overheating

[quote:44cc70902b="agomez618"]I have a 1998 GMC Jimmy 4.3 liter with 151,000 miles 4w/d. I replaced the thermostat and clutch fan, the weep hole on the water pump doesn't have any sign of coolant. I can drive it in town and my temp. gauge stays normal, then I travel on the highway and it starts to climb. If could help me out I would appreciate it. My oil doesn't look anything like a milky liquid, and no white smoke is coming out of my exhaust. :mrgreen:[/quote:44cc70902b]

Try burping the cooling system

Always bleed air from cooling system after replacing coolant. Set heater for maximum heat. Remove radiator cap. Loosen drain plug and remove drain bolt (if equipped) from engine block. Drain coolant reservoir. Fill coolant reservoir to MAX mark with 50/50 water-coolant mixture. Loosen bleed bolt and fill radiator up to base of filler neck. Close bleed bolt when coolant flows out without bubbles. Tighten bleed bolt. With radiator cap removed, start and operate engine to normal operating temperature. Add coolant if necessary and check for leaks.