Temp affected tachometer

[JAKRANCH]

I thought my tach only worked sporadically but as I watch closer it begins working once the coolant temp gets up to 115 degrees. No idea how the sensor works could someone enlighten me?

 

[chillman88]

Is your wiring factory or has it been tampered with?

Odd that it would start working about the time your cold advance and high idle shut off...

 

[Thewespaul]

Check the connection on the timing gear, your pickup for the tach is on ththe driver side. It is common for those wires to become frayed or loose there, could be that heat is affecting that.

 

[Hydro-idi]

It’s probably the tachometer sensor that’s on top of the IP gear tower. Mine did the same thing years ago. Wouldn’t be accurate when cold but would be good once engine warmed up.
A new sensor fixed that.

 

[chris142]

Mine has done this for decades. Its in the dash as I can hit it and get it to work when it's cold out.

 

[JAKRANCH]

Thanks everyone!