Measuring electricity

A couple of months ago, I posted about a problem that I had with my tractor starting after I released the starter. The suggestions included measuring to locate the "drain" of electricity to find the problem. Now that mowing season is getting closer, I need to address the problem. What is the best tool to use to do this? Thanks

Multimeter

The problem is, you'll need one huge honkin' multimeter to measure the source of your "drain:" THE STARTER.

No other electrical component on your tractor draws nearly as much current as the starter while it's cranking the engine. It would take 15-20 headlight bulbs to even begin to draw on the battery as hard as the starter does.

Your starter probably isn't in the best of shape. It may have a shorted winding that's causing it to draw far more current than it would normally.

Had a similar problem with a starter in a Super C recently. The starter would crank the tractor fine, but the tractor wouldn't start. Swapped in a junkyard starter and viola!

I had the starter rebuilt about 3 years ago. Do you still think that is it? Would you just take it off and have it worked on without checking anything else?

If the starter is in good shape [only 3 years], look for bad connections going to the coil/ distributor. This includes everything from the ammeter up through the distributor--even the ground side of the points. You may have to run a jumper wire up to the distributor from the battery just to prove out that it will or will not start normally.
We had the SMTA act like this, & it turned out to be the wire going to the dist. was down to 3 wires left in the stranded wire where it went up over the valve cover. No explanation why this happened, but it sure caused trouble.

Well, my experience with so-called "testing" and "repair" of starters is that most don't really know what they're doing. If they apply battery power to the starter and it spins, it's "good."

There may be nothing wrong with the starter, too. Is this a 12V conversion?

A battery's voltage drops when you put a heavy load on it. While cranking, the battery could drop from 12V down to 8V. Since the ballast resistor cuts that voltage roughly in half, the coil only sees 4V, which isn't enough to get it to fire.

We've got a Super M with a TSC "high torque" starter in it (from back in the day when TSC was a tractor parts dealer, not a horse feed store). After converting it to 12V, the tractor won't start until you let off the starter. Not a big deal because the starter spins the living daylights out of the engine.

(quoted from post at 21:51:24 02/21/11) The problem is, you'll need one huge honkin' multimeter to measure the source of your "drain:" THE STARTER.

No other electrical component on your tractor draws nearly as much current as the starter while it's cranking the engine. Swapped in a junkyard starter and viola!

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It requires a good DC amp head. This is not work for the $10.00 job from Radio Shack.

One can measure voltage on both sides or connections and see if there is a drop, same at coil.

Starter amps will go up with poor connections so voltage drop is a good place to start, if connections and such are good then wory about the starter itself.

(quoted from post at 09:45:08 02/22/11) Well, my experience with so-called "testing" and "repair" of starters is that most don't really know what they're doing. If they apply battery power to the starter and it spins, it's "good."

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There are some poor re-builders out there. We still have one in my area with the old style load testing machine.

I would measure the voltage at the coil input side when points are closed so current is flowing through the coil, and compare that voltage with battery voltage. If over .2 volts difference you have too much drop through wiring, ign switch, ammeter etc. Then I would measure battery voltage while starter is cranking the engine, if below very min of 4.5 volts you have poor battery, or low battery, or if battery is good, too much current draw from starter. A battery load tester can very easily give you a good accurate estimate of how much current starter is drawing. You read battery voltage while starter is cranking engine, then you load the battery with load tester to that same voltage and read the ammeter on load tester and that will be a very good indication of starter draw. Now, how much it should draw, well, that is where the interpetation of gauge readings come into play as temp, oil viscosity, compression, all come into play. Often times, just taking a starter apart on them old girls and lubricating the bushings well help immensely. The biggest single item in a starter that causes excessive current draw is lube and bushing conditions.When you hit that starter, those magnetic fields are drawing that armature toward the side of field that is opposite polarity at that time so and it is moving away from other field winding on other side. That distance causes a reduction in magnetic forces against armature winding. If it moves enough to drag you really have problems. Rarely will you find shorted field windings or armature leakage. Good clean contact of brushs on commutator with good spring pressure and good internal connections is the usual repair along with good tight but free bushings.