problem keeping motor warm

[Quinn]

car is: '92 240sx KA24DE auto

okay, so i live in northern wisconsin. cold, right? yes. so it takes a little bit for the motor to warm up. the needle will go to about the middle of the temp gauge and stay there. but if i drive over three hours in one day, the needle drops. usually about to the first dash, sometimes right at the C. if i turn it off for a few minutes then turn it back on, the needle will rise back up a couple dashes. but then it'll drop back down within a minute. it doesn't seem to matter what type of driving i'm doing, wether its city or highway. i can open up the hood and touch the motor when this happens. like put my hand on the block and leave it there. its warm, but not hot. i can even touch the exhaust manifold cover, warm but not hot. like grabbing a fresh cup of coffee. warm, but not hot. theres coolant in the overflow tank, and if i loosen the radiator cap a bit water will come out. again, the water is warm but not hot. i can't tell if theres an air bubble in the lines or something but if i squeeze the hoses i can hear the water squish through them. i don't think this is normal and can't think of any good reasons this would happen. any help would be great, thanks.

[cheviot]

It may be the thermostat is staying open. I had the same problem with a U11 and a U12 Nissan Bluebirds that I owned and both times it was the thermostat stuck. The car would only warm up while it was sitting but driving along it would cool down again.

[Quinn]

ok thanks i'll Check for that.