B7800 ignition switch problems.

[Hodgy]

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A couple of months ago my B7800 ignition switch was acting up. It would turn on, activate the glow plugs but not trigger the solenoid on the starter. Sometimes you could get the starter to work by wiggling the key. The tractor would start by crossing the positive terminal to the solenoid terminal. So I thought the switch was bad as indicated in a few posts here. I bought a new ignition switch and installed it. It worked for about a week and then stopped just like the old one. All the fuses are good, and I changed them anyway.

The last two times I used the tractor I started it by jumping positive to the solenoid. After I blew snow for about a hour the starter would crank with the key. That worked so long as the tractor was warm. This morning I tried again to crank it and no dice when it is cold.

Any thoughts from the experienced on the forum.


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[Hodgy]

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Never mind I fixed it with a flash of brilliance or stupidity. After posting I started thinking as to what was the difference between cold and warm. The answer was the switch had warmed up in the cab. I thought there might be some manufacturing oil or other substance on the contacts.

I took the switch off, sprayed alcohol in it and blew it out a couple of times with compressed air. Re-installed the switch and Bob's your Uncle, it cranked over and started, many, many times.

If you read this post in trying to help, just ignore me !

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[boz1989]

I was going to guess that you have an issue with a safety switch.

Sent from my LGMP260 using Tapatalk

 

[Henro]

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Never mind I fixed it ...and Bob's your Uncle, it cranked over and started, many, many times.

If you read this post in trying to help, just ignore me !

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Does Bob live in Canada too?

I thought he was in England...perhaps he came along with Harry and Megan?

 

[Hodgy]

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One good thing about me getting old is I can say I was wrong a lot easier.


I was wrong, cleaning the switch did not fix the problem. boz1989 was right, safety switch. First I checked the switch on the HST pedal, not that one. Then I had a look at the switch on the clutch. It looked like a flat steel tab that pushes in the piston on the switch was bent. It is to light gauge for my liking, will fix it properly when it warms up. I straightened it out and now the starter cranks.

I think the rubber boot that goes over the piston has hardened over the years and when it is cold provided more resistance than the steel tab could overcome so the piston was not pushed into the switch enough. Once I had used the tractor for a while the engine heat warmed up the rubber and the switch operated as intended. That is why the key worked when the tractor was warm.


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[GeoHorn]

WD40 or LPS-1 will lubricate that switch and likely fix the problem for a year or so.