Water temp bad ground or sender?

[pjoll84]

Hey everyone,

I’m starting to go through this (new to me) dodge class c motorhome with a 318.
I drove it home about 20 miles and the temp gauge never reached past the bottom bar at 170…

*edited as my initial post was hardly legible lol* well today, I noticed after running it for a ten minutes… I took the key out to do some other work, put the key in and turned to ON and the gauge moved UP past the lowest mark… but when I started it, it dropped back down BELOW the 170 mark

 

[kiwigtx]

There could be a build-up of rusty crud surrounding the sender unit inside the waterway.....or the sender could be corroded around it's own thread.

There could also be bad wiring connections between the sender and the dashboard.

Many different places to look for a solution.

 

[pjoll84]

There could be a build-up of rusty crud surrounding the sender unit inside the waterway.....or the sender could be corroded around it's own thread.

There could also be bad wiring connections between the sender and the dashboard.

Many different places to look for a solution.

Cheers, thanks for the suggestions. Initially I thought maybe the tstat was stuck open or no tstat at all but I took the rad cap off and started it up… no movement of water on start up (which I would assume confirms the tstat is closed)

Since this thing is 50 years old and I don’t know when anything’s replaced, I’ll check the electrical connections and replace (tstat) and the water temp sender… barring the electrical checks and clean codes the issue

 

[kiwigtx]

Initially I thought maybe the tstat was stuck open or no tstat at all but I took the rad cap off and started it up… no movement of water on start up (which I would assume confirms the tstat is closed)

If you're getting movement on the gauge, then the thermostst is moving - may not be enough, but at least it is moving.

There is still the likelihood of the thermostat being all crudded up as well. I suggest a water flush when you can....then at least you know the water can move about the place.
Take off the bottom hose also and watch the muck flow out. Reverse the flow of the hose when flushing so that you can loosen any light debris. Just use water this first time, later on you can use a chemical to release any more crud if necessary.

 

[WileERobby]

While you're doing the sender and t-stat, replace the bypass hose.

 

[Chargerjase]

I had issues with mine. It turned out to be an intermittent connection at the bulkhead connector. As others have said, pull it and check for crud build up on the threads of the sender. Test the wiring back to the gauge. If you ground out the signal wire, the gauge should go to H. You can do that as a quick check.