Andy1

I went through this once before, but thought I'd re-address the heater valve issue in case there's some new information that someone has come up with.

For a proper heater valve, it requires that a bypass type be used to keep coolant flowing through it and back to the waterpump when in its closed position then of course allow coolant flow to the heater core when in an open position. I have been unable to find information on a stock '01 Camaro heater valve (GM P/N or aftermarket P/N), whether it's vacuum operated, suitable for conversion cars, or?? I've never seen the Camaro valve; anyone have a photo of one? I've read that a heater valve from a '90 Astro will work, but is it actually a bypass type? I seem to recall it wasn't. I have a heater valve from a '98 Explorer that is a bypass type, though it has an extra port that I'm not sure what it's originally used for. I need the vacuum operated type for my application.


'90 Astro valve; '98 Ford Explorer Valve


Thanks a bunch,

Andy1

bczee

iTrader: (12)

I am using one from a mid-80's on truck.. it has four ports on it that will bypass or switch to flow to the heater. It is vacuum operated from my Chevelle's EVAC control panel. I can take a picture of it after work today if needed and see if I can find the part number. Most good parts stores (not Autozone or Kragen) will be able to find something that will work..

ghettocruiser

iTrader: (17)

I dont think the LS1 4th gens had heater control valves... My 99 donor car didnt have one. I dont even knwo where they'd plumb one in the way the coolant lines are ran. The two heater core lines are sort of joined together with an alum bracket, and they run side by side up the chassis rail. There is nothing inside the HVAC box, because inside there its very similar to the older thirdgen style boxes.

I had to figure out a solution for this because the thirdgen HVAC box has different blend doors that makes the valve pretty important. I think the 4th gen boxes handle it differently and they make out ok with blocking the heat off internally.

I found a valve that has been working good for me so far. It works off my thirdgen's original vacuum supply for the heater control valve. No vacuum and it lets coolant flow through the core like it wasnt even there. When vac is applied, its allowed to come from the pump, loop around and go right back to the pump without going to the heater core. A little coolant might be leaking through and heading for the core, but its not much, and my heater lines stay way cooler after the valve than before.

Here are the pics and the part number for hwat Im using. Since it was on the shelf at autozone, Im guessing its probably off of some older van or truck or sedan.









Pretty easy to tuck away too.



And for absolutely no reason at all...a youtube video of the valve opening and closing...haha.

http://www.youtube.com/watch?v=yKN14bJEDmc

J.

eseibel67

iTrader: (10)

4th gens do not use a heater valve. They divert the heat with a door.

On the attached link, you can select a diverter valve for a custom application. Simply click:

PART NUMBER, then ATTRIBUTE SEARCH. It will give you the coice of any heater hose size you want, and well as if you want it to operate by cable, vacuum, or electrically.

http://www.4s.com/Online%20Catalogs-...g/Content.aspx

Andy1

Ghettocruiser,
Wow, thanks for the info/video!!
Would you mind posting the logic circuit in the blow photo? Top left I understand to be the hot source comming from the waterpump. Which is the bypass back to the pump, etc? Vacuum off = heater, or is it vacuum on = heater?

eseibel67,
Thanks for the link. I looked up the part number (74781) that Ghettocuiser shows in his photo and there it was. Thanks also for pointing out the attribute search; makes it easy to find what you need.

Guys, this is exactly the info I was looking for.

Andy1

bczee

iTrader: (12)

Didn't get time to look or take a picture of mine. but it is pertty much the same one as Ghetto is using. If I get home in time tonight... I'll get a picture or two posted.

bczee

iTrader: (12)

Here a a few photos of my setup.. Not sure who made it.. still looking..





I did have one fail on me.. was leaking from the control arm. .but it lasted 4 years before it failed.

Andy1

bczee,

Thanks for the photos. Still trying to get my head around the flow logic. In yours and ghettocruisers photos I see the flow arrow on the valve; is that the return from the heater core (3/4" hose at the top of the valve)? The hot supply from the water pump is the 5/8" hose on the bottom of the valve?

Thanks
Andy1

bczee

iTrader: (12)

The flow will exit the pump via the 5/8" into the control valve. it it is open, then then flow into the heater cord and then returns via the 3/4" hose/ports.

If the control vavle is closed, it will route the water from the inlet 5/8" port to the out let 3/4" port of the valve and therefore bypassing the heater core and return the water back to the pump. See Getto 4 pictures.. there is a butter fly valve in the middle controlling the route of the flow.

The arrow is the return flow direction from the heater core. Remember that the smaller line/hose is always the pressure or feeding side and the larger line/hose is usually the return side.

Andy1

So I went and bought the above heater control valve (74781), but it may present a problem if I understand the operation correctly; in other words I still need some advice

In its normal no vacuum state, it appears that the valve allows coolant to flow to the heater core (Heater core supply in and return are on the right side of the valve in your middle photo). With vacuum applied, the valve closes the flow to the heater core and simply directs the hot water through the valve and back to the water pump (the two hoses on the left side of the valve in your middle photo). Do I understand this correctly?

What I need for my Hot Rod heat/cool system is a valve that sends hot water to the heater core when vacuum is delivered to the valve (vacuum on, heater on). The valve in your system appears to do the opposite (vacuum on, heater off). Does your valve actuate when the motor starts?

Thanks for hanging with me on this.
Andy1