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Discussion Starter · #1 ·
I thought I saw a diagram that showed the hot coolant coming out of the engine through the thermostat into the bottom of the radiator. That's where I installed the temp probe for my electric fan. Now it seems like the engine is almost overheating before the fan comes on and the top hose is much hotter than the lower hose. Did I screw up and install the probe in the wrong place? Does the coolant flow into the engine through the thermostat?:headbang::headbang:
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Yup...they showed you wrong. 
Coolant flow comes from the upper hose and into the radiator. After going through the fins, the coolant is cooled. At the bottom of the radiator, the ATF (if applicable) is cooled at the bottom through it's own circuit. The return coolant flow is controlled by the thermostat located at the inlet (bottom hose) to the engine. This allows the thermostat to keep the water in the radiator moving faster or slower depending on the coolant temp.
This inlet is also where the water pump is located. If you have a 4WD 5vz-fe, yer oil cooler circuit comes off of the water pump via a nipple.
Which kit did you git? You should be able to adjust the range at which the fan turns on/off. Yer probe should be located near the top of the radiator as this will be the hottest area of the radiator. You should still have yer shroud...if not...the performance of the fan will be limited/neutered.
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Discussion Starter · #3 ·
Thanks of the info. I used a Hayden fan controller and I installed the taurus fan inside the OEM shroud. For now I am just going to run the low speed since I am having trouble finding a two speed controller that will work with the Taurus fan. I think I need to figure out how ford controlled the fan and get those parts. I will post picks soon as the truck is almost ready to come out of the garage!
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Discussion Starter · #4 ·
If the cold coolant is flowing through the thermostat into the motor, wouldnt that cause the thermostat to close?
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If the cold coolant is flowing through the thermostat into the motor, wouldnt that cause the thermostat to close?
Yes. The purpose of the thermostat is to regulate the temperature of the engine coolant. Too hot...open up. Too cool...close down.
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Discussion Starter · #6 ·
Makes sense, although the purpose of the thermostat is to regulate the temperature of the engine, not the coolant. That's why I assumed the flow would be the other direction since when the engine reaches operating temperature, the thermostat opens to release the hot coolant and allow cooler coolant to enter the engine to cool it off.
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Well...I would expect the coolant to regulate the temp of the engine...the thermostat just controls the flow.
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Interesting. Just to make sure I have it right, the thermostat is at the bottom intake, at the engine. All the other thermostats I have changed out, on other vehicles, were at the top.
Also, I just changed out my radiator. It was leaking at the top where the plastic is attached to the metal fin section.
Thanks
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Interesting. Just to make sure I have it right, the thermostat is at the bottom intake, at the engine. All the other thermostats I have changed out, on other vehicles, were at the top.
Also, I just changed out my radiator. It was leaking at the top where the plastic is attached to the metal fin section.
Thanks
Yes...follow the bottom hose and it will take you to the thermostat and water pump inlet.
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coolant flow
I have a 96 T100 3.4L 2wd: 260K
I have been experiencing overheating:
I changed radiator due to leak 5 months ago, hoses as well...
I have been overheating again so figured I would change water pump(original)
Also changed the thermostat
I did this and timing belt and pulleys.
Im still overheating. Here are the symptoms of type of overheat:
Truck warms up to normal operating temp.
Heat Blows fine
about 10min of normal driving..Heat turns off truck temp rises.
Upper hose hot
Lower hose cool
Overheat is boiling the overflow bottle.
Even with a new thermostat from toyota, still doing this. (Jiggle valve at 12:00)
I tried a venturi vacuum and replaced fluid to make sure no air bubble issue.
Same thing remains... Thermostat position is with spring end into the engine correct ?? (just making sure after reading flow comes out of bottom hose and into thermostat, then water pump and comes out the top and back into radiator from top)....?? Any suggestions ? Block test next maybe ?
Thanks
Rob
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WHen you say heat turns off you mean you do not have heat anymore correct?
If your lower hose is cool (and your overheating) its either 1) your thermostat is not letting coolant flow past or 2) you've an air bubble or bubbles in the system blocking flow (somewhat) randomly
Your best best is to try bleeding the system again. Park on hill (nose up) so cap is as high as can be. Run heater while doing this. Run motor with cap off - squueeze rad hoses if you like, but EVENTUALLY you'll get your air pocket that is blocking your flow (past radiator and also to heater hoses).
I venture to guess that when "lose" heat that both heater hoses are cooler to the tough and both are roughly the same temp. Can you verify that?
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When I say heat turns off, I mean hot air turns to ambient temp air blowing...
I will verify heater hose temps...
Is there any chance there is a second thermostat at the top of engine, top hose from block to top of radiator ?
Also joggle valve I installed at 12 o'clock..I see some related emails says should be in the 6 o'clock position...
Rob
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Yes jiggle valve should be at 6 o clock - no there is not a 2nd thermostat. If it were me I'd pull thermostat, install jiggle at 6 and burp it. You'll see a difference.
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Correct 6 Oclock. No codes? Just checking since it's so easy to jump a tooth when changing belts, especially if you skip turning 720deg before rechecking & buttoning up- school of hard knocks talking.
Source: https://www.toyotanation.com/threads/coolant-flow-direction.358024/
Posted by: elnaelnabalme0272399.blogspot.com
