59 Pressure Vessel

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This topic contains 2 replies, has 2 voices, and was last updated by  Uwe & Ulrike 5 months, 1 week ago.

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    Uwe & Ulrike

    Dear All
    During the winter season I thought it may be a good idea to renew the underbody sealant of our 59 Montclair. While working on the left wheel case I dismounted a tank that was connected via another vessel near the firewall to the underpressure outlet of the carburetor. So I assumed both tanks belong to the underpressure system. Surprisingly red oil ran out! Has someone an explanation for that? What is the oil good for? Shall I refill it? Type? Ammount?
    Appreciate any information!
    Greetings from abroad, Uwe

    • This topic was modified 5 months, 2 weeks ago by  Uwe & Ulrike.


    The “Pressure Vessel” is truly the Vacuum reserve tank. I have a few 59 Mercurys and have never encountered oil in a vacuum tank. The oil being red might indicate transmission oil, however 59 mercury should not have a vacuum diaphragm on the transmission. If the vehicle was equipped with the rare option of a “Multiluber” there could be a leaking diaphragm at that pump that possibly entered the system. Drain it out and drive it. A little oil down the intake is good for valve guides.


    Uwe & Ulrike

    Thank you for your information! Your are right, it is a vacuum reserve tank. The “oil” is just the condensate of fuel and oil dust decanted over the last 60 years …

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