Temperature Sender Questions

[CRM]

What is the difference between these 2 different senders?

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Autozone lists one as being for a gauge (right one) and one for a light (left one). My temp gauge doesn't work and the sender installed in the engine is the type listed for a light. Does it need to be the other type? Is there another sender on the engine I'm missing that sends a signal to the gauge? My truck is a '77 C10 Custom Deluxe with a 250 c.i. engine. My daughter and I are just starting to restore this truck and we want to fix the important things first before we make it look pretty. Any help would be appreciated, and we will be posting a lot of questions during the restoration.

 

[CRM]

After spending the day working on different parts of the truck I got around to looking at the temp gauge issue. I remember reading on another thread that the gauge could be checked by shorting the green wire to ground, which pegged out the gauge. That's the first time in 10 years I've seen it move. I purchased a new sensor , installed it, and the gauge works great. It runs on the high side, just shy of the hot line. I can tell when the thermostat opens too. I also managed to rebuild the washer pump and it's working for the first time too.

 

[Georgeb]

Goad you got it figured out!

 

[SkinnyG]

If you have the gauge sender connected to a light, the light gets brighter and brighter as the engine heats up.

 

[CRM]

Now that my gauge is working I noticed it runs at the 3/4 mark on the gauge. It will get up into the hot area until the thermostat opens and then drop back to 3/4. I read on another thread here that all sensors don't have the same resistance reading so I got my volt-ohm meter and put the temperature probe down the well of the broken ported vacuum switch at the top of the thermostat housing. It measured exactly 195* which is what the rating of the thermostat is. I'm going to purchase a AC Delco G1852 coolant temperature sensor,which after a lot of study, appears to be the closest replacement for my 77 Chevy.

 

[CRM]

Installed the AC Delco sensor this morning and took the truck out for a drive. The gauge now goes up to 3/4 and drops to 1/2 after the stat opened. I can live with that.