Engine Cooling problem
1992 Mazda b2200 4 cyl Two Wheel Drive Manual 175000 miles
I have a 92 b2600. The truck would run cold and then jump to way hot. I have bypassed the heater core, removed thermostat, new pump and cap. I have bubbles and overflow out the reservoir. Could trapped air cause this or should I jump to head gasket? I don't have white exhaust or water on dipstick. Haven't had fluid sniffed.