Tach Works but Whines!

[jtmaynard]

My tach started making a whining noise when the engine is running, which increases in pitch along with the RPMs. Other than that, the gauge works. I assume it's a broken cable, and if so, I'm dreading the fix! Or does the tach itself need replacement?

[Benz Dr.]

The main part of a tach or speedo has a shaft with a magnetic flywheel on the end inside of the gauge. The grease on this shaft will dry out or harden over time and your tach or speedo will complain LOUDLY This is a problem in colder climates but the noise usually goes away once it warms up inside your car.

Gauge needs lubrication and cleaning in most cases.

[Pagodatastic]

I had the identical problem.
The tach meter would wine loudly when the car was cold.  As the car heated up the noise would stop. The dial needle moved as normal.
I disconnected and removed the meter and sent it away for total refurb.  The grease inside had dried up. Popped it back in / reconnected and worked ever since. 

[kampala]

I sent my screaming tach and speedo to  Overseas Speedometer in Austin Texas : speedometer.com

You also have a major speedometer/ VDO instrument rebuilder in Palo Alto close to you.