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Thread: PA-12 Oil Burn Rate

  1. #1

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    PA-12 Oil Burn Rate

    I am buying a P-12...It's been sitting 6 years..in a hangar. Mid time 0-290D-2, 135hp. I have flown it 2 hours and plan on putting another few hours on it prior to closing.

    Compressions are mid 70's...what should the oil burn rate be? Anything else I should be concerned about regarding an engine sitting that long?

    Any advise would be appreciated!

  2. #2
    aviationinfo's Avatar
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    Was the engine pickled prior to the long period of disuse? I don't know about burn rates on O-290s.

    I'd be real concerned about corrosion on the cam, which unfortunately may not show up right away. My understanding is that the only way you can tell is to pull a cylinder or two; most owners aren't going to want you to do that. Can you maximize the number of hours flown on it prior to the sale? Or else, budget for an overhaul and hopefully not need the money. As you may know the O-290 is now unsupported by Lycoming and although you can find parts for it, you need to be proactive.

    The 12 is a great airplane and the O-290 is a fine engine but if it starts making metal you'll be faced with a potential decision to try to overhaul it or just get an STC to install a 320.
    Last edited by aviationinfo; 06-13-2012 at 11:03 AM.

  3. #3

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    The allowable limit for oil consumption question is answered in Lycoming literature.
    The following formula is used to calculate the maximum allowable oil consumption limits for all Lycoming aircraft engines.
    1. FIXED WING



    0.006 x BHP x 4 7.4 = Qt./Hr.
    In the case of your 135hp engine the manufacturer's limit is .44 qts per hour.

    How many years since major overhaul? How was it operated prior to the long nap? I'd want a peek at the cam. In doing so I'd get a good look at one or two cylinders. Without a look-see I'd value the engine as run out. But that's just me. Others approach airplane purchases differently.

  4. #4

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    I've got a J5 w/ the O-290 D2. Bought it w/ 35 hours on a fresh re-build, Up to 125 hours now. While bringing it home we ran it hard due to the low time, and found that this particular engine would send anything over 6 qts. out the breather. Once it hit 6 qts, took about a qt every 6-7 hours to bring it back up to 6. Two annuals have averaged all compressions in the 76-78 range. FYI we burned 8.5 gph running @ 2300-2400 rpm (leaned), and I burn about 6.6 gph piddling around @ 700' and 1900 rpm. Engine has been purring right along w/ no issues. Just some reference info FYI.

  5. #5
    mvivion's Avatar
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    As has been noted, if that engine want properly preserved prior to being stored (ieickled) I would just about guarantee you'll be buying a cam and followers or another engine.

    Ive been around a couple of these owned by friends. One went almost two years and 200hours before the cam started coming apart. The other started to make metal 100 or so hours after he bought it.

    Both these guys planned on the potential, and factored in the cost at purchase. With a 290 , though, a cam may be hard to come by.

    Id plan on having tO tear that engine down. Might not happen for a while, but....

    MTV

  6. #6
    sjohnson's Avatar
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    About 10 years ago, I was faced with overhauling an O-290. Cylinders are hard to get. It was about the same total cost to sell the O-290 and buy a much newer low-time O320 + STC. The weight gain was about 15 lbs, which was easily recovered using lightweight accessories. Besides being easier to buy parts, there is no substitute for horsepower.

  7. #7
    Steve Pierce's Avatar
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    O-290s are bad about blowing oil out the breather tube as well. I'd fly it and llok at the gear leg and belly.
    Steve Pierce

    "When everything seems to be going against you, remember that the airplane takes off against the wind, not with it."
    Henry Ford

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    One data point. Got an O290G/D 130hp in the Spezio. Put 6qt in last oil change and in 9 hours it's used less than 1/2 qt.

    I agree about overhaul. Mine has 130 SMOH. Unless I find and put cylinders etc. on the shelf, I plan on an O320.

  9. #9

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    Well it seems I am in the market for a O-320. Any suggestions on where I may find one, please feel free to let me know.

    There goes my other daughters college tuition

  10. #10
    N5126H's Avatar
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    Must be going to a state school

    Quote Originally Posted by SamP45 View Post
    Well it seems I am in the market for a O-320. Any suggestions on where I may find one, please feel free to let me know.

    There goes my other daughters college tuition

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    I'm not to sure that its a sure sign the cam will go if a engine is not operated. I not only look for the amount of oil thats being consumed but also what it looks like if oil is getting dark after 10 hours or so. Could be the ring blow-by but I remove the valve covers if there is dark black coked exhaust valves then you have exhaust gases leaking through the valve guides the those valves start sticking/lagging small amounts in the valve train (not even noticeable when starting up like loping when they get real bad ) and then the cam starts hitting the lifter body instead of a nice smooth travel and the combustion gases pressurize the case and you get blow-by but yes still not good to not run a engine and let it sit
    Steve C

  12. #12

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    I don't know about that? Best to pull cylinder/'s and look at cam. Send oil in to see if it's making metal.

  13. #13
    aviationinfo's Avatar
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    I think if you let your plane sit for six years then it should be pretty much expected that a potential buyer is going to want to pull a cylinder or two. This is a problem these days especially; sellers stopped flying when fuel got expensive then sat for years while they came to grips with selling.

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