speedtigger

iTrader: (16)

I was hoping some of you could help us conversion guys out. We would like to see a couple pictures of your heater control valves so we can see how it works.

Many of us in the conversion section either block off the heater hose ports or hook them up to our old car heater systems.

The question is, when the heater is turned off, does it merely block the circulation from flowing, or does it bypass the heater and send the water back down the return hose?

OldCobraGuy

iTrader: (2)

Funny you should mention that. I'm in the middle of trying to install a valve on my F body right now. I'm using the "van" bypass style valve (Four Seasons 74781) as I thought it might be important to keep the coolant moving when you shut it off to the core. I'm not so sure and I would love to talk to someone who really knows how the cooling system on this car flows. There are enough guys running around with the heater hoses completely blocked off that I can't imagine it's critical to proper cooling operation. I thought it might have something to do with proper thermostat operation, but I'm not sure. Again, I just don't know the system well enough.

On F bodies...and all LSx equipped vehicles I've seen, turning off the heater does not stop heater coolant flow. It will bypass it if you have that valve, or it will continue to run it through the core constantly and rely on the blend door to shut off the heat...which is stupid IMO. In fact, I was looking at an LS6 CTS-V and if they shut the heater coolant off on that car, you would have a real problem because the purge system is tied in by the heater core.

If anyone can post up a diagram showing the cooling system flow chart, I would love to see it.

joecar

From this thread: https://ls1tech.com/forums/advanced-...erheating.html

This is a "schematic" of coolant flow:

OldCobraGuy

iTrader: (2)

Ok. If I read that correctly, with a closed thermostat, coolant will still circulate in the block via the bypass if you have the heater hoses blocked off. I sent Joecar a PM for his opinion. I'll let you know...but it appears we can block the heater hoses off without a problem. that means we do not have to use a bypass valve and can use a single hose valve instead.

joecar

With the heater circuit shut off, the BP valve will open so you get coolant circulating around the block; the bypass takes 5 psi pressure difference across it to open, the pump is capable of doing this since the BP is the only remaining path; it might or might not take a little longer for the TS to open since the wax motor is located between the TS and BP (i.e. fed from the heater return).

OldCobraGuy

iTrader: (2)

Thank you very much for the post and the PM. I'm still set on bypassing the heater core. There is just no reason to have that heat in there. I have two valves I'm working with. One is a bypass style for GM LSx engines, and the other just shuts off one heater hose. It's a Ford valve and is a lot more robust than the bypass style. It also fits where I need it to. I want to try and make the bypass style work if I can though. But if I can't, I'll just shut off the return line from the heater core.

speedtigger

iTrader: (16)

It is good to understand why it works either way. That secondary plunger on the thermostat gets overpowered by water pressure in the event that the heater lines are blocked. However, the system is designed to have constant flow through the heater lines whether it is routed through the heater core or not. So, I think I will loop my lines until I install the heater core, then I will use a factory style bypass system simply because that is how it is designed to operate. Thank you JoeCar and all who contributed.

OldCobraGuy

iTrader: (2)

I finished mine yesterday. The bypass valve idea didn't fly with me. I couldn't find a GM or Ford valve that would seal. They all leaked past that cheap butterfly valve in there. So I installed an inline valve off a 99 V8 Explorer. Much more robust ball valve and it completely seals off the heater core. I installed it on the return to the pump. I drove it yesterday and didn't see any ill effects...but I'm going to watch it. If I had my choice, I would use a bypass. But since I couldn't find one that's worth a crap, I had to go with this set up.

Andy1

Hey OldCobraGuy,

I did a lot of research on the subject in order to get my conversion heater done properly. First, I would recommend using the bypass type heater valve (HV) in order to maintain flow just as GM intended. I had originally bought the Explorer HV as you did, but it's logic didn't suit what I wanted from it, and it has 5 ports so it gets messy dealing with that. I ended up with the stock Fbody bypass HV, though there's one improtant issue to deal with in order for it to function properly. Vacuum must be applied to the valve in order for it to bypass (or re-circulate back to the water pump). To allow the hot water to be directed to the heater core, vacuum must be removed (shut off) to the HV. In order to deal with this required logic, you need a vacuum control solenoid that is activated by the heater control when you want heat in the car. The soleniod is NO (lets vacuum pass through it), then closes (and vents) upon heater request. The solenoid you need is an EGR control solenoid from a 87-95 Chev/GMC truck, NAPA CRB 219226 (Echlin 2-19226). The HV water flow logic I have somewhere, but I need to look for it.
Hope this helps,
Andy1

S10xGN

iTrader: (11)

Personally, I think ya'll are overcomplicating this thing. I'm sure that's what GM intended, but it works just fine w/o circulating through the heater loop. Mine has a positive shut-off (Vintage Air) and I live in a very hot & humid environment.This has been done many times by many people w/o problems, so why add more (gawky) equipment and complexity? If you're that concerned, just drill a 3/16" hole in the t'stat for piece of mind...

OldCobraGuy

iTrader: (2)

Thanks Andy.

First though, where did you find a stock F body bypass valve? I didn't know one existed. GM has one, but it's not for the F body. I would be interested in seeing that.

By the way, every bypass type heater valve I've seen leaked. In other words, none would seal the coolant flow. The little butterfly valve they use just doesn't get it done. That was a deal killer for me.

As for vacuum control, I went about it an easier way (IMO). I simply spliced into the door motor that controls the air supply to the dash vents, bent up some plastic vacuum line, and ran it out to the heater valve. Now, whenever I have the HVAC system set so air flows out the dash vents (Max A/C, A/C, Vent), the heater valve closes. The only thing I lose is the ability to put heat out the dash vents...which is not an issue here in Phoenix.

OldCobraGuy

iTrader: (2)

Which is basically what I have done. Evidently, GM built a fail safe into the system by having a bypass built into the thermostat assy. And I can see where keeping the coolant flowing through the heater core would be advantageous...and something I would prefer to have. But I think you're right...I think we're fine without it as long as hot spots don't develop in the engine prior to the thermostat opening.

Andy1

The thermostat bypass block off plate (on the stem of the thermostat)already has four holes in it that would allow some amount of circulation internally in the water pump. Drilling a hole in the thermostat wouldn't really accomplish anything other that allowing some cold water to circulate through the motor at the exact a time you don't need it.

Andy1

speedtigger

iTrader: (16)

This is true for the people with cars that originally came with LS motors but, for us conversion guys with old school conventional radiators equipped with a fill cap, this could help get coolant into the block on a new fill up. Otherwise, we have to pull the upper radiator hose and pour the coolant directly into the upper hose to make sure the block fills up with coolant and not just the radiator.

b.rudy

iTrader: (1)

ResizedImage951384452381718.jpg

Reserrecting an old thread
I too am doing a engine swap and trying to decide how i want to run my heater control valve. My question is in the coolant flow pic from pirate4x4 , the tee fitting on the bottom of the surge tank... is that a straight through flow for the coolant which is also tee'd into the surge tank or does the coolant have flow into the tank first and THEN come back out of the tank to complete the coolant flow?