Vortec 454 Heater Core Bypass

[FourEightZero]

Reviving a little bit of an old discussion here...

Does anyone else have trouble finding a heater core bypass valve that doesn't start leaking? All I seem to find are cheap plastic ones. I had one nearly cost me my engine once when it broke in half without warning on the interstate, dumping all my coolant in a couple seconds. New ones seem to last a couple years at best before they start dripping from a joint or the shaft itself. I have a 1996 5.7 Tahoe BTW, no rear heat.

I just installed this setup this weekend, went for a cruise this morning with the heater core shut off. Turned the heat on in the cab and it was blowing ambient temp. Engine was staying at ~205°

About $60 of plumbing parts.

 

[454cid]

I just installed this setup this weekend, went for a cruise this morning with the heater core shut off. Turned the heat on in the cab and it was blowing ambient temp. Engine was staying at ~205°

About $60 of plumbing parts.

I like how you used the clamps/hangers to secure the valves. My plan is to just dead head the flow, and I was going to mount the valve right on the intake manifold with a short pipe nipple, but found that I would have to use a longer nipple for clearance. I never finished the project after that. I've been thinking I may just put the valve where you have yours, but pad it somehow, so it's not bouncing around.

You've got both valves open in that picture.

 

[FourEightZero]

I like how you used the clamps/hangers to secure the valves. My plan is to just dead head the flow, and I was going to mount the valve right on the intake manifold with a short pipe nipple, but found that I would have to use a longer nipple for clearance. I never finished the project after that. I've been thinking I may just put the valve where you have yours, but pad it somehow, so it's not bouncing around.

You've got both valves open in that picture.

Yeah, my plumber roommate pointed that out too. Both handles pointed vertically during the summer, point em both back toward the firewall in the winter.

 

[Schurkey]

Why would you install TWO valves?

You only need one to shut-off flow to the heater core.

 

[FourEightZero]

Why would you install TWO valves?

You only need one to shut-off flow to the heater core.

So which one of those was not needed?

 

[Schurkey]

The one that's not in the supply hose from engine to heater.

I can't tell how the system is plumbed from that photo. I'd need to see the other ends of the hoses that aren't in the picture. Kinda thinking the red one goes to the front of the intake manifold, and the black one to the radiator.

If that's the case, the valve between the red and black hoses does nothing useful. If it's closed, it could just as well be removed along with the "Tees". If it's open, (as shown in the photo) it's short-circuiting coolant flow through the radiator core. That would make the cooling system less efficient because all the coolant going through that valve DOESN'T go though the radiator core. Important? Maybe not. That coolant flow would have gone through the heater core and into the radiator "cool" tank anyway, based on the OEM routing. Point is, it's extra expense and extra complexity, and a lot more potential leak-points that serves no useful purpose. (You wouldn't need ANY of this, if the air doors in the air-delivery system sealed properly.)

Failing that, all you actually needed was one valve, two hose-barbed-to-pipe-thread fittings, and two hose clamps. Secure to the fender as desired. All the rest is just dead weight.

In MY driveway, I'd not have used unshielded worm-gear clamps because they're hard on the hoses and promote hose damage.
Example: Fuel pump hose with unshielded worm gear clamps and their alternative.

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I'd have used smaller, proper-sized clamps for the hose diameters.

 

[FourEightZero]

The one that's not in the supply hose from engine to heater.

I can't tell how the system is plumbed from that photo. I'd need to see the other ends of the hoses that aren't in the picture. Kinda thinking the red one goes to the front of the intake manifold, and the black one to the radiator.

If that's the case, the valve between the red and black hoses does nothing useful. If it's closed, it could just as well be removed along with the "Tees". If it's open, (as shown in the photo) it's short-circuiting coolant flow through the radiator core. That would make the cooling system less efficient because all the coolant going through that valve DOESN'T go though the radiator core. Important? Maybe not. That coolant flow would have gone through the heater core and into the radiator "cool" tank anyway, based on the OEM routing. Point is, it's extra expense and extra complexity, and a lot more potential leak-points that serves no useful purpose.

All you actually needed was one valve, two hose-barbed-to-pipe-thread fittings, and two hose clamps. Clamp to the fender as desired. All the rest is just dead weight.

In MY driveway, I'd not have used unshielded worm-gear clamps because they're hard on the hoses and promote hose damage. I'd have used smaller, proper-sized clamps for the hose diameters.

Noted.

Red hose in lower RH corner comes off manifold, hot coolant headed toward heater core. Black hose is return to radiator from heater core.

My thinking behind 2nd valve was to ensure all hot coolant goes to heater core when 1st valve is open. It may be overbuilt, but I knew it would work. I guess I will find out how durable this setup is.

Plumber roomate says it's a solid setup.

I've seen those type of worm gear clamps on hoses that have lasted well over a decade. Not concerned with it

P.S. I wanted the "H" bypass setup to ensure there is always coolant flow from manifold to radiator.

 

[Schurkey]

Noted.

Red hose in lower RH corner comes off manifold, hot coolant headed toward heater core. Black hose is return to radiator from heater core.

OK, that's what I expected.

My thinking behind 2nd valve was to ensure all hot coolant goes to heater core when 1st valve is open. It may be overbuilt, but I knew it would work. I guess I will find out how durable this setup is.

But if there were no connection between the two hoses, all the hot coolant would have to go through the heater core anyway.

The second valve has no purpose.

Plumber roomate says it's a solid setup.

Solid assembly and mounting does not mean "smart/elegant/efficient design".

I've seen those type of worm gear clamps on hoses that have lasted well over a decade. Not concerned with it

Ok. As long as you recognize that the OEMs don't use those unshielded clamps, and there's reasons why they avoid 'em.

P.S. I wanted the "H" bypass setup to ensure there is always coolant flow from manifold to radiator.

There's NO good reason or benefit to always have flow from manifold to radiator. The only reason GM allows that is to save the cost of the shutoff valve and the control system. GM did install a shutoff valve in some applications, and then the system deadheads just like I'm suggesting. That valve would have to be opened to allow heat, and opened when the cooling system is serviced. Otherwise it can be deadheaded.

If the cooling system were modified to eliminate the OEM bypass (on the Vortec it's done with the intake manifold, hose, and the water pump) then what you have could be useful.

 

[FourEightZero]

OK, that's what I expected.


But if there were no connection between the two hoses, all the hot coolant would have to go through the heater core anyway.

The second valve has no purpose.


Solid assembly and mounting does not mean "smart/elegant/efficient design".


Ok. As long as you recognize that the OEMs don't use those unshielded clamps, and there's reasons why they avoid 'em.


There's NO good reason or benefit to always have flow from manifold to radiator. The only reason GM allows that is to save the cost of the shutoff valve and the control system. GM did install a shutoff valve in some applications, and then the system deadheads just like I'm suggesting. That valve would have to be opened to allow heat, and opened when the cooling system is serviced. Otherwise it can be deadheaded.

Yeah well forgive me for not taking what random people are saying on the internet as gospel. This is my coolant bypass and I have seen from other people on these forums and experienced people IRL that you want flow out of the front of the intake manfold when the t-stat is closed.

It flowed like that with the OEM setup, and it does now.

Now I don't have a hot heater core right next to my AC evaporator when I'm trying to keep my cab cool.

Thanks for your input.

 

[Schurkey]

This is my coolant bypass and I have seen from other people on these forums and experienced people IRL that you want flow out of the front of the intake manfold when the t-stat is closed.

The Vortec engine has flow out of the front of the intake manifold when the thermostat is closed. That's part of the OEM coolant bypass system.