1988GTA500HP

The coolant diverter valve adds a whole lot of uglyness under your hood. I have read many threads about it being removed from members cars. Mine was removed, as was the heat.

Wanting to get heat back in my car (mostly for the defroster), I started researching hose routing on this forum. I found where some members used a manual valve to shut off the heater core during the summer. I liked this idea and quickly went to Home Depot.

I continued researching while I was waiting for the weekend to install my new heater core. I came across many claims that the advantage of the diverter valve is it keeps hot coolant out of the cabin (heater core) during the summer using vacuum from the AC/heater controls. No manual valve turning. Seemed reasonable. So off to the JY I go.

I got the newly acquired valve home and wanted to make sure it was functioning before plumbing it. I applied vacuum to it and to my surprise, while it does open up the bypass leg of the valve, it doesn't close off the heater core leg. I'm sure not all the coolant is going to go through the bypass leg. That said, it appears to me that it only REDUCES the flow of coolant to the cabin, not eliminating it. So now, I will go back to the manual valve as it is definitely more effective.

Pic 1 no vacuum. Pic 2 vacuum applied.

norcalz28

iTrader: (13)

It seems that when the valve is "opened," hot, uncirculated coolant is allowed to pass into the the heater core, where as normally it would get coolant from the radiator which would be at a lower temp than coolant coming right out of the intake manifold. Funny, I was messing with this same valve tonight and wrestling with the idea of keeping it or replacing it. I think I will relocate it somewhere a bit less visibile, but I will retain it for now.

Will

1988GTA500HP

Hey Will. Now I get it. I always thought the coolant flowed the other direction. When the valve is open, the coolant flows from the heater core to the valve and back to the heater core input line instead of back into the intake manifold. So it still feeds coolant from the radiator to the heater core but it is diluted with coolant that has already been passed through the heater core. Correct?

norcalz28

iTrader: (13)

I'm pretty sure that's how it flows`

1988GTA500HP

That is what you said. I was just trying to simplify it so even I could understand. So my assumption still stands, some of the heated coolant still goes through the heater core with the A/C on. I guess that has the advantage of not letting coolant stagnate in the heater core and rust it through. But I just installed an aluminum one so I'm not too worried about that. Thanks for your help.

norcalz28

iTrader: (13)

Just change the coolant regularly and you shouldn't have a problem unless it's a manufacturing defect

LAFireboyd

iTrader: (3)

I hope you guys don't mind me jumping in here, but flow runs the other direction than what (I think) you're saying. No flow comes from the radiator to the heater core. It runs from the heater core to the radiator.

The next time you drain/flush the radiator, watch the flow upon initial refill of the radiator at start-up: cap off, engine running, warms-up, thermostat opens, flow begins, coolant level in the radiator drops as it's sucked out of the bottom and into the water pump, and coolant from the heater hose that's connected to the radiator(below the filler neck) flows into the radiator.

To get to the heating system, flow comes out of the intake manifold, up into the bottom of the throttle body, out the side of the throttle body, into the heater valve, where flow can be split by the valve: the upper hose always flowing directly back to the radiator, the valve(when open) diverting some flow to the heater core through the lower hose. Then the other hose at the heater core flows out and returns to the radiator, along the way joining up with the flow from the heater valve's upper hose, now altogether making way to the radiator, where it mixes with cooler coolant in the radiator, then begins its journey all over again.

If you're bypassing the throttle body, then remove the U-shaped hose and run a hose from the manifold to the heater valve. If you're bypassing the throttle body AND deleting the heater valve, then the hose would go from the manifold directly to the heater core. And if you're bypassing the throttle body AND bypassing/deleting the heater core completely, then you can remove all the heater hoses(to and from the core), plug the manifold and cap the radiator return port.

1988GTA500HP

That was what I thought, LA, but I'm certainly not an expert. My reasoning for this was threefold:
1. The return line wouldn't be smaller than the feed line (pressure issue),
2. Coolant returned to the radiator should be at the top using gravity to run it through the cooling fins, and
3. The heated coolant from the engine would be best to feed the heater core.

I know for a fact that the upper hose on the valve is the one that is vacuum operated (see pic in 1st post). What I don't know, because I apparently have a vacuum leak in the cockpit (it's now on my list), is when vacuum from the heater controls is applied. The default setting on the valve is closed with no vacuum. Does this mean that when the temp slider is moved to COLD then vacuum is applied? Or is vacuum always applied until you move the temp slider to WARM? Once I get under the dash I may be able to resolve this. In the meantime,

Pic 1 from plenum version.
Pic 2 to plenum version.

Anyone know if either of these are correct?

norcalz28

iTrader: (13)

I just ran a bypass to get my engine started the otherday, and coolant flows through the intake manifold, OUT of that little nipple in front, towards the rad/heater core, whichever way you have it routed. Unless my water pump is turning the wrong direction, I think it's right

1988GTA500HP

So pic 1?

LAFireboyd

iTrader: (3)

Yes, pic 1 is correct. The coolant flows from out of the intake manifold through the U-shaped hose to get up into the throttle body, exiting the throttle body as shown in pic 1, then continuing as shown.

The valve to control the flow to the lower hose is in the upper hose, but it's the lower hose that's "controlled," being closed-off and opened-up by the valve. When the valve is open, coolant is released to the lower hose, where it flows to the heater core. And when the valve is closed, no coolant flows to the heater core.

1988GTA500HP

Thanks guys. Seeing the door that opens and closes in the top hose made me think that was the controlled route. You learn something new every day.

thunder69n

Was making sure I understood this correct to bypass mine, but I was able to find a new one before had to drive it again

g wood

I just recently did some relocating of the bypass valve on my car and like the way it turned out. I wanted to attach a pic but am not smart enough to do so. If some one can tell me how this is done I will post one

travis401

iTrader: (1)

coolant flows from the intake, into the divirter valve, it then flows in 2 directions, into the radiator, and into the heater core. if the valve is shut, the flow to the heater core is shut off and it only flows into the radiator. older cars dont have a bypass valve and water flows out of the pump or intake into the heater core and to the radiator. i removed the diverter vavle and have mine set up like that. simple, easy, and the cabin isnt any noticably hotter.

l_dis_travlr

g wood:

When posting a reply, scroll down to the "Additional Options"
section, select the "Manage Attachments" widget. This opens
a separate dialog box. Select "Browse", then navigate to the
source file (*.jpg, etc.). After the path is in the box, select
"Upload" and then wait. It won't appear in the edit box, but
should be visible by "Preview Post"

Now post some pic's!
(Show me yours, & I'll show you mine. )

TreeFiddy

Mine is one of the older ones, without the valve. My heater was never hooked up when I bought the car, decided to finally connect it a couple of years ago.

I agree, doesn't seem to make the cabin any hotter than before, even in the summers we get here. The core is hidden behind that blend door, which seems to block it effectively when closed. I was going to hook up a less obtrusive vacuum valve from a Falcon, but decided it was good as it was.

Surprisingly, it helps with engine cooling noticeably too, as a bonus.

g wood

Thanks for the info I have tried attaching three pics. If they work you can see the valve between the ac acumulator, air pump controls and the air injection lines to the headers. I did not have to buy any diferent hoses to make it work. I just had to just switch them around and shorten up a couple. The hardest part was moving the air pump relays foward closer to the compressor to make room for the new valve location. It required cutting the steel line conecting thecontrols to the pump and fabricating my own . It requires that you know how to solder and braze a little

l_dis_travlr

And here's some pics of mine.
It may not be to visible, because I mounted it down low
on the frame rail. But the valve & T-fitting are both
tucked away down there.

Bigal1529

How did the relocate turn out and where did you put it?

Gunnyj1

Sorry to re birth this thread but I didn't want to start a new one. Can someone post a recent picture of the brass ball shutoff valve installed? I have a 91 camaro rs, 305 and would like to do this. Also my plan was to remove the diverter valve completely and install a tee then add the brass ball valve to the hose leading to the heater core inlet. Has anyone done that?

Gunnyj1

One more question. Did anyone get rid of the metal pipe and just used a heater hose?

Drew

iTrader: (58)

You could delete the hard pipe, but why would you want to? A rubber hose hanging off the heater core has to be supported anyway, to keep the vibration from breaking the inlet/outlet solder joints. Not to mention the hard line moves the line out of the way.

mmadden55

You can run the valve in either the inlet or return heater hose line it doesn't matter either way it stops the flow through the heater core.

Gunnyj1

Yeah, I was just wondering if someone has done it (in respect to the pipe line). I have a few ideas that I'm thinking and one included replacing the pipe line with a heater hose. If I did I would make sure it's supported and secure. My main concern is to replace the diverter valve with a 3 way tee and then add the brass shut off valve
. Thanks for the quick response folks! Would still like to see a pick of someone's valve though.

mmadden55

all you need is a pass through with a shut off valve in either heater hose line I ran it that way in my 89 GTA

Gunnyj1

Gunnyj1

I screwed up something when sending the pics! Anyway, the pics above is what I came up with. I hated the way the diverter valve looked and I liked the fact that I can control the coolant flow to the cabin manually. So I bought a 5/8 tee connector, 5/8 straight connector, U molded hose and a 5/8 brass ball shutoff valve. Cut some of the hoses down and that's it!

Gunnyj1

One last question. Should I refill the system with the shut off valve open, then close it, or should I refill the system with the valve already closed.

MacRocZ

Is that how you ended up running it? My 89 had the heater changed before i bought it. it has a shut off valve on it as well that has always been closed off. i let the car run and got no heater after opening the valve. car didn't get up to temp as i had other things to do. i imagine it has to circulate water thru system before i start feeling heat correct?