Cool troubleshoot find

[Jpflex]

While troubleshooting a no start on a diesel generator for my company I found 2 volts from the main cable feed to starter from 12 volt battery source to ground.

I suspected a ground issue since battery was fully charged. Also nothing on generator worked and when I jumped both positive and ground jumper cable direct to starter it still spun slow.

Sure enough I found a bad negative connection clear the hell down almost to negative post so you got 12 volts showing almost at negative terminal. Something you don’t see often but text books always mention

Cut off bad, worn out carbon tracked corroded end and cleaned up all grounds and problem solved.

Another project I had similar to this was a tractor drill that had its ground completely disconnected and voltage Positive 12v showing on chassis relative to battery negative

 

[retirede]

Voltage chassis to negative post is one of the first things to check on a dead vehicle. Right after battery voltage.

 

[Jpflex]

I

Voltage chassis to negative post is one of the first things to check on a dead vehicle. Right after battery voltage.

I say this I less common because factory cables do not typically encounter this problem as they are one solid unit conductor.

The one shown is a separate cable with The ring terminal that is held together by pressure

 

[blueheels2]

Always amazes me how smart people are in this trade.

 

[retirede]

I

I say this I less common because factory cables do not typically encounter this problem as they are one solid unit conductor.

The one shown is a separate cable with The ring terminal that is held together by pressure

That’s true. I have enough older machinery and cars that I have more made-up battery cables than those with the integrated ends.

 

[xformer]

Voltage chassis to negative post is one of the first things to check on a dead vehicle. Right after battery voltage.

Old tractors had a positive grounded system.

 

[retirede]

Old tractors had a positive grounded system.

Mine aren’t. Oldest machine I have now is an IH856 which is about a 1970 model.

I had a couple 6V, positive ground that I converted to 12V. Converted to negative ground at the same time so I could use a car alternator. The nice thing about a series-wound starter motor is that it runs the right direction regardless of polarity!

 

[Jpflex]

Mine aren’t. Oldest machine I have now is an IH856 which is about a 1970 model.

I had a couple 6V, positive ground that I converted to 12V. Converted to negative ground at the same time so I could use a car alternator. The nice thing about a series-wound starter motor is that it runs the right direction regardless of polarity!

Interesting

 

[Jpflex]

Old tractors had a positive grounded system.

Heard of this and positive spark plugs but haven’t encountered them yet

 

[Jpflex]

Always amazes me how smart people are in this trade.

Not the same as being well paid. The two are not always synonymous. Companies get the most advantage out of skilled and learned professionals these days while jobs pay less and less until one day a full day of work will cover one meal

 

[blueheels2]

No argument from me. Everyone in the trades is underpaid. That’s why I started my own company, not that I’m killing it. But I’m the past 6 months I’ve made more than I ever have.

 

[ptonsparky]

No argument from me. Everyone in the trades is underpaid. That’s why I started my own company, not that I’m killing it. But I’m the past 6 months I’ve made more than I ever have.

Don't forget your Quarterly taxes. They will catch up to you at the worst time.

 

[OldBroadcastTech]

Oliver tractors had positive ground up thru the 'triple-digit' ( 770, 880, etc) series

Starting with the 4-digit series.....1600, etc< they went to negative ground.

I once watched a supposed 'Oliver Expert' burn up 4 alternators within 2 hours because he 'knew' that the 880 he was working on ( my Dad's !) had a negative-ground system. Suggestion that he open the battery compartment lid and see for himself went unheeded, in fact he got downright HOSTILE.

 

[LarryFine]

I remember reading that negative ground creates a better spark for ignition.

 

[Tulsa Electrician]

I remember reading that negative ground creates a better spark for ignition.

Never heard that one. Interesting

 

[LarryFine]

Never heard that one. Interesting

It has something to do with the direction of the spark between the center and ground electrodes.

 

[Tulsa Electrician]

Time to hit Google and read.
Thank you

 

[zbang]

in fact he got downright HOSTILE.

When the Know-it-all becomes the Know-it-none .

 

[hillbilly1]

Old tractors had a positive grounded system.

Along with being 6 volt! I converted mine to 12 volt with a GM 1 wire alternator, changing it to negative ground.

 

[hillbilly1]

Mine aren’t. Oldest machine I have now is an IH856 which is about a 1970 model.

I had a couple 6V, positive ground that I converted to 12V. Converted to negative ground at the same time so I could use a car alternator. The nice thing about a series-wound starter motor is that it runs the right direction regardless of polarity!

Just read yours, you beat me to it. I have a 601 Ford selectospeed.