Alan208

I recently bought a 1990 pickup with the 3vze. It was running on 3 cylinders. I tried timing and nothing changed. I tore it down and found three injectors were plugged. I cleaned them and put new gaskets timing belt water pump radiator thermostat and belts. It runs fine but overheats. The bottom hose is cold while the top hose is hot. Doesn't seem to circulate the coolant! Does have a little vapor coming out the tail pipe. Could it be a blown head gasket? It's not dumping coolant out the exhaust just a little vapor that seems to dissipate as it warms up. It's in the 40s to 50s here. Any help would be much appreciated.

Thanks Alan

thefishguy77

iTrader: (1)

Run a compression test or a hydrocarbon test for head gasket. With the radiator cap off start the rig and let it warm up. When its up to temp do you see coolant moving in the top of the radiator? What does the oil look like? Do an oil change and see if it looks like a milk shake, blown head gasket, or just normal used oil. It could just be a bad water pump that had the fins eithe seize up or spin free and wont turn when the belt is turning the pulley. Hopefully this is the problem.

Alan208

I did a compression test they were all 130 or 140 the oil looks clean the coolant moves with the cap off but it doesn't seem to pressurize till it's overheating. I assume the flow on these goes from the bottom to the top? Most vehicles have the thermostat on the top hose.

Alan208

Up until it's almost overheating the top hose will be hot and pressurized while the bottom hose is cold and not pressurized.

thefishguy77

iTrader: (1)

Have you bypassed the heater core by joining the hoses with a fitting to see if there is a blockage in the heater core? Could you have a stuck closed T-stat? Easy to test by just pulling the T-stat and then starting it up.

Alan208

The truck didn't have a T-stat when I got it tore down so I put one in it. I loosend the housing with the upper radiator hose off when coolant came out I put my palm over the hose and could fill the suction and it stopped pouring coolant out. Would a blown head gasket on one cylinder cause it to not circulate and overheat?

thefishguy77

iTrader: (1)

Shouldn't cause it to stop flowing, I don't think...

Can you disconnect the heater core hoses at the firewall and then with low water pressure and see if you can push water through the cooling system?

I an actually trouble shooting a cooling system on non Toyota rig and just going do the same thought process I just went through.