temp gauge not working

[Dave-T]

Changed out my radiator today in the ol 78 hilux (20R). Gauge worked fine before the swap, but since the new radiators' been in it isn't functioning at all. The temp. sending unit comes off the thermo housing, I never touched it at all. When I replaced the thermostat a month ago or so the gauge didn't work after I put the new thermo in. Shortly thereafter on a wim it fired up again and started to read. Hopefully that will happen again this time.

Any ideas why it wouldn't be functioning or any things to check?

Thanks, Dave

 

[hobiesbestfriend]

Mine works intermittently as well, although it's on an 85. It's a loose connection behind the gauge cluster. If I bang the top or bottom of the dash around the area it pops back on.

 

[Dave-T]

Well thankfully it started working again. My only guess is maybe it takes some time for air to leave the system and coolant to reach the temp sending unit.