Heater core bypass, stupid?

[rob249]

Truck is a 1994 GMC Yukon 4x4, 2 door, TBI.

Is there any benefit to be had by adding a ball valve to the heater core inlet? From what I understand, you don't need to bypass on our trucks, ie, water doesn't need to flow through the heater core. I know there is a blend door that should, in theory, isolate the heater core from the cold AC, but there is still a hot heater core in the cab.

My AC is blowing very cold, it'll freeze your **** off on the highway, but any extra cooling to be gained would be very helpful, It is VERY hot here.

Ill be changing over to the AD244 alternator and adding some helper fans to the condensor in a couple weeks, figured I might want to do this at the same time.

Anyone tried this with actual results? Thanks all.

 

[caw_86]

i think @L31MaxExpress put a manual ball valve in to block the water, its also hot here in texas a hot heater core is the last thing i want in the summer, my PO deleted the pnematic valve and ran straight hoses, so it was always on. i plan on putting a valve in when i reinstall the my custom made hoses

 

[Schurkey]

One concern--and it may be moot in hot weather--is that the hot water going through the heater core is the same hot water that's warming and stabilizing the temperature of the intake manifold. If you BLOCK that circulation, MAYBE you'd have some problems with poor fuel vaporization as the engine warms-up. I don't know, never tried it.

You could BYPASS the heater core without blocking the "heater" circulation, and maybe that's the preferred solution. Or, maybe not. Again, I haven't played with this.

 

[99xcss4]

did it once on a 98 gmc jimmy heater core failed so took both heater hoses off and connected them to each other to complete the loop

 

[rob249]

What I've read on other forums, for different vehicles, is that bypassing seals off the heater core which could cause a vacuum in the heater core as the fluid trapped in it cools. This could cause leaks, or so I've read

 

[99xcss4]

What I've read on other forums, for different vehicles, is that bypassing seals off the heater core which could cause a vacuum in the heater core as the fluid trapped in it cools. This could cause leaks, or so I've read

I do not know any thing about that but the one that I did we just left the the tubes for the core open since it was bad and leaking and connected the 2 heater hoses to each other or took one hose completely off and ran the other hose to where the one that was removed was at I forget it has been a very long time now

 

[GoToGuy]

If the cooling is adequate, changing anything does not benefit you. In point may cause other problems, with static, no flow. And more connections only adds more possible failure points.

 

[rob249]

If the cooling is adequate, changing anything does not benefit you. In point may cause other problems, with static, no flow. And more connections only adds more possible failure points.

That's really the question, if that would cause flow problems in the block, or lack there of. The cooling is adequate, at speed, less so in traffic. I really wish the computer would raise the idle speed when the ac is on, all it does is maintain 500 rpm no matter what.

 

[caw_86]

What I've read on other forums, for different vehicles, is that bypassing seals off the heater core which could cause a vacuum in the heater core as the fluid trapped in it cools. This could cause leaks, or so I've read

This is why isolation valves go on the return leg, so when you isolate it it blocks the core full of coolant

 

[GoToGuy]

Do you have the aux fan mounted in front of condenser? GM added the aux fan in front of condenser to add airflow at low, no speeds, to improve AC performance.
Your idea of adding shutoff valves is really a " feel good " idea. Before you tear apart the heater lines. Are you aware that GM already utilized this idea in certain model Tahoe's and Suburbans ? It reduces water through heater when AC cooling is in demand . A better idea.
Isolation of return leg? It's not just a water pump. It's a closed pressurized cooling system, not quite the same. But as always you free to whatever you want.