CooLant Hose Cold???? Normal?????

Guys,

I just did a coolant flush in my 99 2.7L. But i notice my lower coolant hose is always cool to the touch when the upper is warm/hot after good amount of driving.

Is that normal with all you guys????? I have a working thermostat that i already tested in boiling water.

 

Pretty much in a cool climate. Where do you live?
For the lower hose to be warm, unless it was a very hot day, your cooling system would not be working. That is what a radiator does: radiate heat from the coolant. Goes in hot, comes out cold.

 

im in NorCal. where temp is 60-70 currently.

I always thought the bottom hose should be hot which was the coolant from the block to the radiator and the top hose is from radiator to block (which should be cooler)

am i wrong?

 

Yes. the thermostat opens on top of the motor and flows engine heated water to the radiator,,down thru the radiator to be cooled by the fan and airflow (or both),, now cooled water thru the lower hose back to the pump and then block. A regulated-by-temp repeat.

Your thermostat sits in the block with the temperature capsule sitting in block heated water. Once the water hits a certain temp,,that wax expands and pulls(or pushes) the thermostat open,,to allow radiator cooled water to flow into the motor from the whole radiator via the pump.

Several engine manufacturers have reverse cooling,,which is basically opposite of the above with everything in the same spot with the path reversed. They are usually a higher pressure system,,and can be finicky.

And you also just did a coolant flush,,,. Sounds like you have no air pockets and it filled like it should,,good job.

 

Not sure if you are familiar with the 3rz-fe 2.7L 4-Cylinder motor but my thermostat is located near the middle-lower of the block (driverside) connecting to the LOWER coolant hose.

With this setup, i would think it would be the hot water flowing out of the block through the thermostat into the bottom hose then into the radiator.

So shouldn't my bottom hose be hot? at least warm??

 

Yes your thermostat is where you say it is, but it is covered (inside of) part number 16324, which Toyota calls a coolant INLET, which means that when the thermostat opens, it let water INTO the block, not out. The upper hose is connected to a block OUTLET, which would be passing hot water to the radiator.

 

I'll keep this short to eliminate any confusion.

Your good!

If the top hose is cold, then you have worries. Comprende' Amigo?

 

That makes hell of alot more sense! Thank you. Much appreciated

 

There may be others, but this is the first engine I've seen where the thermostat allows water into the block, instead of out. Others on the forum may be aware of others, or even why they built it this way.
I guess as long as it works, the world is a good place to live.

 

that was the part that i got confused too. my bottom hose has always been cold to the touch after running engine for good amount of time. I guess i have a very efficient radiator.

Also, do you guys know if my cooling fan is suppose to be on at all times for this 3RZ-FE motor? Some has told me its a mechanical fan driven by connecting belts so its always on but not sure if thats true or not.

 

If it has a belt turning it, it is always turning, though there is a heat operated fan clutch that allows it to slip some until it get hot enough where it has to run full rpm.

 

Is there anyone else on here with same motor that can confirm this?

 

Try this, with the engine off and the keys in your pocket, grab the fan and spin it. If it spins freely, you have a fan clutch, if not, then the fan will turn when the engine is running all of the time.

 

Oh, Brother.

 

haha, sorry to give you guys a headache. But all this information is great. I am much appreciated of everyone who helped. I will go play with my fan tonight and see what i came up with.

I was just hoping there are others with the 2.7L motor can tell me if you are experience same thing or there is something wrong with part of my cooling system.

 

I have the same problem on my v6: a after driving 10 min, temp gauge is pegged, radiator is hot along with top hose, bottom hose is cool; coolant isn't flowing thru (even after installing new thermostat). I can squeeze bottom hose together and touch the inside walls. Mechanic says it needs to burp, but how do you do that too?