Sluggy oil leak? Crankseal leak again?

Discussion in 'Maintenance Bay' started by mandm, Nov 29, 2022.

  1. mandm

    mandm Cleared for Takeoff PoA Supporter

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    Just back from some more traveling, yay, I’ll try to post some photos in another post. I put on almost 20 hours this trip, added 1qt of oil before the trip, and another qt before putting on almost 8 hours flying today, some IMC and cold weather today. At the end of flying today, I found some sluggy oil on the top of the cowling. Very sad to see because I just had the crankseal replaced earlier this year. Previously it would only leak on longer flights >3hrs and would lightly spray the windscreen. Would that really fail again, or is this some other issue? Last time though the oil was a light color oil. This spill on the top of the cowling is darker and almost seems soapy or some weird consistency. It did not spray onto the windscreen.

    The oil is getting dirty, last oil change was roughly 3.5 months ago and <40 hours tach so it is time for another oil change. I sent a text to my mechanic, here we go again. :cool:


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  2. Darwin60

    Darwin60 Pre-takeoff checklist

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    Check the oil fill gasket
     
  3. mandm

    mandm Cleared for Takeoff PoA Supporter

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    Thank you, will check it.
     
  4. Domenick

    Domenick Cleared for Takeoff

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    Check the oil fill tube for looseness. Should be safety wired where it enters the crankcase.

    Constant-speed or fixed-pitch prop?
     
  5. Pinecone

    Pinecone Pattern Altitude

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    That was going to be my question.

    If CS how many hours and years since the last service. Look on the back side of the blades for any grease tracks
     
  6. mandm

    mandm Cleared for Takeoff PoA Supporter

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    Constant speed prop, I looked up in the cowling and saw a little oil on the engine case in middle. Didn’t appear to see oil splashing around everywhere. When I add oil I know I did spill some before but the check oil dipstick is a little bit back not at the front.
     
  7. mandm

    mandm Cleared for Takeoff PoA Supporter

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    Constant speed, I didn’t notice anything on the back of the blades, prop mx IIFC was more recently. ~Couple hour hundreds and few years (was flown prob 10-15hrs/yr before I got it, I put on well over 100hrs this yr)
     
  8. Magman

    Magman Cleared for Takeoff

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    My belief is that it’s important to lube the lip of a new seal prior to starting the engine. If it is dry it may wear.

    On TCM engines where the seal is visible I’ve had some moderate success with
    “ painting” the seal externally with some of the auto “ seal softeners “ .
    Note I do not put in the oil. On a Lycoming you have the Support in the way.
     
  9. Dan Thomas

    Dan Thomas Final Approach

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    The stuff on the cowling is an oil/water emulsion. You can see drops of water there, too. You were in IMC, which might be the source of the water. The other source of water/oil mixes is the crankcase itself. If the crankcase breather tube is leaking anywhere it can release that stuff into the cooling plenum, and airflow in some plenums is odd. You have a cowling with a big cooling inlet hole, with a spinner over the middle of that hole, and airflow in the cowl will tend to move forward in the center and carry stuff like oil with it, and it comes out behind the spinner.

    So check the breather tube system Continental often took the crankcase venting off the front of the engine.
     
  10. Rgbeard

    Rgbeard En-Route

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    That looks 110% like the runny nose from a crankcase seal.

    Lots of A&Ps install seals. Not all do it well enough.
     
  11. mandm

    mandm Cleared for Takeoff PoA Supporter

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    Interestingly my mechanic asked me, how many times do I prop cycle during run up. I said 3 times per the manual, he said to only do it 1 time, almost as if doing it 3 times on the regular would cause it to fail. I think with only prop cycling 1 time I thought warm oil wouldn’t be moving through the propeller like it needed to?
     
  12. Rgbeard

    Rgbeard En-Route

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    I agree with you, and I believe most of the CS world does, as well.
     
  13. mondtster

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    I’m guessing he hasn’t had an engine apart with a response like that. Where does he think the oil is going? Lycoming advocates minimal prop cycling with a new engine. If they don’t want you doing it then I don’t know why you’d want to do it with an engine that may be tired as well. But one or three cycles isn’t going to cause a seal to go bad.

    Some engines are chronic leakers. There’s a couple of common reasons for it other than an installation problem, but neither are easily fixed. Hopefully seal replacement doesn’t become a common pattern for you.
     
  14. mandm

    mandm Cleared for Takeoff PoA Supporter

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    I am adding about one quart of oil every 10 tach hours, and oil on the cowling previously would only occur on flights longer than 4 hours, it would not appear on shorter 1-2 hour flights. I had the crank seal fixed before, still waiting for my mechanic to check it and get back to me. It’s winter and I’ll be going into the annual soonish.
     
  15. Dan Thomas

    Dan Thomas Final Approach

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    Cycling the prop won't cause the seal to leak. The oil from the governor goes into the crank nose from the main bearing. The lube system also feeds the main bearing from a couple othe places. Any oil coming off the front of the bearing drains back to the sump via drain hole in the case behind the oil seal.

    Now, if the mechanic really gooped up the seal's OD with sealant, the extra sealant can end up plugging that drain passage and you have major seal leakage. The oil has noplace else to go. This is one reason why RTV is so terrible: it easily plugs passages.

    Cycling the prop flushes it and helps reduce sludging in it.
     
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  16. mondtster

    mondtster En-Route

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    And if there is excess bearing clearance it could lead to excessive oil flow out of the bearing. If the drain isn't clear the oil has to go somewhere...

    The other thing is that there might not be enough clearance between the oil slinger on the crankshaft and the ring in the case that is intended to keep the oil away from the crank seal. Reasons that the clearance becomes inadequate can vary but it occasionally does. If there isn't any clearance, the oil that gets trapped forward of the oil slinger has nowhere to go but out the crank seal.

    Hopefully it is just something simple with the seal installation.
     
  17. Skymac

    Skymac Pre-takeoff checklist

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    Nothing wrong with doing it 3 times or 10. I think people often over due it in the sense of pulling it back and being slow to return it. No need to lug the engine down, just a quick cycle to drop 150 or so does the same and is easier overall on everything.
     
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  18. Daleandee

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    I learned this on auto engines and transmissions i.e. that replacing a seal will not fix the problem if the bearing has too much wear. Not saying that's the case here but something to consider ...
     
  19. mandm

    mandm Cleared for Takeoff PoA Supporter

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    My mechanic said the propeller and crankseal are fine. That it was residual oil and engine weap? Kind of beyond the scope of my understanding so I’m not sure what to think. Given this happens on longer flights I am thinking it’s almost normal to have some oil loss during longer operations especially when adding outside moisture to the equation?
     
  20. Rgbeard

    Rgbeard En-Route

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    I call BS.

    So far, my opinion of your mechanic isn't stellar.
     
  21. Rgbeard

    Rgbeard En-Route

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    Yeah, uhhh, don't let this guy plant THAT in your head. Get a different resource.
     
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  22. Racerx

    Racerx Pattern Altitude

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    Get some dye and a black light and do your own detective work cuz oil should not be showing up on top of the cowl no matter the duration of flight. I've got the kit somewhere if you want to borrow it.
     
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  23. Dan Thomas

    Dan Thomas Final Approach

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    Was the crankcase breather system examined?
     
  24. mandm

    mandm Cleared for Takeoff PoA Supporter

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    Unsure.
     
  25. mandm

    mandm Cleared for Takeoff PoA Supporter

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    That’d be great, I am going to be traveling (not in this plane) and sending the plane into annual this winter, it’s something I could poke more into in the spring time. My mechanic is trying to get me to think about an overhaul, just saying that the last overhaul was so many years ago. I am also questioning what is being said to me by the mechanic as things don’t seem to line up. I definitely was hoping to get more than the 2000hrs TBO to have time to decide if I'm keeping this baby for the long run or not.
     
  26. RyanB

    RyanB Super Administrator Management Council Member PoA Supporter

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    Residual oil from where? Seems most engines that ooze, do so at the top where the case halves come together. That wouldn’t create the problem seen here, unless it was a serious case weap which you should notice. With the amount of oil distributed on top of the cowl, I can’t imagine a situation where you couldn’t trace down a fairly noticeable leak somewhere.

    My recommendation would be to wipe the engine down with mineral spirits and then run it on the ground for 15 minutes at various power settings and cycle the prop a few times. I’m still not sure I buy your mechanic’s analysis.
     
  27. mandm

    mandm Cleared for Takeoff PoA Supporter

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    I remember that I looked through the front openings with a flashlight and I do remember oil present where the case halves came together. I wasn’t sure what to make of that.
     
  28. Pinecone

    Pinecone Pattern Altitude

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    There is a way to seal the top of the engine seam without taking the engine apart.

    There is info over on Beech Talk. You apply a vacuum and run some Loctite 290 over the seam where it is sucked in
     
  29. robin ardoin

    robin ardoin Pre-takeoff checklist PoA Supporter

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    Overhauling based on age alone would definitely cause me to get another opinion. I have a 23yo 182-S with 800hrs since new. Burns VERY little oil, runs great. I just put it in for the first annual since I’ve owned it; I purchased it in September. Borescoping revealed no pitting/corrosion of the cylinders, valves look great. Piston crowns look great. I held an overhaul reserve because a 23 yo engine with sporadic usage living in the northeast US will need an overhaul…..right? I call that engine O/H reserve my panel O/H reserve now;). My broker-A/P-I/A believes in repair/overhaul on proven condition fortunately.
     
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  30. Domenick

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    Sounds like the mechanic is hoping for a payday, and trying to leverage your current issue into an overhaul.
    Good on you for your "spidey-sense." If something feels hinky it usually is.
     
  31. Dan Thomas

    Dan Thomas Final Approach

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    You'd want to be really careful with that. If the loctite ends up hanging off the inside of that seam, it hardens there and breaks off and small bits go through the suction screen and into the pump and will damage it. Besides, the Loctite isn't going to stick to the oily surfaces.

    There are reasons why both Lycoming and Continental have lists of approved sealants. They get to deal with the fallout when an engine craters and investigators find stuff in them that caused the failure.
     
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  32. Racerx

    Racerx Pattern Altitude

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    Pull both upper and lower cowls off. Get the engine and cowls as squeaky clean as you can. Wouldn't be a fun task in the winter. Then put some dye in it and fly it for a bit. The kit is pretty inexpensive but I do have it. I was able to find my leak after 2 trips in the pattern. Any more and it might have been difficult because oil was everywhere. Not a lot of oil, but it was everywhere.

    Overhaul for the sake of overhaul on age alone with no other issues aside from oil coming from somewhere is foolish. No borescope? No oil analysis? No other symptoms?
     
  33. Racerx

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    With oil being on top of the cowl I'd suspect oil to be everywhere and seeing a little on top with a flashlight with the cowl still on wouldn't mean much to me. Could be the source. Might not be.
     
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  34. mandm

    mandm Cleared for Takeoff PoA Supporter

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    Supposedly the last oil change was fine, oil filter was fine, I’m not entirely sure that the oil filter was checked for metal. The oil color changes I cannot remember but less than 10 hours after an oil change. It’s pretty dark now, still under the 50hr recommended time.

    There was no oil analysis, borescope or other symptoms. I can tell my mechanic gets worried when things start to break. Since I’ve had to replace the starter, alternator, fuel pump and crankseal already this year. I don’t think the alternator needed replacing though. But the starter was acting up. Fuel pump started popping a fuse.
     
  35. Magman

    Magman Cleared for Takeoff

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    I have some concerns with doing a re-torque of the fasteners. Is there any history of cylinders being off? If so; I hope they followed the SI explicitly.

    Lycoming engines have issues with the Main Bearing “Saddles” ;particularly if the are not properly torqued. Once the “ fretting” wear develops a re-torque may reduce bearing clearance. I believe some TCM Malibu engines also had this problem. IIRC they want you to put a pull scale on the prop to measure turning effort before and after re-torque. Increase and things come apart.

    Prop o-ring leak?

    I’ve used Pro-seal on some seam leaks with some degree of success.

    Just read your last post. Any possibility the Alternator Belt was changed also? That would require pulling the prop to do so. Always good to replace the o-ring at that time but it doesn’t always happen
     
  36. Pinecone

    Pinecone Pattern Altitude

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    Loctite will not cure in the presence of oxygen. You run some solvent to clean the surfaces.

    IIRC, this technique came from Lycoming.
     
  37. Dan Thomas

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    I have never seen it in any of Lycomings documents. Where is it?

    I have found bits of broken loctite inside stuff. It cures in the presence of metals as well as oxygen.
     
  38. Racerx

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    Let me preface this by saying I'm an idiot. But could the breather tube itself get iced up and or whistle tube clogged?
     
  39. Pinecone

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    Not sure, may have been from a Lycoming engine seminar. A friend did it on his engine and it worked great.
     
  40. mondtster

    mondtster En-Route

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    Yes. You don’t hear many stories about it but it can happen. I’ve never had it happen on an aircraft but I have had it happen a couple of times on other equipment.