Hey hows it going? Glad to finally find a website that I can relate to. Anyways new member but have a very confusing question(well confusing to me) but I have a 2000 chevy silverado 1500,4x2,flowmaster(Series 50) exhaust and a k&n cone filter. Well my question is that recently the temperature gauge goes all the way to red and it sounds easy but a couple of months ago it was doing the same but I replaced the thermostat (to my friends advice) but not its doing it again, but only some days, others its fine like normal.Please Help One last thing it also heats up when standing still but in drive its fine. Please help struggling student as it is...........................................

 

This may sound obvious to some, but sometimes its the obvious that bites us in the ***.... whens the last time you check your coolant level? It could very well be low and could cause the symptoms of which you speak. Also when's the last time the radiator and coolant system was flushed and cleaned with a good cleanser? Old nasty coolant would make everything else in the system work a bit harder and wouldn't cool as well.

 

If it heats up while standing, but cools while moving, that would seem to indicate that air is not being pulled through the radiator by the fan. Have you checked the fan clutch for slippage. You should be able to tell by looking at it while idling whether it's turning fast enough to pull air. Have you checked the front of the radiator for blockage that would keep the air from flowing through it?

Another possibility is that thecoolant is not moving through the radiator while at idle speed. That could be due to a faulty pump or some obstruction in the system.