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1971 Mark III Headlight Door Issues

Hi Bill -

Need suggestions, have a customer that just bought a 39k car from a estate sale, problem is headlight doors creep up after car is shut off. Have checked vacuum lines and supply tank - any ideas where to go next? Any help would be nice. Customer did say they will come up while driving.




Hi Don,

As we have written on previous posts the headlamp covers are operated by vacuum as you already know. A built in safety system causes the covers to fail in the open position and with larger leaks the covers will open sooner. Therefore the only way to find the leaks is to inspect ALL of the areas that vacuum is routed to for the vacuum headlamp control circuit. The best way and the most sensible method is with the use of the correct vacuum diagram a hand vacuum pump and some knowledge of how the system operates. Our experience is that a leak or any combination of several leaks can be found at any components that the vacuum for the covers and controls is sent to. These are.... the two Vacuum Motors at the covers, Reservoir, Vacuum Check Valve, Headlamp Switch, Manual Valve (near reservoir) and any Hose or Junction in the circuit. All of the above necessary components must be installed correctly and all are candidates for failures.