Oil pressure gauge line

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    I am installing the firewall through connections and have a question on the oil pressure gauge line that runs from engine port next to the starter up the firewall and turns into the rubber grommet to the gauge in the dash. Pictures I have taken of various cars have various versions starting with a flexible rubber line transitioning to a copper line before going through the firewall. I have seen both 1/8 and 1/4 inch copper tube, but I believe the connection to the gauge is 1/4. I am wondering if the flexible rubber line portion is actually per original or if they were replaced because of cracking in an original 1/4″ copper line from flexing. The one reference I could find on the PASB search was from 1964 and wasn’t available.

    Thanks for any help. Jim



    What issue was referenced when you did the PASB search?  I’ll see if I have it for you and also get it uploaded.



    Dave, thanks for looking it up. The reference from the report server is below I didn’t know things went back that far but looks like it is in the 1964 Arrow issue #3! – before the PASB’s?

    I forgot to mention mine is a 1935 845, but a ’33 836 is probably relevant if you have it.


    The Arrow – Pressure, Oil Gauge – Tubing Replacement, 1933-
    Subject(s):Motor, Lubrication system
    Model:836, 1236, 1242, 1247
    Publication Title:The Arrow
    Publication Year:1964
    Issue #:3
    Page #:14



    In the early years the newsletters/magazines kind of bounced around.  That article is in an issue of the Arrow.  The Arrows are not currently on line. While looking into this I noticed there are duplicate issues of the PASB for 1964, there were actually only two I believe.



    My 1931 is all copper from end to end. Original? Maybe, who knows? I suspect in that era probably all metal at least.


    The issue whether to have a rubber section in the oil pressure gauge copper line will depend on the type of motor mounts installed in the car. If you have SOLID motor mounts, then a solid line will be OK as the motor does not move relative to the chassis or firewall. This also means that solid exhaust line mounts will be satisfactory.

    On the other hand, if your car has rubber (flexible) motor mounts to reduce vibration like all modern vehicles, then the motor DOES shake relative to the chassis and the rubber tubing section is essential. Copper will quickly work harden and become brittle from flexing. If the engine is moving relative to the firewall, then you do need something to absorb that movement to prevent the copper tube from cracking and leaking. The same is true with the exhaust mounts, which is why all modern cars have a rubber flex piece between the body and exhaust line at every support point.

    Good luck and stay safe during this plague. Herb


    Thanks for the responses. Digging through my boxes – looking for something else – I came across the remains of the rubber flex oil line that was on the car in 1964, probably original. When I inventoried my boxes decades ago I didn’t know what it was and for some reason didn’t record it on my spreadsheet with a description that came up with my key word search. Getting a car with lots of boxes means many parts that you don’t know what they are, I still have a few of those and I will probably post some pictures at some point. Meanwhile I found a flex oil line to bridge between the engine fitting and the copper line going through the firewall at McMaster Carr and have an original gauge set up and working.

    On my ’36 Packard, which has a very flexible 3 point rubber suspension system (Chrysler patent), the oil pressure line is smaller gauge 1/8″ copper line with several spiral turns above the fitting to allow for the flex instead of rubber.


    Thanks again!


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