Is heater core part of coolant bypass in Chevy 350.


Asked by Jan 29, 2015 at 05:55 PM about the Chevrolet C/K 10

Question type: Car Customization

I have a new (to me) 1965 Chevy C10 pickup that seems to be cobbled together. The
heater core just sprung a leak, and in disassembly I discovered that the heat control lever
Bowden cable doesn't connect to anything, there is no diverter flap or heater control
valve. It would be easiest for me to add a heater control valve that just limits or shuts off
the coolant going through the heater core.

I'm unsure if this is safe for the engine - it occurred to me that the heater core (not having
a valve) might be an essential part of the coolant bypass.

The engine isn't what I expected, the stamped letters on the front passenger side of the
block are "CKL" which I think means it is a 1973 350 from Impala, L-65. But I think is is
coupled to a 2-speed Powerglide. Sheesh.

Anyway, considering this engine, is it safe to interrupt the hoses going to the heater core?


11 Answers

Bob Beaman

You could just hook the 2 heater hoses together. It will require and adapter and a couple of clamps or you can loop the hose together at the engine thus requiring just 2 hose clamps. Won't hurt a thing, but you won't have any heat.


Thanks, Bob. I do have a new heater core, though, and what I'm hoping to do is to be able to control the heat. I just don't know if it's safe for the engine to do it by adding a shutoff valve.

Bob Beaman

Pretty sure they used heater water control valves many moons ago in the SB Chevy. Now you got me curious so I will do some investigating.


Thanks Bob!


These are the two hoses that go to the heater core. Pointing with finger and thumb.

1 out of 1 people think this is helpful.
Bob Beaman

I think the really old small blocks had a short bypass hose from the water pump to the intake manifold and they used a heater water control valve. According to a Hot Rod Mag. article I skimmed the newer small blocks are internally bypassed.

Bob Beaman
30,365 neccesary/ article is mainly about big blocks, but the small block is mentioned early in the article.


Bob, I see where they mention it, does make it sound like the bypass is internal, so I should be able to put the valve inline with the heater hoses. Should I feel confident regarding this?

Bob Beaman

I would feel confident, but it is not my money or truck. If it were me I would try it thinking it is 95% going to work just fine. Just keep an eye on the temp gauge when you first drive it. I'm in for 95%, but I am just a guy on the internet from Kansas that knows a little about cars. Let me know how it goes.

1 out of 1 people think this is helpful.
Best Answer

Bob, I put it all together and just did a test drive with the heater valve "off" and the engine, based on the temp gauge, seemed to warm up as normal, no spiking. Seems like it's fine! Thanks again.

1 out of 1 people think this is helpful.
Bob Beaman

Glad it worked out for you!

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