Over Heating: Upper Rad Hose Hot, lower cold (1 Viewer)

brooklyn

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Overheating with the FJ40 today. The Upper radiator hose hot and that side of the radiator is hot. The middle of radiator is warm and the side of the radiator with the lower hose is cold. Popped the cap and Hot Fluid came out "overflowing."

I am thinking water pump, but never experienced this before. I have a V8/aluminum radiator/electric fan. Fan is working fine, but with no flow across the radiator I am getting no cooling. No noise from the water pump, so I don't know if it has failed == do they make noise when they fail?

So what do you think?
 

Poser

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When was the last time that you changed the thermostat?
 

brooklyn

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Themostat Changed

Did that when I put the radiator in about 2 months ago. I am thinking the thermostat is opening as the hose off the thermostat is hot as is that side of the radiator.

It is the lower hose that is cold. Water isn't flowing through the radiator or so it seems. Which has me thinking water pump, but before I pull the pump was wondering if it could be something else.

I may just try taking the thermostat out and see if I get flow.
 
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I would think frozen radiator also, not only is coolant not circulating by something is slowing down the transfer of heat throughout the cooling system and the radiator especially.
 

inkpot

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Another possible cause could be if the lower radiator hose has collapsed. Many times custom setups use hoses that arent preformed, allowing them to kink. John
 

brooklyn

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Frozen Radiator & collapsed hose

Never heard of that. I guess, that would mean taking the radiator out and removing to a warm place . The FJ40 did sit for a month during the snow we had, so maybe that is a factor.

Will pull the thermostat in the morning and see if this is the cause. Next I will pull the hoses of the radiator and see if I can get a good flow from top to bottom.

If that all looks good, I might as well pull the water pump and see what that looks like.

Let's hope the thermostat is the issue.
 
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I assume you had a coolant and water mixture and not just straight water. If the radiator did freeze you might want to check for cracks after it unfreezes.

Maybe find a bottom hose that has the wire coil in it that is common for top hoses, if that is the problem. Keeps it from collapsing.
 

inkpot

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Howdy! I forgot to ask earlier, if the coolant still looked clear, like new, when it overflowed? If not, you may have blockage in the radiator due to contamination. Water pumps ALMOST always fail due to the bearing/seal going bad on the shaft behind the pulley. I have seen one where the impeller blades had corroded away, and I have seen one where the impeller came loose on the shaft. John
 

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