Bypass; Heater Control Valve

GilTheArtist

New Member
Dec 25, 2013
34
0
0
California
The other day i was replacing my coolant hoses and noticed that the bottom heater control valve hose had never been touched.
After removing the 2 hoses i saw how deteriorated the outlets were.
I did some reading and decided to bypass the valve instead of trying to replace it.

From what i read, the valve adjusts the amount of hot coolant running through the heater core.
There shouldnt be any hot air though until the blower is turned on, which would be a concern in the summer.
As i continued to read i began to realize that by expanding the travel range of the coolant by letting it always run through the heater core, it can actually keep the coolant slightly cooler. Then turning on the blower enhances this effect.

So i couldnt really find any reasons it would be harmful to bypass the valve.

I bought a 3/4" PEC brass elbow (which actually measures 5/8") but it was too small.
So then i bought a 1" PEC brass elbow (which actually measures 3/4") and it fit very snug.
I used a basic vacuum cap on the line that went to the control valve diaphragm after removing the valve.
As usual i cant upload pics but friend me on FB to see all the photos.
 

plaaya69

87T Supra
Nov 18, 2006
947
7
18
Lake County, IL
Out of the 10 years of owning a Supra, one of the two times it left me stranded was when the heater valve broke. That brittle plastic blew that whole upper heater hose section off in 2010. I been lucky on a used heater valve since then but this year for my build I bought a brass 3/4" 90 degree SharkBite fitting and with about 1k miles on it its been all good. I sanded down the two inner ribs on both ends so it has a smooth sealing surface for the hose clamp like the OEM one.
 

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Abe's 1987

Member
Sep 5, 2017
253
10
18
Houston,TX
Out of the 10 years of owning a Supra, one of the two times it left me stranded was when the heater valve broke. That brittle plastic blew that whole upper heater hose section off in 2010. I been lucky on a used heater valve since then but this year for my build I bought a brass 3/4" 90 degree SharkBite fitting and with about 1k miles on it its been all good. I sanded down the two inner ribs on both ends so it has a smooth sealing surface for the hose clamp like the OEM one.

Where do you have the hose on the driver side hooked up to? Even though houston is like 100°f even in the winter it doesn't hurt to have the heater working. And as mine is missing everything but the heater core I will use you design for mine, if it isn't copyrighted(Lol jk ;)).
 

plaaya69

87T Supra
Nov 18, 2006
947
7
18
Lake County, IL
Where do you have the hose on the driver side hooked up to? Even though houston is like 100°f even in the winter it doesn't hurt to have the heater working. And as mine is missing everything but the heater core I will use you design for mine, if it isn't copyrighted(Lol jk ;)).

I wish you would have caught me earlier as I just copyrighted it right after that post ;) . I need to get all these pictures I have of my build in a build thread but I just have to find the right picture hosting service that is forum friendly.

The driver side is the heater core return side and it connects to the L shaped pipe that runs along the engine that connects to the rear of the lower timing cover. It is best to always have the coolant flowing through the heater core since the 6th cylinder is the farthest from the radiator and runs the hottest.
 

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Abe's 1987

Member
Sep 5, 2017
253
10
18
Houston,TX
I wish you would have caught me earlier as I just copyrighted it right after that post ;) . I need to get all these pictures I have of my build in a build thread but I just have to find the right picture hosting service that is forum friendly.

The driver side is the heater core return side and it connects to the L shaped pipe that runs along the engine that connects to the rear of the lower timing cover. It is best to always have the coolant flowing through the heater core since the 6th cylinder is the farthest from the radiator and runs the hottest.

Lol dang to late I guess I'll have to engineer a new way. Maybe chisel a new hole for the return line into the radiator. Lmao

I'll have to check on that L shaped pipe and see what the po did to it, if it is even still on the car.

Yeah you should get your build up here. I love seeing pics of what others do as far as progress and mods. Sometimes the pics helps other figure things out by visually seeing.
 

plaaya69

87T Supra
Nov 18, 2006
947
7
18
Lake County, IL
Lol dang to late I guess I'll have to engineer a new way. Maybe chisel a new hole for the return line into the radiator. Lmao

I'll have to check on that L shaped pipe and see what the po did to it, if it is even still on the car.

Yeah you should get your build up here. I love seeing pics of what others do as far as progress and mods. Sometimes the pics helps other figure things out by visually seeing.

What I would do if I was not running a heater core is to face the top heater hose towards the driver side, use that 90 degree brass fitting in my earlier post and cut to fit a long 90 degree rubber hose ( like this one https://www.google.com/search?q=hea...UICygC&biw=1600&bih=768#imgrc=q3okLkahMzn7zM: ) to connect to that L pipe so you still have the coolant flowing. There is another factory bypass that uses a small rubber 90 degree hose on the passenger side rear of the cylinder head that connects to the upper section of that L pipe too but its still helps have coolant flowing though the other path.
 

Abe's 1987

Member
Sep 5, 2017
253
10
18
Houston,TX
Plaaya where did ya get that carbon fiber lower window trim piece? It looks nice!

Also love the cam gears!
 
Last edited:

GilTheArtist

New Member
Dec 25, 2013
34
0
0
California
The strange thing is that the silicon hose fit just fine on the back of the engine between the valve covers, but the other end required a 3/4".....
 

plaaya69

87T Supra
Nov 18, 2006
947
7
18
Lake County, IL
Plaaya where did ya get that carbon fiber lower window trim piece? It looks nice!

Also love the cam gears!

Thanks. I bought that crowl trim piece as a set and it came with carbon fiber door skill plates (which I have yet to install) about 8 years ago on ebay. They don't really list these kind of products anymore that much but your best bet is this place. They are the cheapest and offer tons of cool products. I personally like the carbon fiber body moldings and going for that in the near future.

http://retrospec-toyota-supramk3.blogspot.mx/
 

Abe's 1987

Member
Sep 5, 2017
253
10
18
Houston,TX
Thanks. I bought that crowl trim piece as a set and it came with carbon fiber door skill plates (which I have yet to install) about 8 years ago on ebay. They don't really list these kind of products anymore that much but your best bet is this place. They are the cheapest and offer tons of cool products. I personally like the carbon fiber body moldings and going for that in the near future.

http://retrospec-toyota-supramk3.blogspot.mx/

Nice they have a ton of nice carbon fiber parts.
 

Piratetip

Far From Maddening Crowds
Staff member
Super Moderator
Dec 30, 2005
1,177
69
48
39
MKE, WI
Thanks. I bought that crowl trim piece as a set and it came with carbon fiber door skill plates (which I have yet to install) about 8 years ago on ebay. They don't really list these kind of products anymore that much but your best bet is this place. They are the cheapest and offer tons of cool products. I personally like the carbon fiber body moldings and going for that in the near future.

http://retrospec-toyota-supramk3.blogspot.mx/

Nice!, I was not aware of this company.
Could drop a ton of money on this stuff.

I am liking the exterior trim pieces, almost cheaper than finding a used set.
 

Abe's 1987

Member
Sep 5, 2017
253
10
18
Houston,TX
Nice!, I was not aware of this company.
Could drop a ton of money on this stuff.

I am liking the exterior trim pieces, almost cheaper than finding a used set.

My thoughts exactly. Everyone wants average $300 for a complete used exterior trim. They have new for a little bit more money. Might as well go for new.