Order the 180 degree AC Delco thermostat, not the $14.95 professional, this one

http://www.jcwhitney.com/p3042205/sku-3503285.jcwx

 

Hey fast, read through some forums and you will find that your temperature is within the normal range, and all the situations you described are 100% normal. No need to worry. Analog doesn't move much. In fact, if you are bored enough and watch it, it doesn't even rise gradually it "jumps" from spot to spot. Your digital readout is fine

 

Changing the timing chain fixed your overheating! It was slightly higher than it should have been. 190F is a good average while moving in 80F ambient.

 

Well, now I noticed that the coolant temperature was going up slower than usual after starting it. I was suspecting a stuck open thermostat, and then a few days later I got he usual --- digital readout, no analog gauge reading, and eventually P0128. So maybe my original problem with erratic higher temperatures was a failing thermostat.

Looks like I will be replacing the thermostat soon. This is a new AC Delco from Rock Auto that I installed in January. It was probably the "AC Delco professional" model rather than the one that oldblue recommends (AC Delco 131158 OEM model).

So what is so special about the OEM 180 degree thermostat over the professional 180 degree thermostat? So now even AC Delco makes a cheaper "crappy" part also? I still can't believe a thermostat costs so much ($31 !!! at Rock Auto).

Steve

 

The difference is the construction, the materials and it opens to the ECMs satisfaction.

 

That, plus it does not have the inner rubber gasket to fail. It is a metal to metal seal when closed.

 

Yes very important, Donbrew. It's that rubber ring that causes the most problems.

 

Update: I have had no problems since I cleaned the terminal on the coolant temp sender. I guess there must have been some corrosion causing intermittent readings.

 

Thank you for the update

 

OK, I doubt that I am looking at bad T-stat number 4. (DIC flat line.) I'm thinking this has to be a bad coolant temp sensor. Is it ACDelco 213-4514?