i have a 94 4.0 and i just recently changed my thermostat to a 190 from a 180, when i had the 180 the temp would stay below the N on the "NORMAL" gauge and when going up a hill get to about the "R" but never past the "M". Now that i have the 190 it goes up and down from the "N" all the way to the "A" is that normal? the temp goes up when i stop and it goes up and down when i drive... im just asking becuase im used to all my vehicles staying at a certain temp and if it goes up from there then thats when i know something is wrong

 

Not sure if it is supposed to do it or not. My 93 3.0 did the same thing sitting at a light it would creep up then as soon as I move it would go back down.

If it worries you Turn the Heat on full blast and it brings the temp down

 

My 1990 belches every now and then when driven hot i turn the heater on full blast and it works. The best soultion is to put an electric fan on it. That will help keep your fluids cool and not reling on just one fan

 

I wonder if maybe it has an air bubble stuck in the cooling system? Maybe take off the radiator cap, start it up and let it idle for a while until the coolant gets warm and purge out the air.

 

x2

 

I've purged it a couple times... I have a new radiator and waterpump but I looked closer and when the previous owner changed them he didn't change the hoses... So I'll change the hoses and flush the coolant and see what happens

 

your engine is going to get hottest when you idle and coldest at crusinig speed. personally i would have kept the 180 thermostat if you are running a stock engine, however the 190 is fine. your engine will flucuate tempreature anywhere from 170 to 210 degrees depending on what you are doing.

 

You should compare the temps with another gauge or infrared temp gun, to see what it acutally is.