Recently began having coolant temp issues with the 3.5 engine. Temp gauge would be at center/normal position then shoot up to Hot for a few minutes then drag down to normal again. I replaced the thermostat, upper and lower rad hoses and the temperature sensor. All parts were not the cheap versions either. Replaced any Dex-cool that I drained off to do the work. Everything was fine for a few days but then the gauge hot issue came back and today the gauge never got past the 1/4 mark and the check engine light came on. I read the codes and the were 0128 which was temperature sensor problem. Huh? I just replaced it with a new one. I'm thinking it's a wiring short or maybe air in the system which requires bleeding. Any thoughts?

 

The book says for my engine it has go be vac filled, but I used a no spill funnel to fill it and let it warm up and cool off with the funnel and then over the next few days filled if it needed it and everything was good. How is your heat.

 

Asked my wife about it because the hot issue always seems to happen when she's driving. She said when the gauge went to hot, the interior heat cooled down considerable but came back when the gauge went to normal. You may be onto something with the vacuum fill and/or air pocket issue. I filled the rad with a funnel and did the heat up-cool down thing and checked the levels. Everything seemed fine. I'm inclined to think it's an air pocket issue. BTW where do you find a manual for Uplanders? Can't find any aftermarket books on them.

 

I would check your fluid level make that the first thing you do in the morning. My books came with the van, it's the actual service manual from the dealer.