Feeling in over my head now

Discussion in 'Maintenance Bay' started by 4RNB, Mar 5, 2021.

  1. 4RNB

    4RNB Pre-takeoff checklist

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    https://www.pilotsofamerica.com/community/threads/smoke.130894/#post-3051900

    Above is the background. Today flying again for the last time with CFI and oil gets on windshield. Mechanic looks at engine, says I need to break it down for overhaul or trade out for zero time ("Through bolt and top of the engine casehalf" is where the leak was). 1974 Cessna 172 M. Engine time is 2000 ish, top end 100-150 hrs. O-320 E2D placed in 1997.

    My current useful load is 777#. I think I will keep the Powerflo exhaust if I keep this engine size. I've been told my options are to overhaul it, mechanic will take off engine, mail out parts, get stuff back, reassemble. 80 hours labor @$95 each He suggested 6 weeks, $20-22K. Exchange engines, 40 hours labor @$95, 10 weeks to get it in from one shop in state, $30K.

    We lost 1/2 quart of fuel (NO NOT FUEL< IT WAS OIL) today. Mechanic initially said plane safe to fly 20 minutes to his airport. CFI said this could be an NTSB report waiting to happen.

    So my questions:
    1. $28K my engine or $34K exchange and why?
    2. Do you know of other shops with in stock exchange engines? I want to fly...
    3. Would you fly this plane to destination 20 min in air?
    4. What about 180 HP engine upgrade to increase useful load? I guess it would be stock exhaust then.

    What else?
    Thanks, I guess.
     
    Last edited: Mar 5, 2021
  2. mondtster

    mondtster En-Route

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    Perhaps it is just a marginal description of the actual problem, but if what you wrote is what the mechanic said I would consider getting a second opinion before proceeding. A picture might help but I’m having a hard time understanding exactly what/where the problem is. Is the case cracked?

    Assuming the engine does need disassembly for repair, it might be best to overhaul or replace the engine given the number of hours on it. That is something you and your trusted mechanic/engine shop will need to determine.

    Would I fly it? Maybe or maybe not. It depends on what is really wrong with it.
     
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  3. TCABM

    TCABM Pattern Altitude

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    New owner and student pilot are a tough combination. I think I’d want to know where the oil is coming from before I made any other decisions.

    For ref, we’ve done two O320s (one in an L, one in an M) and took an N to the 180hp STC in the last couple of months.

    The O320s were both from reputable builders, with new accessories and misc firewall forward stuff. Both were within spitting distance of $30K not including R&R. Neither were two week turn arounds even though both motors were ordered a couple months in advance of the planned swap.

    That doesn’t mean you need an overhaul, just a data point.
     
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  4. guzziguy

    guzziguy Pre-takeoff checklist

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    Concerning your original post:
    You had oil on the windshield, this was fixed, and THEN you lost 1/2 quart of fuel? Is that correct?
     
  5. Bell206

    Bell206 En-Route

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    As mentioned, it seems there's more to this story. Normally you don't correct oil on the windshield with an engine overhaul or replacement unless there is something more substantial like a crack somewhere. And don't quite follow the loss of fuel comment.
     
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  6. 4RNB

    4RNB Pre-takeoff checklist

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    originally only had brief puff of smoke, nothing on windshield.
    Today was 1/2qt OIL, will try and change in original post.
     
  7. 4RNB

    4RNB Pre-takeoff checklist

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    Mechanic said oil came from "Through bolt and top of the engine casehalf"
     
  8. Snowmass

    Snowmass Line Up and Wait

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    If the case is not cracked why not possible sealing at the bolt? What is the engine condition? How many hours since major OH or new?
     
  9. 4RNB

    4RNB Pre-takeoff checklist

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    I do not know the first answer. I am not sure of 2nd question other than what the seller told me. New cylinders about 100-150 hours ago. Bottom end passed visual on frame inspection and is about 2000 hours now. It was a zero time engine placed in 1997. Sorry, I should have put that in my first post.
     
  10. TCABM

    TCABM Pattern Altitude

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    You’re at TBO in hours and way past in years, but again that’s not a reason by itself to OH. What’s your long term plan for this plane? Might be faster/cheaper to get a mid-time motor if you decide replacement is worth it.

    That is all a separate decision from finishing your ticket.
     
  11. mondtster

    mondtster En-Route

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    My answer remains the same, if that is exactly what the mechanic said and told you that you need a new engine that is a poor description at best. Oil from a through bolt or from the case spine with no explanation by the mechanic or a correction plan besides "you need a new engine" is not a thorough enough diagnosis to warrant engine shopping right now.

    I suspect there is a lot more to this story that is being lost for various reasons.
     
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  12. 4RNB

    4RNB Pre-takeoff checklist

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    I spoke to a 2nd mechanic that had two Cessna 172s open in his shop. He suggested it is likely the prop seal, just evolving further.
     
  13. brcase

    brcase Pattern Altitude

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    I think I am a bit familiar with the issue, One of my students had something similar happen on his 150, I seem to recall it only had about 200hrs on the engine. He ended up buying a low time used engine and replacing it and selling the one that he took out. The issue as i understand it (I am not a mechanic) is the case will continue to leak an unacceptable amount of oil. It could be readily fixable but required splitting the case to do so, but the OP needs to have the case split on an engine with 2000 hrs on it, rebuilding or replacing at the same time makes a lot more sense than just repairing it.

    As to repositioning the plane, if it is the issue I think it is, I would have no qualms about a 20 minute flight. But the proper way to do it have the mechanic apply for a ferry permit to do so.

    Brian
    CFIIG/ASEL
     
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  14. Jim Carpenter

    Jim Carpenter Pre-takeoff checklist

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    To the OP, where are you based? High elevation/high density altitude operations would sway the decision heavily toward considering the 180hp upgrade.
     
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  15. Snowmass

    Snowmass Line Up and Wait

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    I believe a prop seal can easily be replaced externally for a minor cost. Replace the seal and the report back.
     
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  16. nrpetersen

    nrpetersen Line Up and Wait

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    If you can identify an oil leak to be at a particular through bolt, have a mechanic check the torque on that bolt. If it makes specified torque, it is probably OK to ferry. If it doesn't, no way would I ferry it.
     
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  17. danhagan

    danhagan Pattern Altitude

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    You need a better mechanic. Prop seal versus engine overhaul is a HUGE difference. When I was a fairly new owner the on field shop tried to tell me I had a case crack and needed a new engine. Sent photos to FletchAIR and Zephyr engines and they indicated "case crease mark" and NOT a crack. I stopped using that shop for all maintenace ...

    I did replace a prop seal on the Tiger I used to own and it was an EXTREMELY inexpensive repair (like less than $175 labor and $35 part back then 8 years ago).
     
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  18. GLDP

    GLDP Pre-Flight

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    How do you know you actually lost 1/2 QT of oil because you saw the oil on the windshield? If you’ve been topping up your oil to the Max in anticipation that you might have a leak the E2D will blow out a couple of quarts quickly and stabilize at around 6 QTS. I never top mine up unless it goes below 6 because I know it’ll just spit it out.
     
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  19. chemgeek

    chemgeek Pattern Altitude

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    My experience is that oil leaks can be vexing to trace. So much air blows around the engine compartment, oil leaks can wind up anywhere and everywhere. I've had hardened pushrod seals splatter oil droplets on the windshield, and a bad sump drain crush gasket slop oil onto the top of the carburetor and dipstick tube base. And I've had a dipstick tube gasket failure put oil everywhere inside the engine baffles. The only way to trace the leak is to meticulously clean the engine compartment before troubleshooting. I would NOT break down an engine for overhaul until I discovered for sure the source of the leakage.
     
  20. unsafervguy

    unsafervguy Pattern Altitude

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    i have never seen a through bolt or a case seam loose 1/2 a quart in a flight. get a second opinion.
     
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  21. Jdm

    Jdm Pre-takeoff checklist

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    Right. One through bolt doesn’t leak that much. I’ve owned a 172M 0320 E2D for over 20 years. It’s probably one of the most simple aviation engines around. I can assure you it’s not that hard to identify an oil leak on a O320. Especially if it’s leaking as much as you say. I’ve also never seen a through bolt that wouldn’t make torque. Seems very unlikely. The whole thing seems odd actually.
    Wash the engine, run, inspect. Repeat until the source is identified. Then confirm with dye penetrate if needed. It’s just not that complicated!
     
  22. Deelee

    Deelee Cleared for Takeoff

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    Yeah this..

    Also, even it there are leaks coming from the case, it doesn't necessarily mean it's time for OH/replace.

    We had an alternator issue just last weekend. A/P fixed it (loose belt and one alternator support bolt missing(!!) ). While he was fixing that, he noticed that there was oil leaking on to the nose gear - ( we had noticed this, too, but were going to have it addressed at annual) - he noticed there were case bolts that were loose. Tightened them up and what do you know... next time I flew, no more oil dripping down the nose gear strut.

    Long story short - just because you have oil leaking, doesn't mean OH. Get a second opinion. These engines leak oil. 1/2 quart... that's a bit much. But try to really trace the source of the leak. May be something as simple as bolts that need to be tightened.
     
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  23. Hiperbiper

    Hiperbiper Line Up and Wait

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    I would think a nose oil seal will put oil outside (on the windshield) but the oil will also be on the front of the cowling...
    A case seam or other engine seal will oil up the inside of the cowl and maybe allow a bit outside thru the top rear of the cowling.
    If you do have a nose seal installed don't watch it being done...it ain't pretty...
    Chris
     
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  24. Racerx

    Racerx Line Up and Wait

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    Ok, so originally you found oil on the prop. Oil was cleaned and then ground run. No issues. First flight no known issues. Second flight since cleaned, you lose a little oil and the mechanic says it's time for an OH. Did he scope it? Analyze the oil to see if something is making metal? Or just saw smoh time and said it was due for one and gave you a lame explanation? Why didn't we fixate more on the oil being at the farthest forward point possible? It appears to be losing oil...not burning oil.

    When making a 30k decision, get a second or 3rd qualified opinion. We can't scope it or analyze the engine, but a different mechanic can. Your first one I suspect is a little slow right now
     
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  25. 4RNB

    4RNB Pre-takeoff checklist

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    Yeah, I talked to the prior owner, he said the same thing about liking 6 qts.
     
  26. 4RNB

    4RNB Pre-takeoff checklist

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    No, no scope, just visual inspection.
     
  27. 4RNB

    4RNB Pre-takeoff checklist

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    All is not lost...

    Thanks for the feedback, and for putting up with my talking about prop seal when I intended nose seal or crackcase seal.

    I talked to a 2nd mechanic, back home. An ol' timer, with two open 172s in his shop. One owned by airport board member, the other by my future DPE. I was getting feedback on which way to go with this, which engine shop to deal with, safety of flight kind of questions. He thought it sounded worthy of looking at the nose seal. I flew the plane home without issues. Nose seal looked chewed up around the outer edge, parts of rubber material observed gummed up with oil. Mechanic fully certain this was the source of the oil, new engine not needed yet. It was great to see and learn more of this process and I wont care what the bill ends up being, well worth it. I'll probably stay anxious for a week but am looking forward to a third attempt at final checkride prep with my CFI.

    IMG_1059[1].JPG IMG_1062[1].JPG
     
  28. Jdm

    Jdm Pre-takeoff checklist

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    That shaft looks a rough huh? Rusting.
     
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  29. charlie

    charlie Pre-takeoff checklist

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    +1 on the crankshaft corrosion. Probably would not pass inspection!
     
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  30. 4RNB

    4RNB Pre-takeoff checklist

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    We polished.
     
  31. GLDP

    GLDP Pre-Flight

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    Once you get the new crankshaft seal installed make sure to not start or turn the prop for 24hours as Dow 737 is a neutral cure sealant!
     
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  32. 4RNB

    4RNB Pre-takeoff checklist

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    Thanks, I've been instructed. 49 minutes to go, might leave it another day though
     
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  33. Snowmass

    Snowmass Line Up and Wait

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    If I remember when I replaced my seal it was coated with #3 Permatex. No waiting.
     
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  34. George Mohr

    George Mohr Line Up and Wait

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    Just one comment from me... a 1/2Qt of oil per day leak would make you think the entire airplane was washed in oil. Something sounds wrong about this.
     
  35. MBDiagMan

    MBDiagMan En-Route

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    From the original post it sounds as if the case halves are not firmly attached to each other. When this happens they rub together causing all sorts of problems. It does indeed sound like it needs to come apart. There is no way to know what all needs to be done until it IS apart. If I knew enough about the local mechanic to be convinced that he is experienced and competent at this sort of work I would have no problem with him doing a field overhaul. That said, if you are willing to pay the extra money in the interest of getting it back in the air quickly then an exchange from a reputable engine shop could be your best bet. If you decide to put in a different engine, the time savings may not be there since it will involve changes, STC paperwork and such.

    IF your research indicates that the local mechanic is competent, you might consider the reuse of your existing cylinders if they were new only 150 hours ago. That would save money with a local overhaul, but would gain nothing if exchanging the engine.

    Reiterating one point, impart due diligence in learning about your local shop before allowing him to move forward with a field overhaul.

    My $0.02,
     
  36. Tailwind7

    Tailwind7 Filing Flight Plan

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    An the result is????
     
  37. 4RNB

    4RNB Pre-takeoff checklist

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    5 hours or so since nose/front crack case seal changed. Same engine. Runs well.
     
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  38. Tailwind7

    Tailwind7 Filing Flight Plan

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    That's great news! As with our bodies, before doing major surgery get at least 2 or 3 opinions. Hopefully you'll get hundreds of more hours on this engine before you have to overhaul. Whatever you do, keep the powerflow. If (when) you decied to overhaul or swap, do the 160HP STC. That, with the powerflow (plus porting and pollishing), will give close to 180HP (mine got 177HP). You'll lose your ability to use autogas, but that's getting more difficult anyway due to Ethanol poisoning of our auto-gas.
     
  39. MBDiagMan

    MBDiagMan En-Route

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    I hope they checked the case bolts in the process.