Leaking Heater Control Valve fix
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Joined: Oct 2013
Posts: 73
Likes: 0
From: Atascadero CA
Leaking Heater Control Valve fix
Hi everyone, newly registered to the forums, but I have been lurking a long time and have found a lot of really helpful knowledge on this forum as I make my way into the world of Corvettes.
I thought instead of just asking a bunch of questions for my first post (don't worry, they're coming) I would try to contribute something back. I have seen a lot of threads about leaking heater control valves, especially on the 85-87 C4s. I recently had the same problem and was rather upset to find out that the stock manifold and valve was well over $150 if it was in stock. This is not a terribly hard fix, but it might save someone a few bucks!
So here's what I ended up using for my 1985. Found this valve at a local Napa for $15 and it works almost as a direct replacement for the stock set up, and still allows water to circulate to the TB when the heater valve is closed. The valve (pn: 660-1293), 3' of 5/8" heater hose, 3' of 3/4" heater hose and 8 clamps were all it took! I replaced the short hoses that were attached at the firewall and the short section going up to the throttle body with new, longer hoses. Existing vacuum line pops right on! No more leaking, and a toasty warm, happy corvette owner.
and what i think is going on with this valve
Hope this helps someone!
I thought instead of just asking a bunch of questions for my first post (don't worry, they're coming) I would try to contribute something back. I have seen a lot of threads about leaking heater control valves, especially on the 85-87 C4s. I recently had the same problem and was rather upset to find out that the stock manifold and valve was well over $150 if it was in stock. This is not a terribly hard fix, but it might save someone a few bucks!
So here's what I ended up using for my 1985. Found this valve at a local Napa for $15 and it works almost as a direct replacement for the stock set up, and still allows water to circulate to the TB when the heater valve is closed. The valve (pn: 660-1293), 3' of 5/8" heater hose, 3' of 3/4" heater hose and 8 clamps were all it took! I replaced the short hoses that were attached at the firewall and the short section going up to the throttle body with new, longer hoses. Existing vacuum line pops right on! No more leaking, and a toasty warm, happy corvette owner.
and what i think is going on with this valve
Hope this helps someone!
Heel & Toe
Joined: Aug 2025
Posts: 18
Likes: 4
From: Calgary Alberta
love this post thankyou, so you just replaced your hardlines with rubber hoses and used this valve in its place?
id like to find a way to retrofit this in to my hardlines maybe even with cutting my old lines and flaring them for rubber hoses
id like to find a way to retrofit this in to my hardlines maybe even with cutting my old lines and flaring them for rubber hoses
