1997 Blazer - Radiator replaced 3 years ago, water pump 2 years ago and since beginning of 2010 I've had intermittant overheat issues. Had 2 thermostats put in in past 9 months, as it hit 260 a couple times with just a short drive. It's always run really cool, so it freaked me out. Figured everything was fine with 2nd new thermostat. Then, took a trip from GA to KY last month and it hit the red, check gauges, service engine soon light... three times. I turned car off, back on and the gauge would kick down. Made it there and back, but had to do the same drill on the return trip. Stopped at Auto Zone when I got home and the guy said it could be a bad radiator cap. $4.00? I was thrilled. In town driving is a breeze,... runs real cool. Last week I had to drive 30 miles and back and it hit the red again. What in the world is going on??? I've taken it in to the shop and they couldn't make it overheat. They think I'm crazy!!! I will give them a little credit. They said they didn't want to "throw darts" at the problem... they don't know what to fix. Well... I am planning on driving 8 hours to FL next month and need to figure this out before I go. I love my Blazer and don't want to kill it. Please help.

 

do a drain and flush, try to clear out anything that could floating around in your system. Is it ever steaming and the Overflow tank is bubbling from overflow from the Rad, when its hits the red?