This old Runner that I recently purchased is keeping me busy.....I spent hours upon hours reading here and yesterday was readinmg about burping the coling system and also looking for small bubbles in rad coolant indicating head gasket trouble. Well today I opened the rad and ran the truck for about 30 mins at idle and reving here and there, within 20 minutes the coolant was steaming hot. I found thid to be pretty quick soo I shut it down, recapped and then felt the rad, top half was super hot and lower half was almost cold to the touch, not as should be, right? The rad is fairly new 8 months I think th PO said, so I doubt it's blocked passages, what else could be the cause?

Derek

 

doesnt matter how old the radiator is...if there is something in your coolant system it can find its way anywhere in the radiator and clog it. I would remove it and test the radiator

 

I changed out the thermostat today and ran pressured water through the rad everything with the rad seemed alright. I reused my coolant and it was very clean, no sediment gathered at the bottom of the container that I emptied into.
What is a regular operating temp. according to the temp. gauge? Mine runs with the needle just to the left of the little thermometer picture on the gauge, and it gets to this temp. quite quickly, usually within 10 minutes of idle. Is that considered normal for a toyota? 3.0, v6, 270,000 mi.