electrical and ignition Temp sending unit? Gauage? Ground?

[jshap02]

So my water temp sender unit had some oxidation and corrosion to it, I figured that was why it wasn't reading temp- so I hit it with a wire brush and alas, when i turned the key it flickered!

 

but would not rise to middle blue/red on the white...even at operating temperature..the ground seems good, the sender lead is making contact..do i replace the sender? how do i check the gauge? any theories? also does anyone have an opinion on a 71 degree thermostat - i figured that would be best for an older vehicle to avoid overheating?

 

 

[bento]

I just switched from a 71 degree to an 80 degree thermostat. My 71 degree thermostat failed and stuck open. The needle would barely get out of the blue and my heater barely heated anything. Before it failed, it stayed well below center of the range. How much heat does your heater put out? You should be able to roast yourself out of the car with a fully functional 02 heater.

With the 80 degree thermostat, the temp gauge is right at dead center of range all the time, though I just replaced it and any warmer temps are months away up here.

Not saying that's your problem, but just offering a non-electrical possibility to look at.

For what it's worth, my mechanic (an 02 specialist) recommended a 75 degree for a little extra margin of safety in traffic. I had already bought the 80 degree thermostat, so I threw it in and we'll see what happens this summer.

Others here have probably tried them all and can comment on pros/cons of the different options.

[FunkyLaneO]

A rudimentary test of the gauge and wiring is to just touch the sender lead to grounded metal and the gauge should max out, if it does then the issue is most likely the sender.

[Mike87]

Check the ground with a VOM from the sender body to the engine. There could be corrosion between the sender and the crush ring and the crush ring and the water neck. If you don't get 0.2 ohms or less, remove the sender and clean the contact surfaces.

 

Also, what bento says above is also relevant.

[M3M3]

Cooler tstat does not keep old engines cooler. Cooling systems in good condition do that. Leave the tstat at stock temp.

[tashakes]

Engine ground? My temp gauge was bouncing like crazy and engine misfiring (albeit a M42) before I found I was missing a solid engine ground.