Radiator Flow?

[Diagram14]

Im thinking my thermostat is toast. How noticable is your flow when your cap is off? My lower hose doesnt warm up, but my temperature gauge seems to be as solid as ever. Which is confusing to me. I would think that my water temp would go through the roof if the tstat was stuck closed.

Long shot, but do you think that the pressure built by uncirculating coolant could have caused my head gasket to start leaking?

Thanks.

 

[brian2sun]

What started your worry, because you can't see the flow in the radiator through the hole for the cap, or do you have other issues? I can't really see the flow on mine either. Our temp guages move slowly from C on up and then they stay put right below 1/2 way regardless of when the t-stat opens/closes.

You would overheat if your t-stat was stuck closed. It's just that our guages aren't sensitive enough to pick up the difference when the t-stat does it's thing. Unless you're loosing coolant or overheating, it sounds like you're looking for a problem that's not there.

Your lower hose doesn't get very hot because the cooled coolant is sucked by the water pump from the bottom of the radiator on a 3.4, that's why the t-stat is on the bottom hose instead of the top. The hot coolant leaves the engine and goes back to the radiator through the top hose.

 

[Diagram14]

My concern stems from my troubleshooting of and resolution options for the coolant leak I have on the back side of my block. I am 99% sure its my head gasket. One of the options (I know you'd rather break my arm, Brian, than see me do this) is a Stop Leak treatment. On several occasions now I have pulled the cap and warmed the motor up to check the coolant flow, however, I have yet to see any. I realize that, just like every other cooling system, the hot coolant is pumped into the top of the radiator and cycled back into the motor cooled by the bottom hose. My concern is that I do not feel much, if any, temp change in the bottom hose from start up to just below middle where my temp gauge sits all day long at operating temp.

Preemptive defense against Brian: I got myself into a 4runner that has turned out to have been completely abused and neglected, I resolve one issue and another one springs up as I latch the hood on the previous. So I am trying to get enough "bubble gum" in this thing to kill the dripping so I can trade it in on one in better shape and an e-locker. If I felt this one was worth my time and money for a head gasket job I wouldn't consider the liquid fix.

 

[Gerdo]

My lower radiator hose is pretty much room temperature. Even when wheeling in the 115* summers of Moab.

 

[brian2sun]

Haha, as you'd expect, I don't like stop leaks but if you're gonna go that route they make stop leaks specifically for HGs. I've only used it once on a HG and it sealed the leak for a few months, but it clogged the water pump and made it leak bad immediately and it gummed up the heater core and pretty much the whole cooling system. This was years ago on an old S-10. I would properly diagnose it's a HG before doing that.

Can you see it leaking out between the head and the block? There are 2 big coolant hoses on the back of the block right by the firewall, have you checked those?

 

[Diagram14]

I have done my best to check any coolant hoses on the back side of the motor. My leak is on the drivers side so I think it could only be the hose that is high center. I believe the second was on the passenger side. I cleaned the area around the drip/collection spot really well to see if I could see any runners but it just seems to be spawning from the very spot where it drips. I wish it were just a sliced hose...

 

[calinaki]

flow path

Question for you all: for the 3vZE: I always thought that the thermostat opened and then allowed flow through it in the direction of the radiator. However, I heard that the flow from the engine is into the top of the radiator and then the cooler fluid is out the bottom of the radiator to the thermostat. So my question is, how does the thermostat "sense" the hot temperature if it's in contact with the 'cooled' flow off the bottom of the radiator? The jiggle valve would also allow a small amount of flow from the bottom of the radiator, through the tstat to the opposite side of the tstat. Am I thinking about this correctly??? THanks for any clarity! I can't find a flow path anywhere for this cooling system.