[AT] [Farmall] Never heard such a bang

[Richard Walker]

Not claiming this will be causing your starting problem, but is the PTO 
disengaged?

I routinely run a log splitter off my Cub LoBoy using a PTO mounted pump 
and rear reservoir.  I usually just engage the PTO when actually 
splitting.  One morning, after just using it the day before, the Cub 
wouldn't start, not even a pop.  Was getting good spark (Pertronix 
ignition), checked ignition timing several times, it would not even kick 
on starting fluid, drained out gas for fresh, tore down carb several 
times and still nothing.  Then I towed it back to my shop to check 
compression, valve timing, etc, all of which was correct.

Baffled, I was just about ready to pull the head to check out the 
internals when I noticed the PTO lever was engaged. I'd forgotten to 
disengage it after quitting for the day and shutting the engine down.  
Duh.  Pulled the lever to the disengaged position, hit the starter 
button and the tractor started as always, within a turn or two.  Go 
figure.  The added drag of the hydraulic pump load?

Subsequently I've done more testing and what's odd is if the tractor is 
warm, it will start immediately even with the PTO engaged.  But cold, 
not even a pop until I disengage the PTO, then it starts right up.

My Cub is a '64 model, so I think that was built before safety PTO 
interlock switches got incorporated.


-  Richard


> Here's where we are at now: I dropped my spare H4 (with a new condenser)
> which throws a nice hot spark on the tractor.  Nothing: I gave up
> cranking after nearly wearing my arm off!  So I bit the bullet and
> rebuilt the original magneto: no condenser, new points.  New distributor
> cap.  The magneto is still throwing a quarter inch spark with no
> issues.  After reinstalling it, this time I received a bang.
>
> The timing is perfect: magneto impulse fires #1 terminal on the cap at
> exactly TDC.
>
> I took the carburetor apart, again.  Everything is squeaky clean. This
> is a Zenith 11115B: no main jet adjustment.  The bang proves I am
> receiving fuel into the engine.
>
> Valves are still good.  I double checked them all.  No bent pushrods,
> either.
>
> So I'm leaning towards spark.  I'm trying to decide what would burn
> up/break while the tractor is running, which would reduce power, then
> suddenly not allow it to start at all.  I'm thinking that I should at
> least get it to run (but maybe not well) even if the coil was bad.  It
> is throwing a spark all the time while I am cranking the engine.
>
> Any thoughts?  Thanks for helping solve this problem... I'll be glad to
> hear this creature run again!
>
> Ben W.
>