I got a 92 V6 4runner and I had a small leak with my radiator so I decided to replace it with a better looking used one. I put the used one in a started it and it overheated on me. So I thought maybe it was clogged or something where the thermostat was so I took out the thermostat and ran water through the top hose. At that time I decided to replace the thermostat and gasket since they looked a little old. I then filled everything with antifreeze and tried it again....it still overheated. So then I thought maybe the replacement radiator was no good so I decided to swap back in my old one and now it overheats! I have no idea why it overheats now and it never has before. The hot air doesnt work on the vents anymore either.

Any ideas? Oh and my top hose gets hot but my bottom one doesnt

 

Check the thermostat in a pan of water on the stove to see if it opens. If it does, then put it back together and make sure that you bleed all of the air out of the coolant system. Air pockets will cause this to happen.

 

lower hoses or water pump?

 

Is it overheating when just idling or when driving? Did you purge the cooling system after replacing the radiator and thermostat? Does it overheat then come back down to normal operating temp?

 

Got it working now! There was air in the system but it works now. Thanks for the replies!

 

Awesome! Glad you figured it out.

 

Yeah all I did was park it on a hill facing up then kept squeezing the lower hose and refilling the radiator