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

[mroberts5]

First off, sorry for the 8th post today about a tractor not starting. I tried searching .. but wasn't finding what I'm looking for.

Other than a long nagging issue of low oil pressure on startup (takes 5 sec to build pressure) the tractor has always started right up hard.
Last weekend I shut it down during some work and it would not restart.

Here is what I got : Weak Start Video

Note - this is with jumper cables to the truck. Without the cables I don't get cranking - just a light click.

Other things I've done:
Removed starter and bench tested with small 12V battery - solenoid hits and it spins right up.
Took apart starter, clean commutator and brushes. All look fine (to me).
Took apart solenoid, sand and clean start motor contacts.

What I haven't done yet:
Putting the negative directly on the starter.
Replace starter.
I have not been able to spin motor by hand yet (not it wont spin, i just cant get a wrench on it- does anyone know what size nut is on the crankshaft? largest I have is 34mm and it was still too small. You can see from the video it does turn though...)

I wonder if I have two issues? I can't understand how the starter runs fine on the bench, ok but not strong enough when jumpered to running truck and barely at all if on tractor battery...

Bad negative connection from chassis to starter?

 

[Agvg]

Dead battery?

 

[the old grind]

A little of both? Secure ground to chassis is always my starting point. Nearly half the time it's the cause of poor starter performance.

Some cable ends corrode inside at the expense of good contact. The rat-a-tat sound is solenoid contacts practically spot-welding themselves. Enough of that can ruin contact surfaces and cause weak starting after another issue is fixed.

 

[aczlan]

A little of both? Secure ground to chassis is always my starting point. Nearly half the time it's the cause of poor starter performance.

Some cable ends corrode inside at the expense of good contact. The rat-a-tat sound is solenoid contacts practically spot-welding themselves. Enough of that can ruin contact surfaces and cause weak starting after another issue is fixed.

I was just going to suggest looking at that.

Aaron Z

 

[mroberts5]

Tried jumping both positive and negative from truck to starter. A little better but basically the same.

Will try new starter...

 

[LouNY]

More likely cables or ground connections.
If you have a helper and a voltmeter,
put one lead on the battery + and one on the starter lug,
with the key off you should have battery voltage,
cranking the closer to zero volts the better more then two is a connection issue.
Using your booster cables connect one end to the starter bolts and one to the battery negative and try starting,
that will verify your ground path.

As far as jumping it off your if your battery is bad it may be taking everything your booster cables are passing.
Many of the current cables are almost worthless.

 

[radios1]

Tried jumping both positive and negative from truck to starter. A little better but basically the same.

Will try new starter...

that is possibly the problem!. I ran into that a while ago, and it turned out the starter needed service, a new high torque starter cranked over better than new!..

 

[fried1765]

Tried jumping both positive and negative from truck to starter. A little better but basically the same.

Will try new starter...

Have you taken your battery to NAPA (or similar) for a load test?

 

[the old grind]

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.

 

[k0ua]

No start issues: If you took 100 cases of no start, about 1 percent would be starter related. Yep 1 out of 100 would be something wrong with the starter. The actual starter being the culprit is so rare that you can practically ignore it. Sure it happens, but not often. Bad batteries (high internal resistance), High resistance inside of cables (due to hidden inside corrosion) and loose or high resistance connections are the normal and prevalent culprits. You can find them all with a voltmeter and a helper.