'98 durango, 5.2L, w/ AC
it threw the serpentine belt while driving. i drove a few blocks to a safe place and discovered the belt was off and wrapped around the fan shaft.and of course it overheated as the waterpump wasn't working. i discovered the water pump pulley bearings were bad and was loose which caused the belt to come off. so i replaced the water pump (which was a treat in itself) and the thermostat. now, it will still overheat after a few blocks. the temp. gauge relines. with it in idle, everything runs great. no missing, temp.issue, nothing. when driving, during which it runs ok but may stall at stops,the temp pegs. when parked and turned off, you see pressured steam coming from the engine area but not the radiator, nor does anything overflow. just steam.
options?

 

Thermostat might be stuck in the closed position

 

sounds like you have air in the system... you'll need to bleed the system and get the air out. another thing you can try is to pour water on top of the t-stat when cold... that will help it open. I usually just drill a small air bleed hole in the diaphram to allow air to escape during the re-fill process. I've never had a problem when drilling a small hole...

 

Thanks. I did a couple of things at one sitting including fooling with the hoses to get rid of air, new radiator cap just in case, and removed and reset the thermostat. I'm betting that even though it was a new stat, it was stuck. I did however read somewhere that worked great was to test the stat by putting it in boiling water for a minute and remove it and you can see whetherthe spring action is working. Great tip. All is well now.

 

Alwaystest your thermostat before installation!