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Discussion Starter · #1 ·
Can someone verify which way the coolant flows. I assume it flows from the thermostat(bottom hose) to the bottom of the radiator. The spring on the thermostat is in the engine, therefore in contact with coolant at different temperatures, it opens, sending coolant to the radiator. :undecided
 

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:laugh: yes I believe it enters through the lower hose and cycles through and comes back out through the top hose


but I may be wrong... god knows something else GM decided to overthink something stupid :bonk:
 

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It would have to come out of the engine at the t-stat. If the water went into the t-stat from the radiator it would not be hot enough to open the t-stat.
 

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It would have to come out of the engine at the t-stat. If the water went into the t-stat from the radiator it would not be hot enough to open the t-stat.
Remember this is GM eng. doing this......... Who knows what they are thinking....... Maybe it is cold fluid that makes it work.......
 

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Discussion Starter · #7 ·
It runs backwards as compared to other GM vehicles. Typically the T-stat is on top, with the spring inside the block, so it runs into the rad via the top hose. But this runs into the rad via the bottom hose. Just wanted to make sure I was not over thinking it. :weird:
 

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:crackup: I forgot about the GM Engineer Factor.
 

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Fire it up and see which hose is hotter.

I'm gonna do this tomorrow - on my other vehicles the hot coolant entered at the top.
 

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Per my Haynes manual, the coolant leaves the engine block thru the T-stat. (which on traditional gm small blocks is front and center at the top)
 

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Per my Haynes manual, the coolant leaves the engine block thru the T-stat. (which on traditional gm small blocks is front and center at the top)
First we all know that Haynes manuals are NEVER wrong! (High sarcasm).

Second, since the thermostat is at the end of the LOWER radiator hose, the coolant flows into the BOTTOM of the radiator? That doesn't make sense.
 

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The last time I looked ( I need to add, looking from the front) the coolant flows from the bottom of the left side tank of the radiator through the lower hose to the water pump. The water pump pumps the coolant through the block and heads and the heater hoses. The coolant absorbs the heat from the engine that heats the thermostat that is mounted in a housing near the top of the engine. There is a cover over the thermostat that holds the thermostat to the housing (or manifold) that the upper radiator hose is connected to. The heat sensing "pellet" is under the thermostat and when the engine heats the coolant to the operating temperature the pellet expands, pushes the thermostat open, releasing hot coolant to the upper hose and right side tank top to the radiator . The coolant flows across and down in the radiator and air flowing through the fins on the radiator removes the heat. The cooled coolant then flows back into the engine.
 

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The last time I looked ( I need to add, looking from the front) the coolant flows from the bottom of the left side tank of the radiator through the lower hose to the water pump. The water pump pumps the coolant through the block and heads and the heater hoses. The coolant absorbs the heat from the engine that heats the thermostat that is mounted in a housing near the top of the engine. There is a cover over the thermostat that holds the thermostat to the housing (or manifold) that the upper radiator hose is connected to. The heat sensing "pellet" is under the thermostat and when the engine heats the coolant to the operating temperature the pellet expands, pushes the thermostat open, releasing hot coolant to the upper hose and right side tank top to the radiator . The coolant flows across and down in the radiator and air flowing through the fins on the radiator removes the heat. The cooled coolant then flows back into the engine.

You haven't changed the thermostat in an I6 engine recently have you?

I just did - the thermostat connects to the LOWER radiator hose which is on the drivers side of the engine. It may look like the short upper hose is where the thermostat is at - but trust me it is not. It would make replacing the thermostat a MUCH easier job if it were on the upper hose. Thank you GM engineers!
 

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First we all know that Haynes manuals are NEVER wrong! (High sarcasm).

While they are quite lacking in detail, I have always found what they do put in there is quite accurate.
Second, since the thermostat is at the end of the LOWER radiator hose, the coolant flows into the BOTTOM of the radiator? That doesn't make sense.
Maybe not to you. I would argue that pushing the fluid up from the bottom to the top results in a more efficient cooling system. Since the fluid is going against gravity, it will stay in the radiator longer, resulting in more time to get cooled. I wish I could reverse the flow in my Cutlass, so that it runs cooler, resulting in less cylinder hotspots, and less detonation at 10.50:1, when the ambient temp is above 80.
 

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Ok, all of this reading made by brain bleed,


All i know is that when i changed my t-stat and my hoses, and when i did all my tests for the e-fans, i had to flush and fill my rad quite a few times, what i can tell you is that the top hose, the one on the passenger side is the radiator in from the engine, the hot coolant flows from the engine TO the rad from the top hose and that the bottom hose of the radiator is the colder coolant out to the engine block, i've also verified this with a flash light at the coolant through the opening of the top rad cap,
 

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While they are quite lacking in detail, I have always found what they do put in there is quite accurate.
I'm glad you think so. That has NOT been my experience. I have seen numerous cases over the last 30 years or so where they were DEAD wrong. I believe they also said that the thermostat is connected to the UPPER radiator hose in the Trailblazer I6.

As to the flow, it only doesn't make sense in that it usually doesn't work that way. If it's more "efficient" or not is anyone's guess.

FWIW, I have one Haynes manual where the word "the" is spelled "teh" several times. While that not does not necessarily mean that rest of their info is bad - it still makes a person wonder!
 

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Discussion Starter · #18 ·
Pjaneiro, are you positive, are you will to stake a bet of you driving down here and installing e-fans for me?
Of course I am not putting anything up on the bet. :laugh:

P.S. How did the lift install go?
 

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This is from the 2003 Service manual: The t-stat opens to allow heated coolant to flow to the radiator.
 

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All i know is that when i changed my t-stat and my hoses, and when i did all my tests for the e-fans, i had to flush and fill my rad quite a few times, what i can tell you is that the top hose, the one on the passenger side is the radiator in from the engine, the hot coolant flows from the engine TO the rad from the top hose and that the bottom hose of the radiator is the colder coolant out to the engine block, i've also verified this with a flash light at the coolant through the opening of the top rad cap,
:iagree: that makes more sense (to me at least)

Here is what the much revered Haynes manual states:


"Coolant is drawn from the radiator by an impeller type water pump mounted at the front of the block. The coolant is then circulated through the engine block where it passes around the individual cylinders. After exiting the cylinder block, the coolant then enters the cylinder head where it quenches the combustion chamber area. The coolant flows out of the cylinder head and into the thermostat where, depending on coolant temperature, it is either blocked until the desired temperature is obtained or allowed to pass through the thermostat into the radiator."

Unless I'm reading it wrong, they are saying the thermostat is in the head.
 
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