I have a problem with the coolant temperature gauge on my 88 IROC-Z. When going to start the gauge drives full scale, like it should, except the needle drives so far it gets stuck on the bezel. Does anyone know if there is supposed to be an internal stop on the gauge?

If the ingnition switch is just placed in the run position the gauge works normal. It is only when the ignition switch is placed in start and the ground is supplied to test the gauge that the problem occurs.

Anyone have some suggestions?

Thanks,

Chuck

 

After checking the system again this past weekend I suspect that the gauge might have an internal spring that pulls the needle towards the cold side. If so I suspect that this spring has broke. Unrestrained the needle swings off the scale when the lamp test ground is applied during engine start.

Two questions I have that maybe someone could answer:

1. How high does the gauge go during engine start? (Quite frankly I never paid any attention to it during engine start. But I know it didn't fly off the scale and get stuck).

2. When the engine is shut-off does the indicator stay down around the cold side of the scale? Mine slowly floats back up toward mid scale or higher.

Thanks,

Chuck

 

The gauge sets to whatever temprature the engine is when power is applied (key in 'run' position) because it is now being 'controlled' by the sender. With no power to the gauge, it's free to drift to wherever it feels.
The gauge should, fairly quickly, go to full hot during crank. The gauge is grounded through the ignition switch during crank. This is a 'test sweep' to show the gauge has full range of motion w/o being in a bind.