Low oil pressure

April 24, 2008 by Steven W. Ells, Associate Editor

I’ve been leveraging my airframe and powerplant education lately on a 1960 Piper Comanche 180. One of the benefit packages that come with an A&P certificate is the delusion that I will come out ahead by buying an old airframe and sinking time and money into it. My rationalization works like this: There are only 230,000 light aircraft in the United States, which has a population of nearly 300 million souls. Someday people are going to realize that light aircraft are rare and scarce and that’s when I’m going to be in position to cash in. At the present time, I’m still in the cash-out phase of this equation.

Yesterday I drove out to my favorite engine shop to get a new oil pressure check ball. When I took mine out to inspect it I found a little  corrosion and a wear spot. I pulled it to look it over, but mainly to put a couple of washers under the relief valve spring to up the oil pressure. Lycoming says my O-360 should have an oil pressure of 75 to 85 psi at cruise; mine is 62. The PA-24 owner’s manual says the green arc is from 65 to 85 psi. I put in a new spring and one washer. I’ll fly it today and report back on the progress.

3 Responses to “Low oil pressure”

  1. Paul Richfield Says:

    Don’t forget to recogitate the Fetzer valve. You’ll need some ball bearings and a 100 feet of flight line.

  2. Steve Ells Says:

    My fix jacked the OP up to 71 PSI in cruise. Unfortunately it seems to have accelerated to minor oil leak I have and has completely kazoogled the JPI oil temp probe. Oy!!

  3. J Ritchie Says:

    Well now that’s your into it, might as well overhaul the engine to fix all the gasket leaks.
    When you pull the engine, you find the firewall could use replacing.
    Then you notice the boot cowl has a big hidden crack (replace it).
    Might as well repaint the whole airplane as the new boot cowl paint won’t match.
    Paint stripping reveals extensive sheel metal work required on wings and fuselage.
    When wing sheet metal is removed, wing spar has deep corrosion…

    Ahhh, the joys of old airplane ownership!
    At least your A&P labor is free :-)

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