Heater core - shutoff valve or bypass valve?

[0stones0]

I’ve asked this question in another thread and get conflicting answers. I’m planning on using one of these options to better control the heat sink that occurs with the heater core, during times of using the air conditioning. As well as being able to keep my blend door switch away from max cold to possibly save the door from damage.
I plan on using an electric bypass valve that I can control from the interior for ease of use. I live where during the riding season, we can have cool and warm days and I don’t want to be popping the hood for adjustment.
My .02 is that a bypass valve is necessary based on this quote from another forum:
“For those that don't know, the LS motors need a circulation of water back even if the heater core flow is turned off (during AC usage). If you don't use a 4 port setup, you may be in for some wierd overheating issues. If the AC HCV relay is on when you start the car, no warm water will get back to the thermostat housing if your just idling, etc.....”
I’d rather be safe than sorry.
This is the bypass unit I plan on using:
Electric bypass valve

[MSgt O]

This indeed WAS answered in the other thread. IF you block off, or whatever divert, water going to and coming from your heater core, nothing temp wise in your car will change. The issue I see, is if your BLOCKING off a hose from the waterpump TO the heater core, you will have an increase of pressure constantly in that hose. In the Aircraft world, you dont want unused pressure sitting there, in a line static, so we recycle it back to the pumps forming a "pressure and return loop". Your concern about overheating was addressed, it will not. However, me personally, if you can find a vlave that loops the water back to the motor, BEFORE your heater core, instead of just a "shut off valve" that would leave pressure from your water pump in a static hose, that would be the best option. Looking at that valve you linked, it is a bypass valve and would be perfect for what you want to do.

[0stones0]

Originally Posted by MSgt O

This indeed WAS answered in the other thread. IF you block off, or whatever divert, water going to and coming from your heater core, nothing temp wise in your car will change. The issue I see, is if your BLOCKING off a hose from the waterpump TO the heater core, you will have an increase of pressure constantly in that hose. In the Aircraft world, you dont want unused pressure sitting there, in a line static, so we recycle it back to the pumps forming a "pressure and return loop". Your concern about overheating was addressed, it will not. However, me personally, if you can find a vlave that loops the water back to the motor, BEFORE your heater core, instead of just a "shut off valve" that would leave pressure from your water pump in a static hose, that would be the best option. Looking at that valve you linked, it is a bypass valve and would be perfect for what you want to do.

Definitely understand what you’re talking about with the static pressure. I work on DC3’s from recip engines to turbines and see it from both standpoints.
You state that there isn’t a heat issue with the shutoff but, you recommend a bypass, regardless, although for a different reason. Other opinions out in the internet world state there can be heat issues and I’d rather be safe than sorry. Lots of opinions to look at and I appreciate yours, as well.
Price for an electric shutoff vs. bypass is negligible. Bypass is my recommendation, as I believe is yours.

[MSgt O]

OK, from a mechanical standpoint, look at it this way. All you are doing is simply removing the water flowing through the heater core, thats MECHANICALLY all youre doing. How, if you look at the water flow through that system, could that possibly upset temperature of the motor? Water is still flowing properly, just not through the heater core. Your thermostat controls the internal temp of the water being heated in your motor, and opens and closes to ensure proper operating temps. How possibly could adding a bypass valve, and removig the heater core from this coolant loop, affect anything? perhaps, JUUUUUUST possibly, you would lose what, a couple of quarts of coolant "trapped" in the heater core and associated lines? Ive been a mechanic my whole life, and there is just no possible way redirecting water flow like this can change engine temps. Mechanically not possible. Hydraulically not possible. Take everything you read with a grain of salt, but in your experience, and mechanical apptitude skills, you know what I am saying is correct.

On a different note, I restored a DC3 we had on static display at McGuire AFB. Still had the R1830s intact on it. Not a recip guy myself, Turbo Fans and turbo jets mostly, but my pops was an R4D plane captain in the Navy at NAS Twin Cities back in the day.

[0stones0]

And more than likely you’re absolutely correct. I’m just going with, let’s not take any chances. Nuff said.

We did “Thats All Brother” a couple years ago. Full restore. Lead D-Day plane.

[0stones0]

Got the valve today and did a quick look see on where a possible install spot could be. Looks like it would clear the hood when closed and basically just cut the hoses and install. Would be slight farther to the right than where it’s sitting now, lined up with hoses. Tentative for now as it’s colder than a witch’s, you know what, out there.

[MSgt O]

Yeah, I know that witch...she is parked outside and hasnt left in AGES....Looks like a good spot for it. Good luck!

[0stones0]

Originally Posted by MSgt O

Yeah, I know that witch...she is parked outside and hasnt left in AGES....Looks like a good spot for it. Good luck!

She’ll probably be hanging around for awhile yet.

[rdavis]

I bypass my heater core in the warm months. My blend door is jacked up ( I know I should fix it. lol) It just blows warm air. So I just went to Orilleys & found a "U" shaped hose. It goes to the heater hose barbs on the water pump. So I believe I still have proper circulation of water. Been doing this for 2 years now with no issues, Temp runs the same as normal.

[camguynj]

Originally Posted by 0stones0

Got the valve today and did a quick look see on where a possible install spot could be. Looks like it would clear the hood when closed and basically just cut the hoses and install. Would be slight farther to the right than where it’s sitting now, lined up with hoses. Tentative for now as it’s colder than a witch’s, you know what, out there.

How difficult was it to get the heater core hoses off?

[0stones0]

Originally Posted by camguynj

How difficult was it to get the heater core hoses off?

Haven’t attempted anything yet. As stated, way too cold to even think that far ahead. Don’t think I’ll be removing the hoses, just cut what I need out and install valve.

[camguynj]

Originally Posted by 0stones0

Haven’t attempted anything yet. As stated, way too cold to even think that far ahead. Don’t think I’ll be removing the hoses, just cut what I need out and install valve.

Ah, I now see that you just positioned the valve by the heater core. Good luck when you get to it.

[0stones0]

Got my switch bank wired up and in place under the dash, far left.
Left to right: Dash Cam switch - Toggle switch for power on/off to the potentiometer - Potentiometer switch to the valve.

I know where the wire will go under the hood. Just need to man up and cut the hoses! Soon...

[0stones0]

Wires under the hood. Came out just above the power cable through the firewall. Then out to the passenger side, by the hose connections to the heater core.