NH 1920 Weak Starter? Barely Cranks, Won't Turn Over

[mroberts5]

all good points.

I will try one more time w/o tractor battery connected.

Also, I'm not very experienced with starters, but did notice the mica gaps on the commuter were shallow. Like I said, I didn't connect the dots as wrong at the time.. I'll pull back off and try cutting them down. have to see what I have for a very thin kerf blade. maybe I'll just use a utility knife? Worse case I screw up an already not working starter...$80 amazon starter on the way anyway...

 

[radios1]

all good points.

I will try one more time w/o tractor battery connected.

Also, I'm not very experienced with starters, but did notice the mica gaps on the commuter were shallow. Like I said, I didn't connect the dots as wrong at the time.. I'll pull back off and try cutting them down. have to see what I have for a very thin kerf blade. maybe I'll just use a utility knife? Worse case I screw up an already not working starter...$80 amazon starter on the way anyway...

also, make sure the front and rear sleeve bearings are not worn, and are greased up!. either of those conditions can cause the starter to slow down, and draw more current than it's supposed to!.

 

[k0ua]

When you get the new starter installed and it still is draggy starting, come on back and we will go over how to fix the problem again with a voltmeter and a helper.

If a new starter fixes the problem, you can color me very surprised.

 

[the old grind]

... I will try one more time w/o tractor battery connected.

Also, I'm not very experienced with starters, but did notice the mica gaps on the commuter

Without a battery connected by good ends you'd be lucky to get enough current to the starter using jumper cables.

Any undercutting of the commutator is enough. Gouging the copper alloy can shred brushes in a hurry, so polich it if you don't true it on a lathe.

If your battery is in bad enough shape it can compromise or reduce starting energy when connected and jumped.

So along with what James is getting at I'd swap out a battery and connect it properly before I'd blame and replace a starter. Terminal adapters would allow temporary mod if yyou borrow from car or truck.

 

[k0ua]

The very first thing to do is put a volt meter on the battery POSTS. NOT the battery cable terminals but the posts themselves, have the helper start the tractor, anything less that 10 volts on the battery posts during the cranking is a battery failure. High resistance inside the battery. Then if that looks good move to putting the leads on the battery cable clamps. What do you read here? Place meter across the single battery cable ends. Positive cable first, What voltage drop do you get when attempting cranking? anything over a fraction of a volt is a bad cable. Do the same for the negative cable, then move out othe one lead to the frame, do you develop a voltage across the battery ground cable and the frame? If so, there is your trouble. Battery cables and their associated clamps and screw terminals are supposed to be a shorted piece of wire with a VERY low resistance, therefor voltage should not develop between their ends. likewise the connections to their clamps and screw terminals should be very low resistance connections. Battery cables are often a source of high resistance joints in the starting system. Batteries may fail more often than cables, but not by much. Defective battery cables look just fine by casual inspection. If you pull on them firmly the will sometimes come apart. And they are often very full of green copper sulphate caused by the presence of sulpheric acid fumes attacking the copper inside of the outer jacket. Again. Tractor cranking issues are very seldom the fault of the starter itself.

 

[k0ua]

The shotgun approach to servicing anything is often a huge waste of money and time. For instance. "my tractor wont crank". I think I will try replacing the starter. WHY? Why not buy a new battery and replace it? You stand a far better chance of that fixing the problem than the starter. Why not try replacing both battery cables? You stand a far better chance of that fixing the problem than the starter. Why not replace the starter relay or the starter solenoid? All of these are much more likely the problem than the starter. Then after all of that has failed to fix your problem the buy a starter. Why start with the starter first? It is the least likely thing to go wrong. And why start replacing ANY parts at all without first forming a hypothesis of what is wrong, and then testing that hypothesis. "Shotgunning " is the absolute worst way to solve any electrical or electronic problem.

You can start taking your measurements at the starters input post if you like you don't have to start at the battery, but tell me when you helper is cranking or attempting to crank the tractor, what voltage did you measure at the starters input post (big red wire) to ground? Don't know?.. Then find out. Don't start ordering starters or ANY parts, and don't start taking things in to the auto parts store either. Find out whats wrong first. All you need is a voltmeter and a helper and some instructions or experience. You don't need any wrenches, you don't need any parts, and the simple checks I am telling you about take a few seconds. It will fix 99% of problems.

OK, sure it could be a "draggy" starter, I will give you that,. NOT likely, but possible. Do you have a clamp on DC current meter you can measure the starter current with when your helper cranks the tractor? Tell me what that starter current is. Is it excessive, or ridiculously low? Two separate things and two separate conclusions. After you have formed your hypothesis and tested that hypothesis, THEN and only then get the wrench. It is always best to do a "double blind" test. In other words test from two different points of view. If the voltage really sags on the battery but the starter current is really high, it COULD be a bad starter. Wrench off the starter and take it in and have it tested. Double blind test.

You need to have an understanding of the relationship between voltage, current and resistance.

 

[k0ua]

Again, I will be very surprised AND very pleased that you guessed right and the starter actually fixes the problem. I will be very happy to hear that I was ...wr. wr...wro.. wrong.
I am not so "full of myself" to think that I have all the answers all of the time. But I do find more acorns that that blind hog.

 

[kirkawilson]

Relay parts replacement shown on post #22 in this link worked for me: https://www.tractorbynet.com/forums...rating/404047-ford-1920-not-starting-not.html

 

[fried1765]

It's easy to say we 'proofed' the brushes and commutator, but sometimes 'undercutting' the latter is ignored ... and often unwisely so.

"Load testing" batteries and starters isn't always easy, but can tell us a lot. I always hope that a fellow member can diagnose a problem w/o shot-gunning $$ into a misguided assumption vs recognizing what's truly amiss.

Y'know, 20-series Ford/NH tractors are 'iffy' and might best be sold to myself for 'cents on the dollar' before it's too late. :laughing:

I'd be happy to drive down from MI to pick up that 1920 and take on whatever 'fixup' it needs.

Yup!
I absolutely hate my 1060 hour 1920.
Sure wish I could find somebody like you, just wanting to take it off my hands.