International 786 charging help

[jowens1185]

I've got a friend of the family that I'm looking at their international 786 that runs for a small amount of time then dies and won't restart. When it dies acting like the alternator isn't charging correct because to restart, the batteries need to be recharged. So I've checked voltage at the alternator while running and get nothing. Also have checked at the batteries and the voltage on each battery is just slightly under the voltage before start.
I'm gonna have the alt tested but my question is if my alt is good where do I go from here. I bought a manual and the only wiring diagrams it has in it is for ac and lights no charging system diagrams.
Thank you in advance.

 

[used red MN]

Hello jowens, welcome to YT! Check the voltage at the alternator with the engine off, should always show battery voltage. Is this a gas or diesel? If a gas engine the spark maybe messing with your cheap meter.
Wiring diagrams On the x86 those foldouts are separate links.

 

[jowens1185]

I will try that. It's a diesel. Thanks

 

[Jim.ME]

I've got a friend of the family that I'm looking at their international 786 that runs for a small amount of time then dies and won't restart. When it dies acting like the alternator isn't charging correct because to restart, the batteries need to be recharged. So I've checked voltage at the alternator while running and get nothing. Also have checked at the batteries and the voltage on each battery is just slightly under the voltage before start.
I'm gonna have the alt tested but my question is if my alt is good where do I go from here. I bought a manual and the only wiring diagrams it has in it is for ac and lights no charging system diagrams.
Thank you in advance.

Welcome to the forums.

You should post the voltage readings when you give results.

You need to identify what the manufacturer of the alternator is and its details. From the parts book it appears it should be a Delco type 3 wire. However, sometimes things get changed over the years, so it is best to give all the info of what is there.

Depending on the alternator, there is a way to check full output while on the tractor. But before doing that we need to see the results of what used red MN has asked you.

 

[BarnyardEngineering]

I've got a friend of the family that I'm looking at their international 786 that runs for a small amount of time then dies and won't restart. When it dies acting like the alternator isn't charging correct because to restart, the batteries need to be recharged. So I've checked voltage at the alternator while running and get nothing. Also have checked at the batteries and the voltage on each battery is just slightly under the voltage before start.
I'm gonna have the alt tested but my question is if my alt is good where do I go from here. I bought a manual and the only wiring diagrams it has in it is for ac and lights no charging system diagrams.
Thank you in advance.

First, please define "a small amount of time." Minutes, hours?

Starting the tractor does not completely drain the batteries, and once the engine is running, it requires very little battery power to operate the gauges. You should be able to start the tractor, immediately shut it off, and start it again, over and over, dozens of times before the battery goes dead.

How does the engine shut off normally? It should shut off by pulling the throttle lever down to the stop position if I'm not mistaken. The only reason the tractor needs ANY electrical power at all after it is started is if it turns off with the key. That means it has an electric solenoid on the shutoff plunger. Otherwise you can turn the key off, take the batteries out, and run the tractor all day once it is running.

With a mechanical shutoff, if the engine is just quitting after "a small amount of time" you have fuel flow problems. The electrical issues are a completely separate, coincidental, problem.

 

[jowens1185]

First, please define "a small amount of time." Minutes, hours?

Starting the tractor does not completely drain the batteries, and once the engine is running, it requires very little battery power to operate the gauges. You should be able to start the tractor, immediately shut it off, and start it again, over and over, dozens of times before the battery goes dead.

How does the engine shut off normally? It should shut off by pulling the throttle lever down to the stop position if I'm not mistaken. The only reason the tractor needs ANY electrical power at all after it is started is if it turns off with the key. That means it has an electric solenoid on the shutoff plunger. Otherwise you can turn the key off, take the batteries out, and run the tractor as long as you want.

With a mechanical shutoff, if the engine is just quitting after "a small amount of time" you have fuel flow problems. The electrical issues are a completely separate, coincidental, problem.

It will run 30 minutes to an hour and dies on its own. Go to restart and acts like dead battery no crank.

 

[BarnyardEngineering]

It will run 30 minutes to an hour and dies on its own. Go to restart and acts like dead battery no crank.

Check voltage on the batteries. If it's 12V or higher, they will crank the engine. Should be 12.6-12.7 after sitting overnight when fully charged. I'd suspect bad connections first, starter second in that situation.

How does the tractor shut off? Key, pull knob, or throttle handle?

If the batteries are truly going flat dead in less than an hour, you've got a serious dead short somewhere, which you should be able to at least smell, if not see in the form of smoke, or the batteries are totally pooched.

 

[jowens1185]

They stay charged over night. The tractor starts fine when batteries are charged. The tractor starts and runs for x amount of time then dies and won't restart immediately because batteries are drained. It acts like in a car when the alternator goes bad will run basically until the battery goes dead.

 

[BarnyardEngineering]

They stay charged over night. The tractor starts fine when batteries are charged. The tractor starts and runs for x amount of time then dies and won't restart immediately because batteries are drained. It acts like in a car when the alternator goes bad will run basically until the battery goes dead.

You've confirmed the batteries are actually dead, or are just assuming the batteries are dead because the tractor won't crank?

I'm very familiar with these tractors and there isn't anything on the tractor that can possibly run down the batteries in an hour or less. Also as I've stated at least once now, the tractor doesn't need any electrical power whatsoever once it is started.

 

[used red MN]

Barnyard, it may be a cab tractor and he is running a heater blower. He said it is a “friend of the family” so he probably can’t run out back and do the checks we are asking for. Again, if the large alt terminal on the back has no power all the time then there is a wiring problem.

 

[Roger Tomfohrde]

Sounds like a fuel problem in the in back ground as a diesel should stay running.

 

[rustred]

I've got a friend of the family that I'm looking at their international 786 that runs for a small amount of time then dies and won't restart. When it dies acting like the alternator isn't charging correct because to restart, the batteries need to be recharged. So I've checked voltage at the alternator while running and get nothing. Also have checked at the batteries and the voltage on each battery is just slightly under the voltage before start.
I'm gonna have the alt tested but my question is if my alt is good where do I go from here. I bought a manual and the only wiring diagrams it has in it is for ac and lights no charging system diagrams.
Thank you in advance.

u have 2 problems going on. once a diesel tractor is running , its not going to stop because of dead batteries. better get on your fuel filters changed. that should be a manual shut off on the pump by lifting the throttle all the way up. be a lot of help here if you posted your voltages after your checks. there will be readings either under 12 volts or over 12 volts or around 14.5 charging. plus just checking the voltage on a battery does not mean the battery is good. you need to load test it. it can show full charge and still be no good , meaning a couple cranks enough to start the engine and thats it. if the alternator is not putting out then it needs to be rebuilt of replaced with one. 90 percent of the time its the brushes are worn out. you say you checked the alt. and get nothing,... what does that mean, 0 volts or 12 volts? see we need readings.

 

[MARK ROBKE]

I've got a friend of the family that I'm looking at their international 786 that runs for a small amount of time then dies and won't restart. When it dies acting like the alternator isn't charging correct because to restart, the batteries need to be recharged. So I've checked voltage at the alternator while running and get nothing. Also have checked at the batteries and the voltage on each battery is just slightly under the voltage before start.
I'm gonna have the alt tested but my question is if my alt is good where do I go from here. I bought a manual and the only wiring diagrams it has in it is for ac and lights no charging system diagrams.
Thank you in advance.

If you mean there is no voltage at the alternator big/ battery terminal -meaning zero volts-, is there any voltage there when engine is off? If the wire is dead, it goes back to the batteries via a positive starter terminal. I would locate that wire and check continuity. Or maybe it is broken or not connected at the starter because someone left it off when replacing the starter. Mark.

 

[MARK ROBKE]

If you mean there is no voltage at the alternator big/ battery terminal -meaning zero volts-, is there any voltage there when engine is off? If the wire is dead, it goes back to the batteries via a positive starter terminal. I would locate that wire and check continuity. Or maybe it is broken or not connected at the starter because someone left it off when replacing the starter. Mark.

I had a 1086 that had that problem-can't remember the exact fix though. Mark.

 

[BarnyardEngineering]

Barnyard, it may be a cab tractor and he is running a heater blower. He said it is a “friend of the family” so he probably can’t run out back and do the checks we are asking for. Again, if the large alt terminal on the back has no power all the time then there is a wiring problem.

Even so, the cab heater won't completely discharge the fully-charged batteries to flat dead in 30 minutes to an hour. Common sense would also be to turn off anything electrical if you were having battery problems.

Still, once the tractor is running, the state of the batteries, condition of the wiring, functionality of the alternator, don't matter because the tractor doesn't need electricity to stay running.

 

[used red MN]

Even so, the cab heater won't completely discharge the fully-charged batteries to flat dead in 30 minutes to an hour. Common sense would also be to turn off anything electrical if you were having battery problems.

Still, once the tractor is running, the state of the batteries, condition of the wiring, functionality of the alternator, don't matter because the tractor doesn't need electricity to stay running.

Do these tractors cut the fuel by moving the throttle back past the idle stop like many previous IH models did? If so I agree as you and others said the it should stay running no matter. I agree he has two problems. He hasn’t been back to the forum since halfway through the day he posted this unless he viewed it without signing in. Everything is a moot point until he comes back.