Okay, so I have a 94 4runner 3.0, 4x4, auto. I just replaced the Radiator because the old one had a slow leak. Never had it over heat with the leaky radiator though, tried to be proactive and replace it. I just got a replacement Murry from the parts store ( have a feeling this is the problem). Went together fine no issues. Tried to drive it to work the following morning, got out of the driveway and noticed the temp gauge almost in the red. So, I parked it and took a different car to work. So I thought it might be the thermostat. I removed it and put it in some boiling water with a thermometer to see if it opens when it is supposed to, it did about 80-85 degree Celsius. Then I remember seeing a little boiling coolant by the radiator cap when the truck over heated. So, I though maybe the old cap doesn't seal to well on the new radiator. Bought a new cap and put it on, still over heating. I noticed the upper hose and upper tank were hot but the bottom hose and tank were not hot. Any ideas? you guys think the new radiator is a piece of poo?

 

Now dice huh? Okay do any of you know if there is any other type of controller or valve that controls the coolant flow, besides thermostat, that would cause overheating? I dont have my service manual yet and ive been looking online but don't see any mention of anything else. I am going to get a new OEM thermotat today, hopefully that will fix the problem, even though i think the old one is fine. I really hope its no the pump.

 

Sounds like you have an air bubble in the cooling system. Does the heat in the truck work?

 

Heater worked before but didn't checked that when it overheated. I know when i filled the radiator back up i let it run for a couple minutes without the cap on, try to get all the air out. But dont remember seeing any air bubles come out. Is there a better way to get air out? Because this is how I always did it with my other vehicles. So, if the heater doesn't get hot, does that mean i no coolant circulation?

 

X2 on air bubble,
Jack the front up or find a steep hill and turn on heater and run, but keep an eye on temp gauge because it could be something else, good luck and post back what happens.

 

Holly, it was air the whole time. This time around I filled the top Rad hose, the end attached to the engine, till full then attached it to the radiator. This took a whole gal by itself. Then I fill the radiator as normal, warmed it up and took it for a spin, and all seems good. I was about a gallon short the first 2 times. Thanks for all the help.

 

Okay, so around town the 4runner does fine with temp. Today I decided to go up to Big Bear (SoCal mountain if you are not familiar) to snowboard. One the way up the 4runner did fine temp stayed just below half. When returning home, mostly downhill, on the little uphill sections the temps started to go a little past half. These were short uphill sections so I just turned on the heater and really didn't sweat it too much, because once I started going downhill again the temp went back to normal. Are you guys with 2nd gen, 3.0, 4x4, auto experiencing the same thing? Is it just because its an older vehicle?

 

you still have air in the cooling system make sure t-stat opens when you burp it that way the last big burp of air comes out

 

Are you sure your fan clutch is working?

 

You need to let the truck get to operating temperature with the cap off and the heater on hot to get all the air out of the cooling system.

 

I did warm up to operating temp and left the cap off with heater on. I'll do it again to see if i can get more air out. Clutch fan im not sure, it does spin, but how do i know if it engages when its supposed to?

 

Pull your rad cap, and start the truck, turn your blower to his, and your heat to on. Let it run for quite some time, and once at operating temp, carefully (they will be hot) squeeze and bend any rubber coolant hoses you can reach.

Sometimes the little extra movement can help purge a stubborn bubble.

 

Squeeze, squeeze spill coolant all over the place, and that will fix it it right up.
You might as well face it you have a problem, and it ain't those magic reappearing air bubbles.

 

This with the heat on at full blast.

:wabbit2:

 

Okay did everything to try to get air bubbles out, but I don't think there is anymore. I did check the fan. When engine cool the fan turns by had but there is resistance, kind of like spinning in oil, does not spin freely like a pinwheel. When at normal operating temp, with engine off it feels like there is more resistance. When engine is first started, cold, it is easy to stop the fan with an empty toilet paper roll. When engine is on at normal operating temp, I cannot stop the fan with the same toilet paper roll. So, from what I have read this is normal and seems to be working properly. Anybody think that it is the cheap radiator I bought from the parts store? The Radiator that was on there before was all metal with 3 core design. replacement is an aluminum core with plastic tanks, and 1 row. I have read some posts about efficiency and that more rows doesn't mean better cooling. It just seems like the new single row is not doing a good job when I am trying to go uphill.

 

Lighten up Francis...

Unless the truck is going into the red or boiling over when you're pulling these hills, you're making something out of nothing. The engine is going to heat up slightly under a heavy load. There's a few hills around my place where you can feel the heat in my truck get better by the time I let up at the top. Couldn't tell ya how much the gauge actually moves since mine doesn't work, and I don't plan on fixing it cause the temp gauge is like an oil pressure gauge, you don't look at em till there's a problem.