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1969 Mark III Vacuum And Acceleration Issues

I have air release under my dashboard, possibly preventing the vacuum system from allowing my headlight covers to close. Do I need to remove the dashboard to get to it or is the air release coming from the engine compartment. I replaced all visible vacuum lines and I suspect the air release under the dashboard is rotted or cracked.
One more question related to acceleration. When the car sits for an extended period of time, I can’t accelerate in 1st gear. The car revs really high like the transmission is shot, however after it warms up a bit, no issues at all. Also, when I accelerate up a hill or at a faster pace then cruising, I get a rattling sound under the car as if something is loose, however nothing is and once the car levels out or I accelerate enough, it’s quiet again. Any thoughts? Any assistance you can provide would be great!
Hello Gerardo –
By air release I think that you mean a vacuum leak and yes a vacuum leak at certain vacuum hoses or vacuum switches will prevent the headlamp doors from closing. I cannot tell you to remove parts to find the leak because finding and repairing the leak may not require any major disassembly at all. If you can hear a vacuum leak under the dash, it may be caused by any number of hoses that has disconnected under the dash as the 69 Mark has several. I would carefully try to locate the culprit by listening to the leak and following the hoses from the headlight switch vacuum section as they lead to and through the firewall to the vacuum motors. The sw. itself may have fallen apart. Let us know what you find.
A transmission that is slipping and allowing the engine to rev up when cold would seem to indicate that the transmission is low on fluid. If it is not low on fluid it may require an overhaul and if that is suspected a visit to a trusted transmission shop may be needed for further diagnoses.
I can’t tell from here what your rattling sound is when accelerating but what you describe could be engine pinging from incorrect ignition timing or low octane fuel. Your Mark is designed to operate on premium high octane fuel.
I do hope that the above helps you to correct these issues that you are currently experiencing. If you need anything further in the way of advice or parts please do not hesitate to contact us.

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