MTD Lawn Tractor Starting problem

[Richie F]

OK thanks for that info.

 

[bertsmobile1]

Your reasoning is a possibility.
I have seen moisture migrate in a wire before.
But if it did wouldn't you see the positive cable from the battery bad also ?
The positive cable goes straight to one lug on the solenoid where the fuse wire gets it's current from.
How did the corrosion migrate ?

Corrosion is a GALVANIC reaction between 2 different metals in the presence of an electrolyte, usually water
The reason why you see a lot at the battery - and very little at the battery + is because the flow of electricity at the - strengthens the reaction & at the + it reverses the reaction
When this was noticed it begot a whole field of engineering called CATHODIC PROTECTION where things exposed to the elements were perminantly energised to drive the galvanic cells backwards .
IT is the reason why a lot of motor vehicles went from - ground to + ground in the 40's to prevent all of the ground connections from corroding .
It was not particularly successful so in the 70's most vehicles reverted to - ground.

All corrosion is galvanic in nature be it macro , 2 or more different metals in contact or micro differences in the electro potential within the actual metal grains themselves.
Any 2 metals and in many cases a metal & a conductive non metal can make a battery remember the potato batteries you should have made in high school chemistry / physics ?
For simplicity we give specific classes of redox reactions specific names.
If we pull the surplus electrons out of the reaction vessel we call it a battery
If it happens to metal stuff we have made we call it corrosion
They are all the same thing.

 

[The Maintenance Guy]

Sorry to see as a "The Maintenance Guy" you didn't (from what I'm reading) first off didn't have a wiring diagram.
From there you could have followed the current path from battery to all components.
You did the "what if" repair.
Like too many people just keep spending money on parts not needed.
Glad you finally found your problem.
But the question is ? How did that fuse holder melt ?

Just plain old corrosion, nothing melted. The connection was intermittent, and in addition the starter was bad. Makes it tough when a couple things wear out at once.