Certainly, the topic of heat inside a C3 has been discussed a number of times.  I know some folks have discussed the bypassing of the heater core, but I glanced around and did not find one specific post to discuss the process.  So, how do I go about doing this in the best way to try to keep the heat out of the passenger area?

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I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!

This is the Link ..  I did it when I replaced my heater core which was when I replaced my dash.  I can provide pictures if you need or want them.

If the link does not work it is on the top of the forth page on the "C3 Cooling and Heating Systems" forum.

(inserted clickable link)

Adams' Apple2009-06-07 12:15:00

Hey Marshall,

The inline positive shutoff valves work great and it's not complicated once you drain off the coolant. Just cut in to each hose and install a valve, clamp them back on and your all set. Leave open for winter and off during the summer. I did mine down low on the hoses before they enter the fire wall so they were less noticable. 

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Jimmy B.
Just can't wait to get on the road again.

 
                             Click to see larger views!

You know, as common as this problem is, I'm surprised Mid America and the other vendors don't have a "package" solution.  Years ago, I simply did a bypass of my heater core in my 76 Grand Prix by taking the two heater hoses and running them from one to the other with a metal fitting.  Anyone done anything like that? manget12009-06-07 13:55:23

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I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!

I actually prefer to tie the two hoses together. If what you're trying to do is remove heater core heat from teh passenger compartment, it's the only way to completely eliminate heat transfer. Even with the shut-off valves in both lines, heat will still transfer from the engine-side hoses thru the valves...it's called convection heat. Just because water(coolant) is not circulating thru the core doesn't mean the heat is gone...just diminished.
Do the shut-off valves help? You betcha. But disconnecting the hoses entirely eliminates the heat transfer completely.
It's six one way and half a dozen the other...


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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

That's exactly what I'm hoping to do Joel!  Anyone know of a part out there designed for that?  Back in the day, I just looked around the shop, but that was a long time ago...

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I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!

One problem will be that the two hoses are different sizes...on is 5/8" id, and the other is 3/4" id. I've used 5/8" pipe, and the 3/4" hose will clamp down it it. It's a bit harder to get the 5/8" hose to stretch to fit a 3/4" pipe...
Your local hardware store will have the part you need...just don't tell them it's for a Corvette...they'll jack the price up...


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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

One - Thank you Marshall, I actually logged on to ask this question today. Ted and I took the Vette to Madison to see Jeff Dunham (awesome show, front row seats)  and on the way home he said how can you drive in this car, it is so uncomfortable and I said it isn't cushioned that bad and he said "MY ASS IS HOT!" My car is definitely hot and not the way I want it to be. My feet burn have the time. '

Is this the valve everyone is talking about??? dsireme2009-06-09 08:49:41

[QUOTE=dsireme]Is this the valve everyone is talking about??? Adams' Apple2009-06-09 09:56:26

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Jimmy B.
Just can't wait to get on the road again.

 
                             Click to see larger views!

[QUOTE=aceinthehole][QUOTE=dsireme]Is this the valve everyone is talking about???  Not sure how well the plastic one works. I used the metal style, but you don't have to mess with the copper tubing. You could just buy the screw in hose barbs, and use a little teflon tape to seal the threads. [/QUOTE] Adams' Apple2009-06-09 09:58:32

[QUOTE=dsireme]And Joel, what is this tying hoses together, is the like having your tubes tied??? [/QUOTE]

Well...I wouldn't know...my tubes have never been tied...(that I'm aware of...)

What I am referring to is removing the hoses from the heater core, and installing a short piece of metal tubing to connect the two hoses(from the engine) together. It's like taking two hoses to make one...does that help?
Adams' Apple2009-06-09 10:04:00

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

[QUOTE=Adams' Apple] [QUOTE=dsireme]And Joel, what is this tying hoses together, is the like having your tubes tied??? [/QUOTE]

Well...I wouldn't know...my tubes have never been tied...(that I'm aware of...)

What I am referring to is removing the hoses from the heater core, and installing a short piece of metal tubing to connect the two hoses(from the engine) together. It's like taking two hoses to make one...does that help?
[/QUOTE]

[QUOTE=dsireme] Screw in what?(no comment some of you) I have no clue what that is.[/QUOTE]

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Jimmy B.
Just can't wait to get on the road again.

 
                             Click to see larger views!

The piece I used 20 years ago on my Grand Prix was a U-shaped metal tube.  I'll check out the plumbing area of my local Home Depot and see if I can find anything with two different sizes on either end.

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I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!

If you are going to install only one valve you would install a valve in THIS hose where Im pointing.   If you are going to install two valves, the second one would go on the hose which exits the heater core and goes to the water pump HERE.  If you prefer the valves not to show, they can be installed under the car but still in reach without lifting the car LIKE THIS.  These valves are under the car near the heater core inlets where the hoses turn upward to connect to the core.  The valves you see are the NAPA valves.

My heater core has been bypassed by  hose, the bad part is I don't see where the hoses should hook to the heater core. I LIKE a heater in the winter even here in the south.So, I'm having vacuum line problems with my A/C-the A/C  blows nice and cold below the dash but the vacuum lines that operate the ducts are not there so I'll be tracing and replacing them but at the same time I would really like to know where my heater core is! On most GMs it's in the fiberglass box that is by the A/C dryer, but I see no tubes sticking out there...help anyone?

How come mo one makes sure the valve installed into the car is working. The valve installed is operated by vacum from a vacum switch behind the passenger dash panel and is acuated by the temp selector being moved to the off position. (1977) not shure the different year changes but should be similiar. If operation is correct the water is shutoff. then as to Joels point you would want to add the valve on the return side to stop the convection off heat from that hose. which if we were to install another vacum valve on this hose and tee it off, it should block all heat and work automaticly no mechanical valvesneeded?

[QUOTE=mysticstriper]My heater core has been bypassed by  hose, the bad part is I don't see where the hoses should hook to the heater core. I LIKE a heater in the winter even here in the south.So, I'm having vacuum line problems with my A/C-the A/C  blows nice and cold below the dash but the vacuum lines that operate the ducts are not there so I'll be tracing and replacing them but at the same time I would really like to know where my heater core is! On most GMs it's in the fiberglass box that is by the A/C dryer, but I see no tubes sticking out there...help anyone?[/QUOTE] The tubes are on the bottom, need to get under the car to get to them.

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Lifetime Member #116
Dave's '82

   

I installed two valves and it helped alot but I still get some warm air in the corkpit with the heater off, cause with the ign switch on the fan motor still runs with the fan switch off, has something to do with the Astro ventalation set up ,so now what I do during the summer is close the valves and disconect the fan ground lead so that the fan doesn't run, I don't run my AC cause it throws compressor oil, even when I replaced the seal, long ago I read somewhere here that you could disconnect a brown wirer I believe at the AC blower motor cut out relay or blower motor risistor I can't remember or find it again, but it kills the  the low speed on the blower motor but it still allows med and high to work, I'd post photos of my valve set up but don't have a clue on how to do it anips2009-06-23 18:50:19

Just for info sake I went to napa this morning to get my brake rotors (another project) the parts guy found me avacum of control vale that is for 3/4 in hose. so I had him order it for me and I will install and see how it works.

I totally agree with Joel. If you want to shut off heat, ya might as well do it completly with bypass connector. With my 71 its easy, as the heater hoses are right behind the side grill. You can get hose reducers, 5/8" to 3/4" at any auto store. I know because I order them 2 doz. at a time. As far as vacuum control valves,  iffin they worked you wouldn't have this problem in the first place. With manual valves your only gonna shut off part of the heat, not all of it as previously mentioned.

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Click on images for Before and After pics!