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Thread: C-85 Oil pump loses prime experiences?

  1. #11
    Hi guys,

    Tip from an old-timer......remove the oil pressure relief valve....the big bronze nut, pull spring and piston, check piston for wear, replace or polish if worn, squirt in oil, rotate prop, repeat, reassemble, start engine. That was my once a year ritual when I returned from europe to fly for the summer. No heavy lifting, no special oil can connections or other B.S..

    Old & Bold, c140ace@msn.com

  2. #12

    Join Date
    Aug 2012
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    1
    had same problem on new overhaul - you can overfill crankcase with oil about 8 quarts drain excess before starting and it will prime pump,had to do on erocoupe,no way to get tail high enough -found out to fix needed new accessory case,there was to much clearence on oil pump housing-new cases are available for -12,if you have -8, there is place in oklahoma that can overhaul them

  3. #13
    JimRice85's Avatar
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    Jul 2011
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    In a house with my laptop.....somewhere in Collierville, TN
    Posts
    185
    Heavy lifting? What plane with a C-85 is heavy? Maybe in my 35+ years of flying Cubs and other small Continental powered airplane I didn't learn much, but I'll be flying while y'all are still gathering tools. Of course I learned the lift the tail trick from real old timers from the 30s and 40s.
    Jim Rice
    Wolf River Airport (54M)
    Collierville, TN

    N4WJ 1994 Van's RV-4 (Flying)
    N3368K 1946 Globe GC-1B Swift (Flying)--For Sale
    N7155H 1946 Piper J-3C Cub (Flying)

  4. #14
    Richard Warner's Avatar
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    Aug 2011
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    Covington, LA
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    83
    I agree with Jim. The Cub's tail is so light, you'd have to be a 90 lb. weakling to find lifting it difficult. The Champ is heavier on the tail tough, but still can be lifted by a 120 lb. weakling. I had the oil pressure problem with both my Cub and Champ, both with 65 Continentals. I completely overhauled the one in the Cub with all new oil pump componenets and that cured the problem unless it sat for a couple of months. The Champ never did quit losing pressure after it had sat for even a week. I put a C-85 in the Champ and that cured the problem. I used to use an oil squirt can and squirt oil in the pump where the oil temp bulb went until an old time mechanic told me about the tail lift deal. I'm a couple of inches over 6' tall, so have never needed a rope to pull the tail back down. This method really worked everytime I used it and I didn't drool oil on the back of the engine using a squirt can. Try it, you'll like it. Make sure the prop is horizontal like someone else mentioned.
    Last edited by Richard Warner; 09-02-2012 at 12:27 PM. Reason: spelling of a word.

  5. #15

    Join Date
    Nov 2011
    Location
    Minnetonka MN
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    142
    I now have oil pressure.

    IDAH (Ian) (and some others too) had the correct analysis. Earlier I had pressurized the galleries to 20 psi oil P gage indication w a small hydraulic pump for about 1 hour. No pressure on startup.

    I then removed the filter & pumped in a couple of oil can squirts using a 6 inch piece of 1/4 " ID beer hose, pushing it into the kidney shaped slot at least 3 inches so oil did not run out. Got oil pressure right away on reassembly.

    Analysis - The anti-drainback valve on the filter prevents any flow from the gage line or even the galleries from reaching the oil pump gears.

    I didn't want to remove the oil temp sensor as it looks like that has been tried a lot of times previously (different engine) by someone & a pliars/vise grip.

    That must be why a few mechanics assemble new pumps with grease, rather than just oil. Better to get an initial seal. In my case, I probably flushed out the assembly grease when I first ran the engine last spring.

    Thanks guys!

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