Barry Wolk
11-22-2025, 07:40 AM
I don't believe that any of the air cleaner heat diverter valves are working on any of our cars. I've never seen one that did. The heat damper is moved by a device called a wax motor, commonly used on cooling system thermostats. They work on the theory that heated wax can create motion under the correct circumstances. It is used on the Mark II air cleaner to use waste heat from the exhaust manifold to act as a warm-up device. It takes two cylinders of heat off the LH manifold and redirect it to the carburetor intake until their is sufficiently warmed that the diverter closes, shutting off the excess heat.
The specifics of this wax motor are unknown, at this time. There are no replacements. Someone had suggested replacing the door spring with hardware store variety springs, but a stronger spring would make matters worse and a weaker spring only adds to the problem. Since this is designed as an aid for extreme cold starting almost none of uses our cars in those temperature I've found a way to permanently disable the device allowing the extra heat to exit the engine without adding constant heat to the intake.
The wax motor has so much force that it needs little mechanical advantage to work. Without it's function the diverter door id permanently open the a devotee like this should default to permanently open instead of closed. The only way I can see to change the default is to add a virtual doorstop in the form of a metal tube inserted over the pin that creates the movement. Any piece of copper or brass tubing will do. I tried rubber tubing, but it collapsed under heat. I uses a brass nipple for an air fitting, but a copper ferrule for a plastic supply line for your residence will work just fine as long as it's about 5/8" long inserted between the wax motor and the linkage. Once the door is jammed open most of the way use the 5/16" long nut to finish adjusting it completely and properly closed. If a supply of wax motors becomes available the "fix" is easily reversed.
33315
The wax motor is the copper device. It pushes the rod out of it to open the door. When the engine has warmed the diverter opens, allowing cold air to enter the air/fuel mix.
33316
Problem resolved.
33317
The specifics of this wax motor are unknown, at this time. There are no replacements. Someone had suggested replacing the door spring with hardware store variety springs, but a stronger spring would make matters worse and a weaker spring only adds to the problem. Since this is designed as an aid for extreme cold starting almost none of uses our cars in those temperature I've found a way to permanently disable the device allowing the extra heat to exit the engine without adding constant heat to the intake.
The wax motor has so much force that it needs little mechanical advantage to work. Without it's function the diverter door id permanently open the a devotee like this should default to permanently open instead of closed. The only way I can see to change the default is to add a virtual doorstop in the form of a metal tube inserted over the pin that creates the movement. Any piece of copper or brass tubing will do. I tried rubber tubing, but it collapsed under heat. I uses a brass nipple for an air fitting, but a copper ferrule for a plastic supply line for your residence will work just fine as long as it's about 5/8" long inserted between the wax motor and the linkage. Once the door is jammed open most of the way use the 5/16" long nut to finish adjusting it completely and properly closed. If a supply of wax motors becomes available the "fix" is easily reversed.
33315
The wax motor is the copper device. It pushes the rod out of it to open the door. When the engine has warmed the diverter opens, allowing cold air to enter the air/fuel mix.
33316
Problem resolved.
33317