No Heat, new thermostat

[pete123]

I just bought a used '98 4Runner. It has no heat. I've replaced the thermostat. It's not overheating. No leaking of coolant. What's up? Could it be a clogged Heater core?

 

[koulee]

Or they bypassed it completely. Heater core is a PITA to repair when it goes.

 

[JSwain]

When you replaced the thermostat did you let the engine run with the rad cap off, front jacked in air a bit and the heater on full blast? You need to do this until the truck gets to temp, then the coolant will flow through everything and any air pockets will burp out of the open radiator cap. Once the truck gets to operating temp and the thermostat opens you can top it off in the rad, close it, top it off in the reservoir and you should be good. Forgive me if this is how you have done it but figured it was worth a shot with what little info you have given.

 

[robb1887]

Might want to check the lines into the firewall to make sure they are connected, and the heater bypass valve (middle of the firewall with cable attached to it) is opening and closing