Thermal spring broken

The flap and counter weight moves freely. I do have the little spring but the thermal one is broke. Is this going to rattle? If so, it’s going to get some repair. Do you have to cut the flap and shaft to get it out? 440 truck manifold. Thanks

grind off the weld on the flap

Why not replace the thermal spring.

If you decide to keep your heat riser valve working, then for proper operation you need the thermostatic spring to be working properly. The purpose of the spring is to increase the resistance to opening while cold, allowing the choke to heat up and then open. Then when warm the spring lessens its tension to close the valve allowing a more direct exit. Rattling- as an old Mopar mechanic, the trick we used to eliminate the rattle had to do with the valve stop. The valve in its normal stop at rest is "over center". The rattling mainly occurs as the butterfly passes the center position on its way to full open. The trick is in the stop. The stop and it's insulating cover are normally "bent" at an angle, about 45*. The trick is to reset this angle so that the valve no longer goes "over center" at rest. Remove the insulator from the stop and straighten the remaining tab. Add a second straightened tab to reinforce it and install the insulator. Upon re-assembly you will notice that the valve no longer goes "over center" but is about "centered". Rattle cured. The only replacement thermostatic spring I have seen is in a kit for a Hemi at $150+. If you find a more reasonably priced one, let us know.

Dont know if it is to spec, but...


1933-1969 Plymouth Dodge Desoto Chrysler Exhaust Heat Riser Thermostat Spring | eBay