Gauges sticking when cold

My oil pressure and fuel gauges on my 89 do the same thing every now and then.

 

Do you really want to go through the trouble of taking the gauges out of the dash binnacle, disassembling them to clean/lubricate them (hopefully without damaging them in the process), reassembling them (again, hopefully without damaging them in the process), and reassembling the whole thing just because every now and then you have to tap the gauges to wake them up? I personally wouldn't go that route. My oil pressure gauge does the same thing. I kind of look forward to giving it a tap on startup if pressure does not show right away. These kind of things help me to connect with my car, get to know its quirks, and feel involved with it. Embrace it.

 

That’s a sign of not being driven enough

 

Mine does that, but not just when it's cold.
Glad to know it's not just me

 

There is the antique film from the 1960s when many drivers do the tap tap

 

My fuel gauge needs a tap once in awhile, I think of it as 'percussive maintenance'.

 

My fuel gauge on my 328 always needs a tap.

 

Nope, mine have always done it. Conversely, when headlights are switched on all the guages jump forward a bit

 

I love when they give the fuel gauge a tap in the F-14 in the movie Top Gun.

 

The gauges stick because over time the small stop inside the instrument that the needle rests against gets just a little sticky. It is worse when the gauge is cold and it causes the indicator needle to 'just' stick enough where the load on the needle from the gauge is not strong enough to pull it away from the stop. A tap on the glass of the instrument is enough of a shock to break this bond free as the contact area is incredibly small. This is why it only happens on the gauges that park themselves all the way to the end of the scale against a physical stop.

The way to fix this is to totally disassemble the instrument and clean the stop with a little rubbing alcohol. If you want your gauges to operate perfectly this is the correct way to do things but it is a LOT of work to do and for most just not worth the effort when a little tap is all you need. I hope this explains things for everyone. Been there done that.