tach reads 3000rpm at idle

[_Cheese_]

I just bought a 92 lx 5.0 hatch 5spd. And the tach reads 3000rpm at idle. It will read past 3000 when the engine atchually revs past 3000rpm. But any lesser rpm from idle to 2999rpm the guage will show 3000rpm.
It will read correctly after 2+ hours of driving but then when the car sits over night the tach goes back to reading 3000rpm.

Any ideas??

 

[jrichker]

The electronics on the tach are no longer functional. The simplest thing to do is to replace the tach. Keep in mind that the 4 cylinder tach is a different animal from the 8 cylinder tach.

 

[Wildstringer]

+1 sounds like the needle is stuck and possibly the heat from under the dash has something to do with it working after driving a while. If you are going with an after market tach they are set up for an 8 cylinder. If its used and they guy had it in a 4 cylinder(????) you would have to reconnect a wire.

 

[_Cheese_]

for replacing the tach, would i need to replace the whole guage cluster or does the tach unbolt sepertaly from the cluster?

 

[stangman11]

As far as I know its the entire cluster I have never actually taken apart the cluster piece by piece

 

[jrichker]

The tach comes out of the cluster once you remove the clear plastic cover. It is a press fit on 3 studs that are the tach signal, ground and switched 12 volt power.