I have swapped a EJ into another car and currently have the tubes that normally run to the heater core looped back into themselves, because I have not figure out my heating system in the car.  

 

I'm wondering if those tubes need to flow constantly or is it possible to use a restrictive valve to control the flow to the heater core, in turn reducing the amount of heat in the car?

 

Or am I going to need to figure out a way to keep the coolant flowing but still keep the hot coolant out of the heater core?

 

 

ok to loop. No restrictor needed. Just make sure the clamps are tight and that the hose doses not kink.

 

o.

Yes the coolant needs to keep flowing to allow the thermostat to regulate the engine temperature.

 

There are a few options. You can install couple tees and do a bypass; you can restrict that bypass somewhat but not that much. You can get a Tom Shiels thermostat housing and use this for the bypass. Or you can use a 4-port heater valve that allows fluid to flow around the heater core when off.

 

On my Vanagon conversion I have a simple bypass, and the heat is still decent.

You can NOT put a valve in the heater core loop. That loop is an integral part of the cooling system. Blocking it can lead to overheating, especially in cold weather.

 

if those tubes need to flow constantly

in the EJ cars, legos imprezas and foresters, they do flow freely all the time to the heater core.

 

but it would not surprise me if you could alter the t-stat,

cut a hole in it to allow more water to flow when closed,

and accomplish the same thing.

(the heater hose represents X% of the total flow, it's a math problem.)

 

it would also not surprise me to learn that the EA cars did it the same way.

 

what car did you swap into??

I was pretty sure I knew that it had to flow consistently, I just want double check.  

 

Oddly enough what I had drawn up today in cadd while i was bored at work was basically what ended up being a 4 port heater valve.  It allows flow to happen 100% of the time, it just either runs it through the heater core or it loops back to the engine.  Either I'll explore the 4 port valve or I'll explore something with a valve in a T.

 

Sorry for the lame picture, but this is what I drew.  

 

 

The red arrow indicates a valve that could swing between the two openings.  With some online searching, most Ford rangers, areostars had those factory, although controlled by a vacuum actuator so I may try to find one that is manually controlled.  

 

 

 

what car did you swap into??

 

1st gen Mazda Rx7, and I'm putting a summit heater box in it.

Edited September 18, 201411 yr by mellow65

Adding valves complicates things. Let the coolant just run through the core. The blend flap directs air away from the heater core when heat isn't needed, so hot air will NOT blow into the cabin.

Most Asian cars are set up to work that way, I would be surprised of the Mazda air box doesn't work the same or nearly the same.

There is nothing left of the Mazda heating system. What I'm replacing it with is a basically a heater core with a squirrel cage fan behind it. I'm making do with what I have in front of me.

EA81 cars actually had a bypass valve built into the heater box.

 

Same concept as your drawing.......flow into the heater when you want.....full bypass around heater core when switched.......always full flow to the engine.

 

Adding valves complicates things. Let the coolant just run through the core. The blend flap directs air away from the heater core when heat isn't needed, so hot air will NOT blow into the cabin.
Most Asian cars are set up to work that way, I would be surprised of the Mazda air box doesn't work the same or nearly the same.

 

He won't have a blend door.....and as anyone living in hot weather climates without A/C can tell you.........a full flow heater core still warms the car.  I can feel the area at the bottom of the console radiating heat on warm days, even with the blower off and blend door on cold.

 

There can definately sometimes a need to "turn off" the coolant flow to the heater core.

 

That said.......the valves are often one of the things that starts leaking.........and losing coolant is worse than being a bit warm or cold.....so it's a risk to install a valve.  Probably why subaru gave up on them in starting with EA82s