C-150 Water Contamination ?

Discussion in 'Maintenance Bay' started by bobkiksass, Mar 24, 2013.

  1. bobkiksass

    bobkiksass Pre-Flight

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    Hi,

    My cessna 150 ran rough for about 15 seconds during the last 3 times I flew it. What would happen is at wide open throttle randomly the engine would vibrate, sound a little off, loose maybe 10-15% power. Then after about 10-15 seconds it would smooth out, power would restore and run like normal.This happened once during each flight of about an hour.

    Also, at initial startup the motor would sometimes sound a little off like its skipping a beat. But after warming up maybe 3 minutes would sound just fine.

    My mechanic did oil analysis and they found slightly high aluminum at the last oil change, and suggested to watch for morning sickness or sticky valves. After the motor ran rough for a moment again yesterday, we decided to pull the plugs tested compression and dumped the carb bowl. My plugs were not bad, compression was all above 78/80. He seemed to rule out the valves, or dirty plugs. There was not a bunch of crap in the carb bowl.

    He seemed to think the motor could of sucked some water thru the system, or could be a bit of carb ice, or the mags could need work. So he showed me a trick to tip the plane on its tail and shake it, then sump the tanks. I was amazed one wing I pulled out maybe a 1/4 of the strainer full of water about 10-12 times. Each time I would let it settle shake the plane on its tail, then sump it. This was after I had just flown it this morning after sumping it and experienced the bit of roughness. So there was definiteley water in the tanks, since I pulled that much out after.

    after doing some research about sumping these tanks I found http://www.sumpthis.com/cessna150andcessna152tanktest/cessna150tanktestimages1024x768.htm . These tests show the sumps are incredibly bad at pulling water from its lowest point. The author alleges that there could be many unsolved accidents with motor quitting that are caused by this design flaw. It makes me think my tank could still have substantial water in it.

    What practice are you guys using to sump your 150 tanks? My mechanic suggested sumping it aggressively, do it initially during preflight, run up the motor for 3 minutes.... kill the motor, do it again..... then do it before and after each time fueling and at the end of each flight. And tip the plane on the tail and shake it during each time. I have a belly drain too. I am thinking I should be sucking more than just one strainer thru to really test it.

    The only other thing the guy thought could be causing the occasional roughness was my mags, which are 10 years old since new, havnt been redone and have about 325 hrs on them. He suggests redoing them.

    Has anyone else dealt with water contamination in fuel in C-150 and what are your ways of insuring no contaminants ?
     
  2. FORANE

    FORANE Cleared for Takeoff

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    Some time back I bought a 150 to train my fiance. We did not hangar it and it always had water in its tanks.
    http://www.generalaviationnews.com/...on-water-contamination-and-cessna-fuel-tanks/

    My composite plane absolutely does not have that problem - I could go for a year before the strainer has 2 teaspoons of water in it. The 150 is just prone to it.

    Mags I believe are 500 hour items, but 10 years is long. Has the timing started to advance? Getting harder to start? If so, I would look at the mags. If not, I would lean toward that carb ice possibility as that plane is associated with it.
     
  3. bnt83

    bnt83 Final Approach

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    I wonder how many folks have seen that website.
     
  4. N801BH

    N801BH Touchdown! Greaser!

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    That is quite the detailed report... Congrats on the author..:yes:
     
  5. dell30rb

    dell30rb Final Approach

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    Are the 152 tanks the same design? This is not the first time I have heard of this sumping issue.

    Shake yo tailfeathers before sumping and inspect/replace fuel caps, seals.
     
  6. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    If you're finding water in your 150 tanks, you better be looking at the fuel caps. Despite wive's tales of condensation in partially filled tanks, you really aren't going to get appreciable water from that. Leaky caps however, can make things wet in a hurry.
     
  7. d.grimm

    d.grimm Pre-takeoff checklist

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    There is a STC'd fuel drain that goes in the belly under the fuel selector.
    There is already a plug there, replace it with quick drain,
    Fill out 337, all done. Wouldn't fly a 150/152 without it.
    Dave
     
  8. bnt83

    bnt83 Final Approach

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    Agreed, they all should have those.
     
  9. somorris

    somorris Pattern Altitude

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    Another thing -- even though not the sequence in the POH, sump both wing tanks before you pull the carb drain. It will help keep any water in the wing tanks from being pulled from the wing into the fuel line and maybe not drained when you fill a cup from the carb drain.

    I have a C-150 that had a real problem with water. I replaced the fuel caps, but the problem continued. The filler necks have a gasket inside the tank and then on top of the tank (2 gaskets on each filler neck). When I replaced the gaskets, the problem stopped. Our C-150 was tied down outside, but no water after the new gaskets.
     
  10. flyingmoose

    flyingmoose Pattern Altitude

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    If you found water in your tanks then I would say that would be your problem. If pulling the mags would make you feel better than have at it, shouldn't take that long to "Have a look!" But since you found a significant amount of water, I think you have your culprit. Nice article you found.
     
  11. Dan Thomas

    Dan Thomas En-Route

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    That's what I'd look at, too. Those cork gaskets are around $30 apiece from Cessna, though. Ouch. The flanges also get warped from overtightening the screws, and they need straightening or even the new gaskets won't work. And there are two thickness of gaskets, 1/32" and 1/16". Get the thick ones.

    And use some Fuel Lube or other sealer on the screws. They go directly into the tank and water seeps down around them.

    I'd like to know what attitude the OP's airplane is sitting in when tied down. The 150 tends to sit pretty level even with the strut inflated a bit, and if the strut is nearly flat or the airplane is facing down hill a bit whenever he drains the sumps, the water won't come out. Other than that, those tanks aren't all that bad for retaining water; far less so than Cessna's bladder tanks, which get wrinkles in the bottom and trap water. The OP should not only lower the tail, but grab a strut and rock the airplane side-to-side, too.

    When lowering the tail, don't push down on the stabilizer. You induce cracks and dents in the forward stab spar and crush the nose ribs. Push down on the dorsal fin. That stab spar is no more than the two bends where the top skin folds down and then back to become the bottom skin. Really thin stuff.

    Dan
     
    Last edited: Mar 24, 2013
  12. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Final Approach PoA Supporter

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  13. Dan Thomas

    Dan Thomas En-Route

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  14. Tom-D

    Tom-D Taxi to Parking

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    buy 2, 12 oz cans of this stuff http://www.drygas.com and pour 1 can in each tank, sumping will not get all the water out, dry gas will.

    then change the fuel filler cap's gaskets and you should be OK.
     
  15. bnt83

    bnt83 Final Approach

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    Because these are approved for use in aircraft...



    Dry gas is an alcohol-based additive used in automobiles to prevent any water in the fuel from freezing, or to restore combustive power to gasoline spoiled by water. The name Drygas is actually a brand name, owned by Cristy. It is a liquid that is added in to the fuel tank, that absorbs the water and keeps it in solution.[citation needed] Some brands contain methanol and some contain isopropyl alcohol.[1]
     
  16. Tom-D

    Tom-D Taxi to Parking

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    Water ain't approved either..

    the 0-200 will not be harmed with a dose of alcohol at 12 oz to 12 gallons, many Alaskan pilots use all summer in every new load of fuel.