today was the first real craptastic wintery day we have had this year and my 4runner over heated on me. i popped the hood and saw the collant boiling out the reservoir. i checked the top hose which was hot and the bottom hose that was cold- water pump failure?

 

I would check the thermostat first, it's in the lower hose, assuming you have the 3.0. Quicker, cheaper and easier than the water pump.

 

wouldnt the upper rad hose be cold if the thermostat was stuck closed?

 

Not really sure, but I would think if some coolant boils out of the rad then you'd get flow through the upper hose to replace it.

 

Could be a headgasket. Check your oil for coolant, and coolant for oil.

 

i think the headgasket would have led to doggy preformance wouldnt it have? regardless- there wasnt anything out of the norm in the coolant when i drained it and the oil was rather low so i didnt see anything in the shape of moisture in there (nothing on the oil cap either). i have the thermostat out but am not quite sure on whether that is the guilty party here- how can you tell if its not functioning properly? the spring seems fine, it seats right and the seal looks ok. oa''wgq'ihd'klsdfah(<----- beating head on keyboard)

 

just threw the old thermostat and new one in a boiling pot, and the old one opened up wide just before the new one started to open up. I'm assuming that means the old one is good?

 

If the old one opened fully in boiling water it's probably OK, they should open around 85 deg C. Could be the water pump after all, I'm not really an expert on overheating issues.

 

bump- i dont want to start replacing things that dont need to be replaced especially with chri$tmas coming up. anyone else chime in?

 

and to think i thought this might be easy for someone. i just bought an airline adaptor to plug into the cylinders and pressuring to see if i have any air leakage into the collant- good idea bad idea or what?

 

Good idea, that'll tell you if you have any headgasket leaks. Let us know what you find.

 

i blew a head gasket once and didn't know it until i saw coolant dripping off my mud flaps.