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Discussion Starter · #1 ·
Hey guys. My recently aquired L will not start. We've done all the little things you would to a mower that has sat for a long time, oil, clean tanks, new fuel filter etc. We've already determined the starter is no good. We are trying to start it with a strap.

We are getting no spark on the new plug. we disconnected the kill switch and still nothing. what do you recommend?
 

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Right.

You can clean the points in place, but you may find it easier to take the mag off. Remember the orientation on the drive.

If cleaning (and maybe gapping) the points doesn't do it, you can get a set of points/condensor on ebay or from Richard or other suppliers.

It's also possible that the coil has shorted out, but that seems to be a pretty rare failure mode on these things. I vote for points.
 

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Discussion Starter · #4 ·
thanks guys.

We took the starter apart and somehow got it to run. Still no spark. Took the cover off the coil and tried to clean the points, still no spark.

I'm going to get a set of points and condenser from the gravely dealer and go ahead and get a carb gasket/rebuild kit while we're at it.
 

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Are the points gapped somewhere close to the right value? If they're not opening or not closing, that would do it too.
 

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Discussion Starter · #6 ·
The points were opening and closing but not sure if it were the proper location. We have feeler guages but have already put it up for the night. We are still money ahead seeing that we got the starter to run!

Hopefully the gravely dealer will have the gaskets/point set in stock. I want to hear this puppy sing ;)
 

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Mark the mag drive shaft(cam) and the mag itself so you will know how to line it back up when you put it back. Take the mag off,2 screws on the bottom, mount it on a vice, put the spark plug with in and a spark plug and ground the plug. Some one told me it is not good to spark a mag without grounding it until I find out other wise that is what I'll do. Put a vice grips onto the back and check to see if the impulse mechanism is catching all the time. I have a mag that catches sometimes and sometimes it won't. Couldn't get it to run, no spark, put new points, condenser, nothing. It would spark most of the time on the vice but not on the machine. I put another mag on the machine it stated right up.When you have it on the vice it is easy to clean and gap the point too. Check a different wire and spark plug too.
 

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Some one told me it is not good to spark a mag without grounding it until I find out other wise that is what I'll do. Put a vice grips onto the back and check to see if the impulse mechanism is catching all the time. When you have it on the vice it is easy to clean and gap the point too. Check a different wire and spark plug too.
You are right. snapping a mag without the spark plug wire being grounded is bad for the magneto. I do pretty much the same as you do. Mount it in a vice, wire it to a spark tester that is grounded to the vice. I have a c clamp with an extra coupling with an old fiber washer glued to it to turn the mag. It gives me good control and insulates me from the mag.
 

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Discussion Starter · #10 ·
What is the proper plug and gap if you can recall? I believe the manual calls for an Autolite TT10 is that correct? I think the one in it was like an 812 and we just replaced it with the same. Could that cause the issue if it's the incorrect plug. I'm also suspicious of the plug wire. It doesn't seem to fit tightly into the coil........
 

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What size socket/wrench do you use to remove the plug? Does the plug go on an angle or straight up/down? There are two sizes.
Clean the hole on the mag cap, I use a gun bore brush, clean the wire end and spread it out if need to make a tight fit. Do you have another wire and plug you know that works to use on the test?
Have you tried on the vice? Is the impulse working? Arcam shows a good picture of how to do it.
 

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Discussion Starter · #12 ·
Plug goes straight in top. Hwres some pics of the tractor:

http://www.mytractorforum.com/showthread.php?t=143379

I'll see what spark plug wrench we were using when I get down there.

My father in law is convinced it was sunk or in a flood at some point. He thinks this because of the amount of corrosion was inside the starter. We wore brushed it and it's now running like a top!! Oil was fine when drained. Not milky at all and very clean. I don't see any evidence of drowning........

He piced up some points and condenser at NAPA but they were incorrect. I'm gonna grab a new plug wire on the way down and make sure we have the correct plug in. Haven't tried anything on the bench yet. I don't have known good stuff either.......

Thanks for halls help ;)
 

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H10C. Do yourself a favor and take the mag. off, takes 5 minutes. You may need a short 9/16 wrench to get one of the bolts without taking the wheel off. Get an idea in you eye what .020 point gap looks like as opposed to using a feeler gage, which can contaminate the points with oil. They must be absolutely clean. You can turn the mag with an adjustable wrench on the drive coupling, you only have to go back and forth enough to engage the impulse coupling, not a whole turn. Hold a screwdriver between the coil terminal and the mag housing, you should have a spark jump almost a 1/2" when all is good. Make slight changes in the point gap to achieve this, and you're good to go. Set the timing so the mag fires just before TDC.
 

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Discussion Starter · #16 ·
H10C. Do yourself a favor and take the mag. off, takes 5 minutes. You may need a short 9/16 wrench to get one of the bolts without taking the wheel off. Get an idea in you eye what .020 point gap looks like as opposed to using a feeler gage, which can contaminate the points with oil. They must be absolutely clean. You can turn the mag with an adjustable wrench on the drive coupling, you only have to go back and forth enough to engage the impulse coupling, not a whole turn. Hold a screwdriver between the coil terminal and the mag housing, you should have a spark jump almost a 1/2" when all is good. Make slight changes in the point gap to achieve this, and you're good to go. Set the timing so the mag fires just before TDC.
Thanks for the pointers. The tractor is at me father in laws now so he'll be working on it until the weekend. I work nights and he works days. I'll relay the info to him.

Thanks guys!!!!
 

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Discussion Starter · #17 ·
Still nothing......

I've installed new points and condensor, gaped and tried again. Still no spark. I'm trying to rig something up to bench test it and go from there.

I'm getting kinda frustrated............. :banghead3:banghead3
 

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Still nothing......

I've installed new points and condensor, gaped and tried again. Still no spark. I'm trying to rig something up to bench test it and go from there.

I'm getting kinda frustrated............. :banghead3:banghead3
Cneck and make sure that the terminal for the kill tab/button isn't grounded to the case.
 

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http://www.sacskyranch.com/eng174.htm Here is a link to a short tutorial on potential mag problems. This discusses magnetos as used on airplane engines, the theory is the same, Gravely's have one cylinder vs 4 or 6 on an airplane. Low or no spark can be caused by a shorted coil or weak rotor magnet. Rotating the mag with no place for the voltage to go (grounded plug) electrically stresses the coil potentially resulting in a shorted coil. When rotating the mag by hand resistance will be felt at the point of maximum induced magnetic field. The points should open just past this rotational point for maximum spark. This is "E" gap (magneto internal timing) and as is usually set with a jigged tool for the correct rotational point. The purpose of the impulse coupling is twofold. It snaps the magneto thru it's firing position to provide a spark at slow cranking speed and to delay (retard) this sparking closer to TDC (after TDC?) to prevent kickback. The impulse coupling is disengaged upon starting. The rotational distance between impulse engagement and impulse dis-engagement is the lag angle. Good luck, Jim
 
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