Ignition switch vs. Selinoid

mcg1238

Member
Hey!


I have been reading a lot about ignitions causing problems once they overheat. My confusion lies in the verbage.

external link lists the switch as the key tumbler. Does that really overheat? Yet there is a starter selinoid for sale also which to me (I know very little about electrical) would be more likely to overheat.

I did a search and tried to find posts related to this with pictures but was unable to. I don't have this problem but a lot of my terminals are rusty and I want to know what is going on in the future should it go bad.


Thanks!!
 
It would really help to know what tractor you're talking about.
Ignition switches and solenoids, or the lack thereof, vary by brand and model.
 
Red Blue or Green tractor
New or old tractor
A solenoid or key switch all work on the same basic principal.

A solenoid is used for cranking a motor over.
It can over heat but only in the cranking mode.
Once the tractor starts the solenoid is taken out of the picture.

A key switch consist of a key tumbler and the switch itself.
The switch part consist of point ends.
When you turn the key you are moving a little metal piece that connects the center of the switch to a outside point.
These point ends can get dirty; wet; corroded; loose.
All of these could lead to bad connections.
With bad connections you get heat buildup.
So the switch overheats and or looses connection from arcing.
 
The solenoid carries the large current draw to run the starter, which is only while cranking.
The key switch carries the current for the ignition all the while the engine is running.
They can be a weak link in the system. Especially aftermarket replacements.
Failure is often a no start condition or a sudden shut down while running.
The indicator is no voltage to the coil when the key is on.
A jumper wire across the switch leads will supply voltage and the engine will run.
Jumper has to be removed to shut it down.

BTW, welcome to the forums!
 
1. ? I don't have this problem but a lot of my terminals are rusty?. That is one known problem you do have. Internal condition of parts is only guessing. Rusty connections cause resistance and resistance causes heat. I suggest cleaning up the rusty connections and replace old brittle, cracked, bare wires. Severe rust or corrosion is a legitimate reason to replace some parts.

Pay close attention to both battery cables, both ends. All 4 connections should be clean and snug. Most overlooked one is where ground cable connects to tractor frame. If it connects to thin metal or braces, move it to the solid frame of the tractor as near to the starter as you can get it. If there is any question as to condition of battery cables do replace them.

2. Don?t worry about parts until you have reason to know they are bad and need replaced. Those old parts may actually be better quality than the replacements you can get today.

3. ?I want to know what is going on in the future should it go bad.? Internet searches are your friend. Study and learn how the circuits work and develop an understanding of troubleshooting procedures.

4. The most important tool you can have to work on old tractors (or anything else) is not found in your tool box. The most important tool you can have is in your mind....that is...and understanding of how it is designed to work.

You can do it, but be patient as it takes time and comes together a piece at a time like a jig saw puzzle
 
the key switch overheats.. because.. it's meant to carry the 2-4 amps of current that the ignition coil needs.. lets saw it's a
25w constant capable switch.

The problem is that many people decide it's a great place to tap power off of for (2) 35w head lamps.

Then suddenly, its running about 16amps.. instead of 4.

that's why there are problems.
 
The solenoid is a "relay",google relay to understand why relays are used and how they work. Clean all those connections and coat with di-electric grease.
 
"Red Blue or Green tractor
New or old tractor
A solenoid or key switch all work on the same basic principal."

To some extent I'd agree with you John, but when you compare
my 2N with a two wire key switch and no solenoid to my 335 with
a 7 wire key switch and bypass solenoid, it's not quite that simple.
A little more information is required for an accurate answer.
 

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