Sender Question

[88trailblazer]

I recently swapped out my engine harness and gauges on my '78 with a set from an '84. Now my temp and oil pressure won't work. Did they change over the years? I grounded the wires and the gauges move fine. So i know the wires are right and the gauges aren't stuck.

Also, my temp sender is mounted to the top of the water neck. Is that okay? I can't tell you if its inacurate because i havent had working gauges in the last 2 or 3 years owning the truck.

 

[dyeager535]

Gauge specs are the same all years. Only (potential) differences are in how they are wired at the cluster connector, and if they are senders or switches, since idiot lights use switches.

Coolant temp is most accurate at the cylinder head, BUT, since the water neck is an outlet, and the block is pressurized, it's not like cooler fluid is going to reverse out of the radiator into the thermostat housing when the engine is running. I would expect that the gauge operation would be more "jerky" mounted by the thermostat depending on how your t-stat operates. If it opens quickly then the gauge might swing quickly.

In any case, I suppose if somehow the t-stat sticks closed, you could have a serious issue as you'd not see what the block temperature REALLY is, at least not as quickly as you would see if it were in the cylinder head. That's the only time I could see a problem with it in the fill neck. Otherwise, once the t-stat opens, it's going to show engine temp, and no matter how high the engine temp goes, as long as the t-stat is open, the gauge will read accurately.