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1940 Buick Heater Shut-off Valve Requirement


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As I have stated in my other 1940 Buick threads, I recently purchased a 1940 Buick 46C convertible and I'm trying to better understand and appreciate this new Buick. My latest question pertains to the heater shutoff valve, mounted below the thermostat housing, that connects to a heater hose that feeds the heater/defroster lines at the firewall and then the under front seat heater. As shown in the picture above, my '40 Buick does not have a shutoff valve installed and I believe this is why it gets so freakin hot in the front seat when I take the car for a long drive. I agree with Walt G's comments (from the June 19th thread on the 1940 Buick Special Convertible sedan on NY Craigslist), that the 1940 Buick heaters are very efficient and if you don't control the hot water flow to them, they are like a furnace in the passenger compartment.

Checking other '40 Buick threads, I found the following two pictures that show a flow control/shutoff valve at an outlet, below the thermostat housing, that feeds the two heaters cores. The question I have is do you close off all hot water to the heater cores, when you don't want any heat, or do you leave them open slightly? I believe it is closed completely but need clarification since I have not found any info on this subject.


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Brass replacement shutoff valve for $23.99 on eBay (https://www.ebay.com/itm/NORS-Brass-Manual-Heater-Control-Shut-Off-Valve-Possible-Use-1930s-1940s-Cars/283803158708?hash=item4213fc88b4:g:K2UAAOSwxkpdzeXK)



I wish there was a control valve, that shuts off the hot water to the heaters, like I have on my 1952 Buick Super. Has anyone added a flow control valve similar to what Buick added in 1946, after the war?


Don (2Buicks+1more)

1969 Buick Riviera

1952 Buick Super 4dr

1940 Buick Special Convertible

Based on checking 

Edited by 2Buicks (see edit history)
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I think the idea behind these valves was to close them during the summer months and leave them open during the winter months.  Since I live in a pretty mild climate and don't drive much in cold weather, I have just left the valve closed on my '41.  I have had both the defroster and heater cores out of the car for cosmetic restoration, and they both seemed to be water tight when I tested them with a garden hose, but I figure why tempt fate by constantly running coolant through them when I don't need to.


The valve on my car looks just like the one in the pic posted by Greg (2carb40).






Edited by neil morse (see edit history)
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Agreed--either open or closed. Opening it a little doesn't change anything, it will still eventually heat up to the same temperature as the rest of the cooling system. If you don't want heat, leave it closed. On a cool night when you think you might need some heat, it's no big deal to quickly reach under the hood and open it again.

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