I've looked for this issue, but didn't find a reasonable answer.

It was really wet here today in the UP of MI, first day above freezing in 74 days!

After driving around in a lot of surface water, my coolant temp within the dash (not oil temp/factory gauge) began to drop to the bottom of its position, climb to operating temp, drop, climb... and it did this for ~15 mins, both at idle and moving. It DIDN'T go over normal operating temp, but it did indeed hit the initial starting point of the needle (cold) Mind you, I was driving the car lol. First day on dry pavement, I had to!

Does this sound more like an electrical problem as in a short? or does it sound like I need to replace the thermostat?

I apologize for my ignorance

Thanks fellas.

 

If your stat was closed it would cause it to overheat not go to the low side. I don't think it has anything to do with the stat. Most of the time they don't fail in the open flow position.

It sounds like your sending unit could be bad or maybe just a lose connection.

It's not ignorance you just don't know big difference. At least you aren't afraid to ask and learn.

 

Thank you for noticing that. I appreciate it! Honestly.

That's what I had read, about it failing "open." I'm searching for a picture of the sending unit.

Anyway I could diagnose that?

Thank you for the response!

 

To the contrary, I think your thermos is stuck open. When you idle it goes to warm and then drive and it goes to cold--- classic thermos. They dont always stick closed. Good Luck.

 

Thanks for the input. This morning the needle dropped only on the highway and picked up while driving through town.

Pretty sure it's the thermostat. Get a new one in and I'll update.

Thanks again, guys.