Hand start John Deere 1936

If she starts very very easy when pulled and then runs and idles and pulls fine, but is hard to hand start, the things I suspect in order are as follows:

FIRST, IGNITION RELATED POSSIBLE CAUSES

1) The mag impulse spring is weak or it and the wind and trip assembly are not working at all.

2) When you rotate the flywheel, each 180 of crank rotation (unless its a gear reduction mag) you should hear a loud distinct SNAP when the mag fires. Do you????? ? If its only a faint dull clunk, the spring is windign and tripping at least, but maybe shes (the spring) weak causign a weak spark causign hard starting.

3) If she dont snap at all, the wind and trip is not working, even though she could still run fine.

4) If no snap, remove the mag and at its rear coupler, clean and blow out and light lube and WD 40 etc and make sure the trip dogs are coming out to engage. They have to come out to engage and wind the spring, or shes not gonna snap and fire at cranking speeds.

5) Now, if the trip dogs work and the spring winds and engages and makes a loud sharp snap, its time to check the starting spark.

6) Remove the plugs and have their wires attached and them up against the frame for a ground, and rotate the flywheel to insure BOTH plugs produce a visible blue and NOT a faint thin wimpy yellow spark. If a faint spark, inspect the points for proper gap and see that they are NOT gray oxide coated or burned or pitted, and if so, replace them and check the spark then and see if she hand starts better. Are the plugs in good shape, if not, replace them, maybe try Autolite 3077.

7) The wires should be wire core and NOT auto carbon suppressor types, and the cap and rotor must be clean and moisture free and contain no cracks or carbon traces.

SECOND, OTHER POSSIBLE PROBLEMS

8) If the engine sets and the rings and/or cylinders are worn excessively and the oil seal at the rings drains away, at initial hand cranking she has low compression and vacuum and is hard to hand start. Remove the plugs and squirt oil in the holes and rotate her to oil the rings up and see if she starts better then??? Also, a dry and wet compression check or if she blue smokes out the stack or has excess crankcase blow by can indicate those type of hard to start problems.

9) You may want to remove the air intake and insure the choke butterfly plate is tight on its shaft and stays put relative to where you set it.

SUMMARY, if she is not an oil burner, has no excess blow by, the choke works fine, but shes hard to hand start yet pull starts n runs fine, its a good candiate for either a weak mag spring (dull clunk versus a loud snap) but if not snappign at all, then a defective or stuck/corroded trip dog assembly at the rear of mag where she mates with the governor shaft.

Good luck, God Bless, let us all know.

Post back or e mail jmn50@msn.com any questions and we will all try our best to help you.

John T

~The first is the mag.. as Frank said, turn the flywheel & listen for the mag to snap or click loudly.. If there is no snap you have probably found the problem.. Mark the mag to the governor with a paint mark, then pull he mag off the tractor & check for a rusted impulse cup, rusted or broken levers, or dried up oil & gunk.. Then look for a broken impulse spring.. If you hold the mag with the impulse cup facing you & the mag oriented in the same direction as it is mounted in the tractor, turn the impulse to the left & you should feel it hang up then snap as the levers catch on the stop ring then let go.. If the impulse isn't working & you can't figure out why just post back or E-Mail..

~If the mag snaps you aren't out of the woods yet?.. If the mag snaps when you turn the flywheel that means the impulse is working but it still could have a weak spark... To test for that, take an old [known good] spark plug & open the plug gap to 3/16", then install that large gap plug in one plug wire at a time & lay it on the engine block [leave the original plugs in for slower cranking as in starting] ... If your mag is functioning & sparking correctly you should see a bluish spark jump that 3/16" plug gap on every other snap of the mag.. If it's intermittent, yellow, or weak looking you have mag problems so post back or E-Mail with your mag make & model..

~The second problem could be low initial compression at hand cranking speeds... If the mag if functioning good per the above then give it a cold hand cranking compression test.. You might also try adding some oil to each cylinder before trying to start as that will boost the hand cranking compression.. In some cases putting some 2-cycle oil in the gasoline can improve the hand starting compression enough to help hand starting... Low initial hand starting compression can be caused by excessive ring side clearance, once the engine is turned over faster [by pulling] the rings can't bleed the compression off as fast as the pistons are moving so it will start..

~You could also have a carb or choke problem but address the above first & see if your problem can be isolated... It probably wouldn't hurt to pull the carb air inlet elbow & visually look at the choke plate to see if it is closing & not bent [I have seen a few bent ones over the years]..

~I doubt you have a timing problem as it starts right up when pulled... You might just want to check it to see if it is off though... To do that, just turn the flywheel in the starting direction & listen for that mag to snap,, when it snaps the L/H impulse writing on the flywheel should be lined up [or at least close] to the timing mark on the main case [at 3 o'clock directly behind the flywheel & even in height with the center of the crankshaft..

~Try some of the above & post back or E-Mail with any questions...

JDClooney@aol.com

I'm not a magneto guy, but I wonder if your mag's impulse coupling is working. It effectively rotates the mag very quickly during hand cranking when the rpm of the engine is pretty slow and the mag can't generate sufficient electricity to make a good spark. The impulse coupler winds a spring that "kicks" or spins the mag really fast through that portion of the spark cycle to give you a good spark to get it started at hand cranking speed. Now there's more to it than that, but you get the picture. If you turn your engine over really slow, until the flywheel lines up with the LH Impulse mark, does the mag "trip"? If so, that's the impulse. It's tripping ok, check the timing, and also the spark.

I'd check that first, because if you are not getting the wind up and trip of the impluse, you'll crank till you're blue in the face!.

Frank