Results 1 to 21 of 21

Thread: Mystery O-320 oil leak - spray hitting front right cowling, oil streak from front latch

  1. #1

    Join Date
    Jan 2013
    Location
    Hudson, MA
    Posts
    100
    Post Thanks / Like

    Mystery O-320 oil leak - spray hitting front right cowling, oil streak from front latch

    After each flight I notice a streak of oil running down the front right cowl latch. When I open the cowl, I don't see an obvious source, but I can see where oil is misting the front right of the inside of the cowling. I also see a little oil at the front of the oil sump and around the starter and generator. Oil is not gushing out and it is not collecting at the lower cowl. Could that be a crankshaft seal?

    The plane just came out of a long annual where the carb, oil cooler, engine mount, air filter and most of the hoses were replaced, but most of the replaced parts are behind or below where the oil is collecting. For what it is worth, compression and engine oil analysis were both excellent.

  2. #2

    Join Date
    Jan 2005
    Location
    Fowler, Ks
    Posts
    668
    Post Thanks / Like
    Check the generator mounting bolts that also clamp the engine halves together
    I had a seep there and put some thread/gasket sealer in the hole and sealed that seep
    I still had a very minordrip and FINALY tightened the oil cooler lines and no drips no runs no errors!!!!0


    Sent from my iPhone using SuperCub.Org
    Thanks OzAK thanked for this post

  3. #3

    Join Date
    Apr 2003
    Location
    Clearwater,Fl
    Posts
    2,600
    Post Thanks / Like
    I narrowed my leak down to the number one cylinder through stud I think, same symptoms as yours

  4. #4
    seabeggar69's Avatar
    Join Date
    Nov 2008
    Location
    Ontario
    Posts
    1
    Post Thanks / Like
    Check dipstick gasket.....often overlooked.
    Likes flynlow liked this post

  5. #5

    Join Date
    May 2008
    Location
    Upper Peninsula of Michigan
    Posts
    695
    Post Thanks / Like
    Lol, I did a top overhaul…that fixed mine

  6. #6
    Richgj3's Avatar
    Join Date
    Apr 2005
    Location
    LI,NY
    Posts
    1,221
    Post Thanks / Like
    Probably not this and I hope it is not, but I saw a Lycoming angle valve O-360 in the IA shop today that had a hairline crack in the case forward of the left front cylinder. Look closely. It was hard to see and there was only a bit of oil sprayed around.
    Thanks Jon Stewart thanked for this post
    Likes Scooter7779h liked this post

  7. #7
    jrussl's Avatar
    Join Date
    Jul 2005
    Location
    Madison, WI
    Posts
    664
    Post Thanks / Like
    From your description of the location of the oil, it sure sounds like it could be the front seal. Itís easy to check. Just snake your fingers behind the flywheel and feel for oil on the front seal directly. If itís oily, then replace the seal.


    Sent from my iPad using SuperCub.Org
    Likes hangarmonkey liked this post

  8. #8
    BC12D-4-85's Avatar
    Join Date
    Feb 2016
    Location
    Fairbanks, AK.
    Posts
    3,035
    Post Thanks / Like
    Helps to wash the engine and start over inspecting after a short run. Crank seal, forward lower case halves seam, various crankcase studs, things like that can wear and loosen with time.

    Gary
    Likes boarfish, Richgj3 liked this post

  9. #9
    supercrow's Avatar
    Join Date
    Dec 2008
    Location
    Smith Pond near Millinocket, Me
    Posts
    534
    Post Thanks / Like
    Have seen a couple cracks near the starter mount of 0360's.

  10. #10
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    21,198
    Post Thanks / Like
    I would take it back to the shop that did all the work. They will want to find it and fix it. Oil leaks are funny because they spray all over the inside of the cowl in flight. Look inside the flywheel if you suspect the nose seal.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
    Likes flynlow liked this post

  11. #11

    Join Date
    Jan 2005
    Location
    Fowler, Ks
    Posts
    668
    Post Thanks / Like
    Also , if equipped check the quick drain. Thesecan have a occasional drip


    Sent from my iPhone using SuperCub.Org
    Thanks cubnut thanked for this post

  12. #12
    AkPA/18's Avatar
    Join Date
    Feb 2003
    Location
    Big Lake Ak
    Posts
    746
    Post Thanks / Like
    I have a couple of those leaks on my engine. I just rolled up a couple paper towels to find where the leak was coming from. One is from the case have where it meets the oil sump. The other is behind my oil filter adapter. Now I just fly with a little piece of oil absorbent rolled up underneath the leaks and the cowlings stayed dry. But I am a farmer sometimes.
    http://thrustline.com/

    Takeoffs are optional--Landings are mandatory
    Likes supercrow liked this post

  13. #13
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    21,198
    Post Thanks / Like
    Quote Originally Posted by AkPA/18 View Post
    I have a couple of those leaks on my engine. I just rolled up a couple paper towels to find where the leak was coming from. One is from the case have where it meets the oil sump. The other is behind my oil filter adapter. Now I just fly with a little piece of oil absorbent rolled up underneath the leaks and the cowlings stayed dry. But I am a farmer sometimes.
    But I know when you finally quit flying for the season you will be fixing they leaks. Phone has been quiet, lots to report. Figure there are lots of fish.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  14. #14

    Join Date
    Jan 2005
    Location
    Fowler, Ks
    Posts
    668
    Post Thanks / Like
    Front oil cooler?


    Sent from my iPhone using SuperCub.Org

  15. #15
    Doug Budd's Avatar
    Join Date
    Feb 2015
    Location
    Crawford Nebraska
    Posts
    246
    Post Thanks / Like
    Push rod tube ?


    Sent from my iPhone using SuperCub.Org

  16. #16
    Rick Papp's Avatar
    Join Date
    May 2002
    Location
    Bristolville, Ohio
    Posts
    757
    Post Thanks / Like
    1. Clean engine every nook and cranny. Be thorough.
    2.Allow engine to dry. Blow off any liquids with a shop vac or leaf blower to get completely dry
    3.Puff blue chalk line chalk on any suspected areas of leaks.
    4.Run the engine and usually any leaks will show up by discoloring the chalk.
    Never stay level!!!!!

  17. #17
    Gordon Misch's Avatar
    Join Date
    Dec 2003
    Location
    Toledo, Wa (KTDO)
    Posts
    3,887
    Post Thanks / Like
    Yup, or dye penetrant developing powder - comes in an aerosol can, available at welding supply shops. I once had a leak I couldn't find and finally found it that way after about a half hour ground run. Turned out to be a hairline crack in the case.

    Edit: To clean the engine I use paint thinner with a siphoning blow gun - a cheapo Sears sandblast gun in its prior life. Works great.
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)

  18. #18

    Join Date
    May 2017
    Posts
    1,113
    Post Thanks / Like
    Quote Originally Posted by Rick Papp View Post
    1. Clean engine every nook and cranny. Be thorough.
    2.Allow engine to dry. Blow off any liquids with a shop vac or leaf blower to get completely dry
    3.Puff blue chalk line chalk on any suspected areas of leaks.
    4.Run the engine and usually any leaks will show up by discoloring the chalk.
    I use baby powder, but yeah, same idea.


    Sent from my iPad using Tapatalk

  19. #19

    Join Date
    May 2008
    Location
    Upper Peninsula of Michigan
    Posts
    695
    Post Thanks / Like
    Is there a smoking rivet?

  20. #20

    Join Date
    Jun 2008
    Posts
    5
    Post Thanks / Like
    We had the same issue, turned out to be a defective oil cooler. Replaced it and no leak.

  21. #21
    DR-109's Avatar
    Join Date
    Feb 2010
    Location
    Spring Grove, IL
    Posts
    33
    Post Thanks / Like
    If you have oil spray on the cowl and donít see any other noticeable leaks, it is most likely the valve cover gaskets. If you have the old cork ones replace them with the silicone rubber ones. Part number RG-75906 from Aircraft Spruce. Follow the instructions in the documents and donít over tighten.
    Thanks Willie thanked for this post
    Likes NoFlaps liked this post

Similar Threads

  1. Replies: 8
    Last Post: 05-13-2021, 07:01 AM
  2. PA-18 Cowling latch parts source?
    By supercub in forum Cafe Supercub
    Replies: 9
    Last Post: 03-27-2020, 11:31 PM
  3. Cowling latch P/N 10816
    By FlatSideShovel in forum Tips and Tricks
    Replies: 11
    Last Post: 05-07-2017, 04:22 PM
  4. Mystery oil leak
    By coxcub in forum Super Cub Sick Bay
    Replies: 23
    Last Post: 06-15-2009, 12:29 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •