Zd21 diesel not cranking and wire melting

[mojoman1963]

I have a Kubota zd21 diesel 60 inch zero turn. What is happening is the starter doest always engage. Sounds like the solenoid is bad it will spin but not engage the starter. Then sometimes it will very shortly engage then spin freely. The other issue is if it does crank I noticed a wire melting coming up from the starter then it slowly cranks over like the battery is dead. I have a brand new fully charged battery. Any help will be greatly appreciated. Thanks

 

[Runs With Scissors]

Kind of a long shot, and I have no direct knowledge of your machine, however I have seen in the past on car engines occasionally if the starter spins but only "sometimes" catchs the flywheel, there could be missing teeth. (on the flywheel)

I'm unsure on how to check for missing teeth on your machine though.

The more likely cause is some sort of connection/ground problem I would bet.

For the slow/intermittent cranking I would start off by cleaning all grounds and closely inspecting battery/wiring connections. You would be surprised at how many time this fixes starting problems.

 

[GreensvilleJay]

step one..get the wiring diagram located in the WSM !

now.... how old is it ? IS there ANY corrosion on either battery cables ?

'wire melting' is due to excessive current,usually caused by poor connections. All 'melted' wires have been compromised, to replace them.

 

[Pawnee]

My bet is that you need a new starter motor.

 

[GeoHorn]

It sounds/reads to me of an internally-shorted starter. Replace the starter AND the damaged wiring.

 

[Ktrim]

Lead to starter getting hot is a sign of starter pulling too many amps or bad ground connections

 

[Soopitup]

There's some misconception here.

The solenoid doesn't spin. It's simply a large switch that controls a large amount of current.
The solenoid is controlled by a small amount of current from the ignition switch.

When the ignition switch closes it allows low current to flow and close the solenoid.

When the solenoid closes it allows large current to flow and spin the starter motor.

Which wire is melting? Small wire from the ignition or large wire from the battery?



Nothing else changing, amps can only go up if resistance goes down.
If resistance goes up, amps HAVE to go down.

A bad connection or corroded wire adds resistance.

Amperage CAN'T increase if there's a bad connection or corroded wire. It HAS to decrease.

If you lower the resistance (a short), then amps go up.

What happens is the added resistance becomes a load.

Loads "absorb" voltage. Which creates heat.



There's either a short in the solenoid or starter motor, or there's a corroded/damaged wire/connection.

If there's a short, most of the wire will usually melt.
Short in the solenoid will melt the wire from the ignition switch.
Short in the starter motor will melt the wire from the battery.

If there's damage/corrosion it will start melting closest to the point of corrosion/damage.


From what the OP is describing, it sounds like the starter isn't getting enough voltage, which means corrosion/bad connection.
Considering how bad it is, there's a good chance the solenoid itself is also damaged (not enough voltage creates a weak connection at the switch, which damages it).

Wiring obviously needs to be replaced. Probably the solenoid (whole starter if it's part, or at least the contacts inside the solenoid) as well.

 

[GeoHorn]

Lead to starter getting hot is a sign of starter pulling too many amps or bad ground connections

A bad ground connection will result in REDUCED current-draw…not increased…therefore unlikely to overheat a power-supply wire. An electrical SHORT however, will overheat a power supply wire if it’s unprotected (like many starter-power-cables are.)

 

[jaxs]

Enough already!
Bad,loose and corroded electrical connections have been discussed on this forum several times a day ,everyday for years. It is law,not opinion , not theory , not hypotheses, it is an established law of electricity that will never change regardless of weather or who is in The Whitehouse.

In view of the fact "CLICK no start" and other electrical problems are brought here daily for help,it should be priority for those who comment that help seekers get correct information WITHOUT confusing statements being injected. To that end can we unanimously agree which of the below is correct? My goal is to end the practice of people interjecting augment which does nothing but confuse members looking for answers.

So which of the following is undisputable truth,,,THIS or THIS ?

The more likely cause is some sort of connection/ground problem I would bet.

For the slow/intermittent cranking I would start off by closely cleaning all grounds and battery/wiring connections. You would be surprised at how many time this fixes starting problems.

IS there ANY corrosion on either battery cables ?
'wire melting' is due to excessive current,usually caused by poor connections.

Lead to starter getting hot is a sign of starter pulling too many amps or bad ground connections

A bad connection or corroded wire adds resistance.
What happens is the added resistance becomes a load.

There's either a short in the solenoid or starter motor, or there's a corroded/damaged wire/connection.
From what the OP is describing, it sounds like the starter isn't getting enough voltage, which means corrosion/bad connection..

A bad ground connection will result in REDUCED current-draw…not increased…therefore unlikely to overheat a power-supply wire.

 

[Soopitup]

Enough already!
Bad,loose and corroded electrical connections have been discussed on this forum several times a day ,everyday for years. It is law,not opinion , not theory , not hypotheses, it is an established law of electricity that will never change regardless of weather or who is in The Whitehouse.

In view of the fact "CLICK no start" and other electrical problems are brought here daily for help,it should be priority for those who comment that help seekers get correct information WITHOUT confusing statements being injected. To that end can we unanimously agree which of the below is correct? My goal is to end the practice of people interjecting augment which does nothing but confuse members looking for answers.

So which of the following is undisputable truth,,,THIS or THIS ?

A bad connection or corroded wire adds resistance.

What happens is the added resistance becomes a load.

These are both indisputable truth.
If you think they're not you need to go back and freshen up on your electrical theory.....

There's either a short in the solenoid or starter motor, or there's a corroded/damaged wire/connection.

These are the potential things causing the OPs problem. There's a small chance something else is, but I doubt it.
So not indisputable truth per se, but a true statement.

From what the OP is describing, it sounds like the starter isn't getting enough voltage, which means corrosion/bad connection.

The first half (bold)wasn't stated as truth, merely a guess based on what the OP wrote. And very clearly a guess (sounds like?....).
The second half is the cause, IF the guess is correct.
IF my guess was correct (not enough voltage), the cause would most likely be correct.
So, once again not indisputable truth, but a true statement.
Though it would have helped if I had clarified that I was guessing the root cause of the problem. And that more information would be very helpful.

It's hard to tell exactly what's going on over the internet. Especially when inexperienced people are posting and leaving out critical information.

Most starters have 2 wires coming off them. A wire for the solenoid and a wire for the starter motor.
Which wire is melting?
Where is it melting?
How bad is it melting?
Is the solenoid part of the starter? Or a separate part?
Is the wire touching anything else? Shorting to it instead of through the starter?

The root cause definitely could have been a shorted starter motor or solenoid.
It also could have been damaged wiring.
Usually a shorted starter doesn't intermittently work.
Usually a melted wire means a short.
Take your pick.
I think it's safe to say the damaged wire AND the starter need to be replaced.
Which I also clearly stated in my post.


My post is the way it is because I was correcting misinformation while avoiding quoting the multiple posts and writing a treatise on the subject.
Some of it could have been explained further but it was intended as a quick explanation for those that already have some understanding.

@jaxs Care to explain where I went wrong? If I actually did make a mistake I'd rather know so I can fix it.

 

[GreensvilleJay]

I'll add even more cornfusion..
re:
A bad connection or corroded wire adds resistance.

Not always true...

Consider that 1/2 the fat battery cable is bad( corroded,high resistance)), that requires that ALL the starting current(100s of amps ?) has to flow threw the good half. This can create a LOT of heat ( P=IIR law ) and either melt the insulation or burn up the 'good' half of the cable.
From an electrical view a stranded cable should be considered as lots of parallel wires.
It's one reason I always strongly suggest replacing ANY 'maybe bad' cable.

 

[Soopitup]

I'll add even more cornfusion..
re:
A bad connection or corroded wire adds resistance.

Not always true...

Consider that 1/2 the fat battery cable is bad( corroded,high resistance)), that requires that ALL the starting current(100s of amps ?) has to flow threw the good half. This can create a LOT of heat ( P=IIR law ) and either melt the insulation or burn up the 'good' half of the cable.
From an electrical view a stranded cable should be considered as lots of parallel wires.
It's one reason I always strongly suggest replacing ANY 'maybe bad' cable.

I'm sorry but you're wrong.
That IS always true.

Current flow (amps) is the same throughout the entire circuit.
If you add resistance anywhere in the circuit, you lower current flow in the entire circuit.
If part of your battery cable is corroded that lowers current flow through the entire starter motor circuit. Not just through part of the circuit.



You're thinking of available voltage. That will change.

Take a 12 volt circuit with a single load ( a light bulb).
Measure the voltage anywhere up to the bulb. It's 12V.
Measure the voltage anywhere after the bulb. It's 0V

Measure the current ANYWHERE in the circuit and it will be the same (let's say 6 amps).
Measure before the bulb. 6A.
Measure after the bulb. 6A.

Now add a second identical bulb. Now you have 2 loads.
Measure anywhere up to the first bulb and you'll have 12V.
Measure anywhere between the 2 bulbs and you'll have 6V.
Measure anywhere after the second bulb and you'll have 0V.

Now measure the current ANYWHERE in the circuit and you'll have 3 amps (double the resistance, halve the current).
Before the first bulb is 3A.
Between the first and second bulb is 3A.
After the second bulb is 3A.


The corrosion acts like the second bulb. You're adding a load.
The only difference is the voltage won't be evenly split.
The amount of voltage used by each load is proportional to it's resistance compared to the other resistances.
So if you had an 8 amp bulb and a 4 amp bulb the 8 amp bulb would use twice the voltage of the 4 amp bulb.

*A corroded/bad/loose connection is a load. A corroded wire is a load. You can fix the connections. You can't fix a corroded wire. "Cleaning" the outside doesn't do anything. It has to be replaced.

Twisted stranded wire is obviously made up of lots of small strands of wire twisted tightly together. Current flow depends on the individual strands having as much contact between themselves as possible. When the individual strands are corroded or untwisted they lose their connection. No way to get it back.

This is also why stranded wire isn't all the same. If you have 2 wires that are the same gauge but one has smaller (finer) individual strands than the other, the wire with the finer strands will conduct better and run cooler than the wire with the thicker strands. Even though they're rated at the same amperage (rating is usually based on the gauge of the wire, not the quality). It's also more flexible, especially at lower temps.
Thicker strands are also (very slightly) more prone to corrosion because there's more air gap between individual strands.
And finer wire is more expensive.

So when you're replacing your factory wire with cheap Autozone wire, there's a reason it's cheaper.*

 

[Soopitup]

For the record, the bulb (or any load) example is if they're in series ( in line with each other).
Parallel is different. But that's for another day.

------O-----O----- Bulbs in series

-----O-----
-----O----- Bulbs in parallel. The wires would be connected at the ends.

 

[GreensvilleJay]

OK , soupitup humor me

Take a 2' long section of #14 ( house wire) and 2' of #22 (bell wire )
Draw 15 amps through each of them, then try 100 amps
Please report back what happens.

 

[Soopitup]

OK , soupitup humor me

Take a 2' long section of #14 ( house wire) and 2' of #22 (bell wire )
Draw 15 amps through each of them, then try 100 amps
Please report back what happens.

I'm not sure what you're trying to say?

I don't think the 22g wire can handle 15 amps, and I know it sure won't be able to hand 100 amps.
The 14 gauge won't be able to handle 100 amps either.

Basic DC wiring here. Nothing fancy.

 

[jaxs]

Soopitup I agree with what you said the first time and never asked you to prove anything. Obviously there's two types , #1 that is here to talk about the science and #2 that is trolling to entice #1 into debate who can dazzle more readers and pizz highest on the wall. One can talk on and on about how atoms are arranged in motor oil or tires until everyone loses interest and go's on their way. I simply asked all parties to stipulate corroded ,loose and poor connections are at the heart of most electric problems and refrain form intentionally complicating simple solutions. Op has school hoped on down the road anyhow so it isn't worth any more of my time.

 

[GreensvilleJay]

AS individual strands become damaged(corroded, high resistance) the starting current has to try to go through what's left of the cable. The problem is you CAN'T push 100 amps through what is effectively a smaller gauge wire. Say the cable is made from 21 strands and then 7 are damaged, so now there's only 14 strands in that cable. The cable overheats due to the high current flowing through it. Gets even worse as motor is probably series wound and with less terminal volts, tries to draw MORE current to make the required power.

Same problem exists in cable stayed bridges, somewhat more dramatic though when several strands fail......