014

I'm working on a WD-9 with a magneto that used to start alright on gas but now won't even cough. I know just about enough to be dangerous when it comes to magnetos. So far I've disconnected the ground wire that goes up to the manifold, removed the coil wire where it goes into the cap (no spark) cleaned the points which are opening and closing, verified they're functioning electrically, removed the condensor and coil, checked for chafed or shorted parts (nothing obvious), verified there's enough magnetism left to stick a screwdriver to either side of where the coil sits. I'm now stumped and not sure where to go, any help would be great, thanks, Sam

Bob · Oct 27, 2014

http://www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/GSS-5035%20Service%20Manual%20Magnetos/index.html

(Link to factory mag manual. You'll have to cut and paste 'cuz a direct link to that site won't "take" at this site.)

teddy52food · Oct 27, 2014

Get that condenser tested. If it checks out good then get the coil tested.

Fatamus · Oct 28, 2014

Condenser sounds like the culprit, coils usually start cold and go bad quickly (like it is out of time then stop working) when they worm up. Also look at the plugs and plug wires/coil wire and connections. Plugs go south relatively fast if the carb is out of tune on the TD,WD 9's. They are a very hot plug range Um D49 D I think. Spendy puppies for the right plugs. .23 thousands of an inch is proper gap I think.
ALSO make sure the butterflies are working.. reach up and flip the L shaped lever up and down it should be springy and spring back up. if it don't spring back up by itself spray some Marvel Mystery Oil on the linkage on the that side of the motor. I had the same trouble with my TD9 and LOOK FOR OBSTRUCTION in behind the manifold and linkage..I had to use my cell phone to take a picture and found an old starting fluid cap stuck between the manifold and shaft that operates the butterflies.
You can check the condenser by arcing it across a battery then have someone touch both ends, OR you could touch both ends, OR use a tester but it will only spike the needle... Where is the fun in that???

Good Luck
Fat Dan

Fatamus · Oct 28, 2014

After cranking over for awhile are the plugs wet? If not look to at carb. On older mags with old condensers the spark might be blue and hard to see in the light. It don't take much spark to fire the fumes. I just took the mag off and held onto the coil wire spun it over by hand and felt a tingle, that was not enough to fire off. but if the mag kicks the puppy water out of you... well the mag is fine.
The mag off the 46 TD9 motor grader had a bad condenser so I grabbed the mag off my 41 T9 crawler which had a kick. SOMETIMES this happens; the condenser holds a charge somewhat like a D cell battery, the difference is the condenser dumps it's charge all at once. If left connected the D cell may corrode likewise the condenser can corrode too.
good luck
fat dan

gene bender · Oct 28, 2014

Are you sure the rotor is pointed at the tower plug where wire goes to the plug when it fires.

teddy52food · Oct 28, 2014

He has no spark coming from the coil.

WD-9 Magneto troubleshooting help?

tractorsam

Well-known Member

Bob

Well-known Member

teddy52food

Well-known Member

Fatamus

Member

Fatamus

Member

gene bender

Well-known Member

teddy52food

Well-known Member

Similar threads