Heater Core Bypass
Le Mans Master
Joined: Aug 2006
Posts: 7,431
Likes: 1,561
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Splice the hoses wherever you like.
One hose is 5/8" and the other is 3/4" so you have to get a reducer. You can cut the hoses and put the reducer anywhere you want or you can put a plug in the manifold and water pump.
Burning Brakes
Joined: Sep 2008
Posts: 805
Likes: 5
From: Naperville Illinois
Just remove the fittings in the pump & manifold and insert plugs. I can't remember where I got them but they are called "heater delete" plugs. Also don't try to pull & twist the hoses off of the core, you will bend the pipes like I did 
. You have to slice them with a razor knife
. You have to slice them with a razor knife
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Burning Brakes
Joined: Sep 2008
Posts: 805
Likes: 5
From: Naperville Illinois
Another project!
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Instructor
Joined: Jul 2011
Posts: 142
Likes: 1
From: Fort White Florida
Safety Car
Joined: May 2008
Posts: 3,755
Likes: 721
From: Lafayette Louisiana
ditto here as well.
Only put 1 valve in on one heater hose, some say use two valves. This plus reflextix (sp?, also at Lowe's) under the carpet everywhere, plus tunnel insulation and bell housing insulation, plus sealing the holes made a world of difference in reducing interior heat.
Good luck and hope this helps.
Good luck and hope this helps.
Drifting
Joined: Oct 2010
Posts: 1,972
Likes: 6
From: Chester Virginia
I went to NAPA first and asked having seen that valve before and my local NAPA which is staffed with less than sterling clerks had no clue over 30 minutes of looking and talking. I like NAPA but the local one is really poor with staff who couldn't find the cash register much less know anything about cars or have a work ethic. I don't go there much anymore.
L.P.
L.P.
Burning Brakes
Joined: Jul 2010
Posts: 755
Likes: 8
From: delco pa
[QUOTE='75;1578335525]Here's what I used, it's actually made for this. I got it from Napa.
do you have teh napa part number for taht valve? it looks like it can be operated with a choke type cable, like teh c1's
have,,, i think i have at least 2 uses for those valves,,,
thanks,
john
do you have teh napa part number for taht valve? it looks like it can be operated with a choke type cable, like teh c1's
have,,, i think i have at least 2 uses for those valves,,,
thanks,
john
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
https://www.napaonline.com/Catalog/C...006348065&An=0
Enter heater valve in the search box on the napa site and you will get hundreds of them to choose from.
Enter heater valve in the search box on the napa site and you will get hundreds of them to choose from.
Last edited by '75; Aug 6, 2011 at 09:50 AM.
Melting Slicks
Joined: Mar 2008
Posts: 2,023
Likes: 6
From: Austin Tx
Another option is to use what modern cars use, vacuum operated bypass valves, such as the one below. That way, the vavle opens or closes when you turn on the heater or AC.
http://shop.advanceautoparts.com/1/1...art-74781.html
http://shop.advanceautoparts.com/1/1...art-74781.html
Last edited by Mashman; Aug 6, 2011 at 10:29 AM.
Thread Starter
Advanced
Joined: Jun 2009
Posts: 66
Likes: 1
From: Akron Ohio
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
Another option is to use what modern cars use, vacuum operated bypass valves, such as the one below. That way, the vavle opens or closes when you turn on the heater or AC.
http://shop.advanceautoparts.com/1/1...art-74781.html
http://shop.advanceautoparts.com/1/1...art-74781.html
this is the best way to do it... I have it and it works great, it is factory for my year 79... All automatic... Got a heater when I want it with out he heat in the summer or day....