Toyota 4X4 with overheating problems

BADFISH_KK

MEMBER
TOYOTA PICKUP

I own a 1992 Toyota 4x4 pickup with a 3.0 v6. It has a problem with a recently rebuilt motor that has around 25,000 mi. On the new motor. It started having the same problem that it had before the rebuild. The problem is that it overheats whenever it's driven over 65 mph. + Or - 10mph depending on wind direction, air temp. And AC use. I think it's blowing coolant out the overflow bottle. I've replaced the radiator, Flan clutch [twice], and can't find any leaks in the hoses or heater core. It doesn't seem to use any coolant when driven under 55mph. What else should I do and check. Thank You. Kit

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Could be a bad new thermostat installed or an air lock problem. Try bleeding it and if it doesn't work try the other suggestion.

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.

Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat, Pressure test the Rad. Cap, Clogged radiator, Fan clutch, Radiator electrical fan, collaspe hoses, water pump.