Coolant Flow Direction? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

HawaiianMike · 07-02-2018, 03:27 PM

Does anyone know for certain which direction does the coolant flow in our cars? Does the coolant come out of the top port of the radiator, or go into the top port of the radiator.

Ill check the temperature differences between the two to see which leaves the engine (but I'm at work and am thinking of pointless projects).

Thanks!

Icecreamtruk · 07-02-2018, 04:28 PM

Since the thermostat is in the lower hose side, I would imagine coolant goes into the rad there and out the top, no? Just guessing tho.

humfrz · 07-02-2018, 09:18 PM

Well, for years now, the coolant went into the top of the radiator and came out the bottom of the radiator on most gasoline engines .. why would this one be any different?

humfrz

Ultramaroon · 07-02-2018, 11:21 PM

Quote:

Originally Posted by humfrz

why would this one be any different?

I can't think of a good reason. Maybe they were doing it wrong all that time.

humfrz · 07-02-2018, 11:59 PM

Quote:

Originally Posted by Ultramaroon

I can't think of a good reason. Maybe they were doing it wrong all that time.

Yep, it all started back-in-my-grandfathers day. When the Ford model T came out, it had a water pump .. then, they eliminated them because they kept leaking .. then some modders put them back on .. then Ford put them back on because cars were overheating in 4th of July parades.

NOW, that we have this "boxer" type engine, that sits flat, but it is still water cooled, whereas the older flat fours were air cooled. So, since a water pump is needed (or is it?), should the water be pushed (or pulled) from one side to another or from front to rear or rear to front? Further more, if we had a radiator on each side, could we just allow natural convection to move the water through the water jackets .. thus eliminating the water pump altogether which would get rid of the water pump pulley and not requiring the mod for a lightweight pulley.

humfrz

Ultramaroon · 07-03-2018, 01:03 AM

Quote:

Originally Posted by humfrz

could we just allow natural convection to move the water through the water jackets .. thus eliminating the water pump altogether which would get rid of the water pump pulley and not requiring the mod for a lightweight pulley.

Before water-cooled two-stroke motocross engines were water-cooled head kits. They had no pump. Hot water in the top of the radiator and cold out the bottom.

They didn't work very well.

humfrz · 07-03-2018, 01:21 AM

Quote:

Originally Posted by Ultramaroon

Before water-cooled two-stroke motocross engines were water-cooled head kits. They had no pump. Hot water in the top of the radiator and cold out the bottom.

They didn't work very well.

Maybe they needed a bigger radiator …

We had a 1941 Ford 2 ton truck back on the farm. You could fill it with hay or grain and run it in granny gear all day long on the hottest days and it would never overheat. Why not? Because it had a radiator that was about three feet wide and about four feet tall ….

humfrz

Muskoka800 · 10-01-2022, 12:03 PM

So, did we determine coolant flow direction?.
I recall some muscle car engines boasted “reverse flow” back in the day.
I’m wanting to install an inline sensor for water temp so must confirm which hose carry’s the blocks coolant output.

Ultramaroon · 10-01-2022, 05:44 PM

Coolant always flows from the hot side of the thermostat through the valve plate.

^^^I'm leaving this here even though I was wrong.

Actually useful diagram

Grady · 10-01-2022, 05:59 PM

Why would you try to suck from the top were you can have air?

makinen · 10-02-2022, 06:41 AM

Quote:

Originally Posted by Muskoka800

So, did we determine coolant flow direction?

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JD001 · 10-02-2022, 07:42 AM

i'm wondering if the flow differs if the car lives in northern or southern hemispheres?

Muskoka800 · 10-02-2022, 11:02 AM

Thank You All!
I’ll be installing the sensor block into the lower (larger diameter) rad hose.

soundman98 · 10-02-2022, 11:17 AM

Quote:

Originally Posted by JD001

i'm wondering if the flow differs if the car lives in northern or southern hemispheres?

Better run and check all your neighbors toilets!

That was a good Simpsons episode

07-02-2018, 03:27 PM	#1
HawaiianMike Member Join Date: Aug 2016 Drives: 2015 Brz Limited Location: New York Posts: 34 Thanks: 7 Thanked 4 Times in 4 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Coolant Flow Direction? Does anyone know for certain which direction does the coolant flow in our cars? Does the coolant come out of the top port of the radiator, or go into the top port of the radiator. Ill check the temperature differences between the two to see which leaves the engine (but I'm at work and am thinking of pointless projects). Thanks!

10-01-2022, 12:03 PM	#8
Muskoka800 Senior Member Join Date: Jul 2018 Drives: 2016 Scion FRS Release Series 2#439 Location: Chatham, Ontario, Canada Posts: 680 Thanks: 3 Thanked 150 Times in 123 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	Coolant flow output hose? So, did we determine coolant flow direction?. I recall some muscle car engines boasted “reverse flow” back in the day. I’m wanting to install an inline sensor for water temp so must confirm which hose carry’s the blocks coolant output. __________________ Edelbrock S/C with CSG 94 & 91 maps TRD Short Shifter, CTS/EvoX Brakes Ohlin’s R&T Dampers, Hotchkis F/R Bars, Blox LCA & Toe Arms 235F/245R Conti ECS on TRD/Enkei wheels (street), 245/40 sq. A052 on 17x8 720Form GTF2 wheels (track)

10-01-2022, 05:44 PM	#9
Ultramaroon 義理チョコ Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 31,867 Thanks: 52,128 Thanked 36,519 Times in 18,920 Posts Mentioned: 1106 Post(s) Tagged: 9 Thread(s)	Coolant always flows from the hot side of the thermostat through the valve plate. ^^^I'm leaving this here even though I was wrong. Actually useful diagram __________________ service manuals Last edited by Ultramaroon; 10-02-2022 at 03:08 PM. Reason: Owning my shit

10-02-2022, 11:02 AM	#13
Muskoka800 Senior Member Join Date: Jul 2018 Drives: 2016 Scion FRS Release Series 2#439 Location: Chatham, Ontario, Canada Posts: 680 Thanks: 3 Thanked 150 Times in 123 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	Thank You All! I’ll be installing the sensor block into the lower (larger diameter) rad hose. __________________ Edelbrock S/C with CSG 94 & 91 maps TRD Short Shifter, CTS/EvoX Brakes Ohlin’s R&T Dampers, Hotchkis F/R Bars, Blox LCA & Toe Arms 235F/245R Conti ECS on TRD/Enkei wheels (street), 245/40 sq. A052 on 17x8 720Form GTF2 wheels (track)

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07-02-2018, 04:28 PM	#2
Icecreamtruk Senior Member Join Date: Dec 2015 Drives: Track preped NA FRS Location: Montreal, Canada Posts: 987 Thanks: 1,056 Thanked 680 Times in 405 Posts Mentioned: 12 Post(s) Tagged: 0 Thread(s)	Since the thermostat is in the lower hose side, I would imagine coolant goes into the rad there and out the top, no? Just guessing tho.

07-02-2018, 09:18 PM	#3
humfrz Senior Member Join Date: May 2013 Drives: 2013 FR-S, white, MT Location: Puyallup, WA Posts: 29,868 Thanks: 28,790 Thanked 31,816 Times in 16,425 Posts Mentioned: 708 Post(s) Tagged: 2 Thread(s)	Well, for years now, the coolant went into the top of the radiator and came out the bottom of the radiator on most gasoline engines .. why would this one be any different? humfrz

10-02-2022, 07:42 AM	#12
JD001 Senior Member Join Date: Apr 2015 Drives: Subaru BRZ Location: UK Posts: 6,028 Thanks: 7,652 Thanked 6,187 Times in 3,474 Posts Mentioned: 25 Post(s) Tagged: 2 Thread(s)	i'm wondering if the flow differs if the car lives in northern or southern hemispheres?

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