Donor motor over heating

C

colorado4runnin

New member
So a few weeks back, my motor in the runner bit the dust I lost compression in cylinder #6. Burnt valve. But my compression on the rest of the cylinder was all over the board.
So I found a 3.4 with less miles on it for $500 on cl.
Truck still ran so we got to hear it run. Bought it slapped it in my runner last weekend. All was good! Then it started to over heat. No problem, maybe just some air. So we burped it and burped it several times. No I change. so I changed the thermostat. It helped but not enough. Got a new fan clutch. Installed it Thursday. And drove it like I stole it. No problem it actually stayed a little cooler. Friday coming home from work. (30 or so miles) it started to over heat again. Fired it up yesterday drove it around no problem. Today I went a few places and got on the highway it started to over heat.
It looks like a new water pump. the timing belt is brand new so I'm guessing those were done not long ago. I have a new cap to try tomorrow. What else could be going on? Did I not hook something up right? It's not leaking coolant, it's been burped, New thermostat, New fan clutch, it definitely sounds like it's getting coolant back to the rad. Looks like new water pump. No smoking or coolant in the oil. And it's not taking or putting any coolant in the over flow. Any ideas? I'm way stumped on this. 99 limited 3.4L
 
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Update...

So it hits 210+. It would run fine if I had I had the heat full blast. A few nights ago I hit the auto carwash and let it run while it got washed. I turned the heat to cool. And finished up at the car wash. Went to get back on my way home so I turned the heat back on. Nothing. Just cool air. Talked to my Toyota guru. He said he believes there's still air in the system. So I went and bought a flush and fill kit from the parts store. Installed, back flushed the whole system. Refilled. Bleed the system with the front end up. Burped it for a hour. Shut it off. Let it cool. Bled the system again. Filled some up in the back tee fitting. Idled fine With no over heating. Let it bleed some more. No more bubbles. Took it for a spin on the highway. Fine with the heat on. Turned the heat to cool again, began to over heat again. Turned the heat back on. No heat again just cool air. It hit 215+ again. Turned it off let it sit. Now I have heat again. Until I turn it to cool. Then it repeats.
So could there still be air in the system? Or is there something else I'm missing?
 
Any cold spots in the radiator? Did you flow test it (whatever that looks like)? Just looking for things to eliminate. It's a little suspicious you burned a cylinder in the old motor that's one of the furthest from the radiator. Was that a sudden thing, or were you having problems with it?
 
heat said:
Any cold spots in the radiator? Did you flow test it (whatever that looks like)? Just looking for things to eliminate. It's a little suspicious you burned a cylinder in the old motor that's one of the furthest from the radiator. Was that a sudden thing, or were you having problems with it?
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No cold spots, I've back flushed the system, so no blockage. No that was a separate issue for that motor. But that one never over heated
 
Just a thought - could the thermostat have been installed backwards or with the jiggle pin in the down position?
Buckaroo
 
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