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Thread: Oil Leak caused by chafing

  1. #1
    Senior Member kiwibob's Avatar
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    Default Oil Leak caused by chafing

    I arrived at the hangar this afternoon to find a small (CD size) patch of oil below the aircraft. It took a while to find the cause as I started by assuming that last weeks oil and filter change were responsible.

    Finally, with the telephone help of my friendly engineer, I tracked it the oil return pipe from the cylinder head on the starboard rear cylinder which has been chafing on the plastic cowling. Yes, it seems plastic cuts aluminium - see photos.

    This particular pipe is visible from the oil filler hatch but to see the area where it is chafing requires cowl removal as it's tucked under the cylinder.

    Although the amount leaking was small it clearly had potential to spoil my day on a long flight, especially since I don't generally check the oil while hot between same day flights. I shall in future.

    I'll be looking at replacement/repair today but it needs some way to separate the pipe from the baffle to prevent a recurrence. I also need a good look at the others which will require a little more disassembly.

    This slipped through the last 100 hour/annual in February at 265 hours. It's now 301 hours on the tacho.

    P1070726.jpgP1070725.jpgP1070727.jpg
    Bob Gray, FX-3 #38, ZK-FXC

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    Senior Member cityrancher's Avatar
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    Default Re: Oil Leak caused by chafing

    Thanks for posting this. I will have a close look at mine Monday.

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    Default Re: Oil Leak caused by chafing

    Quote Originally Posted by cityrancher View Post
    Thanks for posting this. I will have a close look at mine Monday.
    Has anyone else experienced small oil leaks with the EX-2 light weight oil cooler lines? My right hand line has leaked since new at the lower elbow tube and b nut. I tried a new line and 822 8D elbow and it still leaks. I then tried conical seals to no avail. I am pretty certain that is the origin because it continues to seep slightly even when the engine is shut down and everything else is dry. It doesn’t seem likely, but I’m beginning to wonder if I could have gotten two lines with bad flares??

    Thanks a bunch,
    Tom R
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    Default Re: Oil Leak caused by chafing

    Quote Originally Posted by Tom R View Post
    Has anyone else experienced small oil leaks with the EX-2 light weight oil cooler lines? My right hand line has leaked since new at the lower elbow tube and b nut. I tried a new line and 822 8D elbow and it still leaks. I then tried conical seals to no avail. I am pretty certain that is the origin because it continues to seep slightly even when the engine is shut down and everything else is dry. It doesn’t seem likely, but I’m beginning to wonder if I could have gotten two lines with bad flares??

    Thanks a bunch,
    Tom R
    Hi Tom, Both of my oil cooler lines are leaking. They are leaking from the oil cooler, not the fittings. The oil runs down the line and gives mine the perception of leaking fitting on the lower joint. I have 15 hours. I am going to take the fittings out of the oil cooler and try some new sealant and see if that will help. Also, my oil pressure was extremely high. I brought that down a little.

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    Default Re: Oil Leak caused by chafing

    Quote Originally Posted by Cody View Post
    Hi Tom, Both of my oil cooler lines are leaking. They are leaking from the oil cooler, not the fittings. The oil runs down the line and gives mine the perception of leaking fitting on the lower joint. I have 15 hours. I am going to take the fittings out of the oil cooler and try some new sealant and see if that will help. Also, my oil pressure was extremely high. I brought that down a little.
    Cody, I will check, but I believe the top fittings are dry. My cooler fittings leaked as well and I used Permatex high temp sealant #59235 and it seemed to work.
    AeroSport Power indicated they set the oil pressure at 80#’s on CC 340’s at 2400 rpm and 180 degrees. Mine is around 70-72#’s which is probably fine. I have been seeing low oil temps, but when I get those higher, I may bump mine up a bit. Thanks for the reply.

  6. #6
    Administrator Pete D's Avatar
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    Default Re: Oil Leak caused by chafing

    When removing and installing fittings into the oil cooler make sure and use a big wrench on the flats on the oil cooler next to the fitting hole. It is usually possible to get the fittings in and out with one wrench but the cooler can be damaged if you don't use a second wrench on the cooler.
    Pete Dougherty
    Customer Support Manager
    Cub Crafters Inc

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    Default Re: Oil Leak caused by chafing

    Quote Originally Posted by Pete D View Post
    When removing and installing fittings into the oil cooler make sure and use a big wrench on the flats on the oil cooler next to the fitting hole. It is usually possible to get the fittings in and out with one wrench but the cooler can be damaged if you don't use a second wrench on the cooler.
    Good advice Pete. Tom R

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