Engine temp indicator drops to nothing sometimes

[BigMike]

The engine temp meter needle, that should point at 9 o'clock when warmed up drops down to nothing sometimes.

What does this indicate? 

I read somewhere about someone changing the thermostat to correct this.  Is this the only fault condition that causes this?

Thanks,

Mike

[sgould]

When does it drop?

The classic symptom of a failed thermostat, if it sticks open, is that the engine is slow to warm up.  The needle goes to normal in traffic, but drops back to low when you get on the open road and airflow through the radiator increases.

If the needle drops randomly, it's likely to be a temp sensor, or the connections to it.

[BigMike]

When it drops it drops quickly - ie immediately, so probably not a thermostat issue.

I'll pay more attention and see if I can see a pattern.

Thank you,

Mike