I have a '99 GMC 1500 Sierra (aka Silverado)........it has the 5300 engine with 27K miles on it. Lately it has been running a bit cool, around 180-85 degrees in warm summer wx. I suspect the thermostat but I can't find it. Where is it ????? I have heard that it may be a part of the water pump and that the whole unit may have to be replaced just to change the stat.....anyone know ????
dwk