Top overhaul

Discussion in 'Maintenance Bay' started by dogman, Jul 23, 2005.

  1. dogman

    dogman Pre-takeoff checklist

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    Aircraft ownership can be a real pain sometimes.

    Anyway My pa-32-Six that I have had for almost 3 weeks was all of a sudden showing an increase in oil consumption.Went from a quart-8hrs to a quart-6hrs. Seems to be Blowing it out the breather vent on the belly. No signs in the exhaust. So the local Mech and I checked the Compression Sure enough low on NUMBER 3.

    So my question 1050hrs on a factory reman. I am thinking I will just do all six!
    I am hoping I can make close to another 1000hrs with 6 new cylinders?


    What would you do????

    I have 33 hrs in it since the 1st of June and the Oil consumption has been just what the prev. owner said. until now.
     
  2. TangoWhiskey

    TangoWhiskey Touchdown! Greaser!

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    How much oil are you putting in? It will blow out anything over a certain level.

    What was the compression on #3 during the pre-buy compared to now? Has it changed?
     
  3. Gary Sortor

    Gary Sortor Pre-Flight

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  4. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    I'd do this one and see what happens, you may have broken a ring, and the others will never do that.

    But you may have just stuck a ring in it's groove and be OK untill it happens again.

    It's a crap shoot, I'd deal with each issue as it arises.
     
  5. Jeff Oslick

    Jeff Oslick En-Route

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    I'd run it hard for an hour or so and recheck the compression. To give you an idea of how much compressions can vary, during our annual our #3 was at 55/80. Sounds bad? Well, extenuating circumstances caused the plane to not have flown for the previous 3 months, and all it had was a 15 minute runup before the compression check (out of annual, not legal to fly). After the annual, we rechecked #3 after about 10 hours of flying in a week and good hour of flight right before the check, and sure enough it was back up to 74/80 (same mechanic, same testing equipment).

    YMMV, but I don't think I'd do a full top overhaul for just one bad cylinder - take 'em one at a time, that's why their built to be replaced. Yes, if I had 3 bad cylinders, I might look at doing a full TOH, but not for one.

    Jeff
     
  6. dogman

    dogman Pre-takeoff checklist

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    The compression went from 74 to 50.
    I keep the oil level at 10qts thats where the pevious owner kept it. I had been told that some of these engines will blow the first qt or 2 out so just kept it where the previous owner ran it
     
    Last edited: Jul 23, 2005
  7. dogman

    dogman Pre-takeoff checklist

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    I guess I am trying to keep it up and running with out having it down now for a couple of days and the again in another month?? The other thing, I use it on a lot of 300 to 500mile XCs and thinking that I would prEvent setting somewhere I do not want to be, with some Mech. I do not know changing the next Cyl.
    May be I'm over reacting just like to know it was right.
    So would I realLy be putting myself in a better postion by doing them all or by just the one??

    Am I wasting money or am I preventing possible problems?

    Like you said "ITS A CRAP SHOT"!!
     
  8. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    OK, we run it hard for a couple hours, and then find out it had a broken ring, what now?
     
  9. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    OK here is what I would do..

    Have a look in th cylinder thru the spark plug holes and see if there is any sign of a groove starting.

    IF YES, change the cylinder.

    IF NO, replace the bottom spark plug, bring the cylinder up on compression stroke, back down to mid position 90 degrees BTDC and fill the cylinder with a qt of MMO, replace the upper spark plug and continue to advance the piston toward TDC, until restance is felt.

    allow the engine set as long as you can, remove the bottom spark plug and rotate the engine until the MMO is cleared, and replace every thing and start the engine, run it.

    at 10 hours recheck the cylinder. if still low on compression remove the cylinder and find the cause.
     
  10. dogman

    dogman Pre-takeoff checklist

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    We will give it a shot!

    Thank you
     
  11. charlie

    charlie Pre-takeoff checklist

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    Six new cylinders will without a doubt last to 2,000 hours. The six you have now that were new 10050 hrs ago also ought to make it unless they've rusted or been severely abused. if the sick one doesn't cure itself have it repaired. From my experience operating about 1500 hours in three different Sixes they do the best oil consumption starting with 9 quarts. Charlie Melot Zephyr Aircraft Engines
     
  12. dogman

    dogman Pre-takeoff checklist

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    Thank you Charlie and Tom I think you have convinced me to Change the one cyl. and just keep an I on it. If I do get the point of changing 2 more Cylinders before TBO I will just do the rest at that time . Thank you.

    Jon
     
  13. Anthony

    Anthony Touchdown! Greaser!

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    I had very low compression on my #1 Cyl. two years ago (Lyc. O-360 AK4 with 1,150 SMOH). We sent it to Mattituck and there was a crack in it. I replaced that cylinder and the engine has been running great for the last 300 hours (knock on wood). The other three cylinders were/are showing consistant compression in the mid to high 70's. Much cheaper than replacing all four (or six in your case).
     
  14. Dave Siciliano

    Dave Siciliano Final Approach

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    I didn't catch what type engine this is. On the big bore Continentals, few are making TBO with original cylinders unless really run hard--like 500 hours per year. We did a survey on the Bonanza net and AvSig among other sites and no one made TBO with post 1991 Contis unless in the above circumstances. The 470s and 360s seem to do much better.

    There are two lines of thought on the big bores: since they're probably not going to make it to TBO, do you want to get 'em all topped at once and have it done, or do 'em one or two at a time. If you're concerned about down time, detachability, having the same folks do the work with the same cylinders; getting it done all at once is advisable. If those things are secondary to cost considerations, do them as needed.

    Having an excellent relationship with your mechanic and confidence in him or her is essential to any plane owner. If this guy is good at what he does, and you have confidence in his ability, sounds as if you need to think about cylinder (s) changes. If he's not good and doesn't have your confidence: change mechanics as soon as possible.

    Best,

    Dave
    Baron 322KS
     
  15. Anthony

    Anthony Touchdown! Greaser!

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    Dave. Its a Lyc. IO-540, in a Cherokee Six. But I see you logic on the Continentals. My friend with the V35B and Con. IO-550 sweats every time he gets an Annual. But, so do I. :)
     
  16. Dave Siciliano

    Dave Siciliano Final Approach

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    Thanks Anthony!! The 540 Lycoming has had a completely different set of issues, and , since I don't have one and have never owned one, I won't speculate. Of course there were two ADs on these just a while back, but that's not the issue. In the position described, unless you really know a lot about how these things really work like Eamon, you have to pick a mechanic you believe in and go with his recommendation. It never hurts to check and learn more, but relationship management with your A&P, IA is essential. I actually fly my plane to Gainsville, Texas rather than having work done on field for this reason.

    If I was to rebuild or top and engine, I'd probably not use my local guy. Just like you use a GP in medicine and specialists in areas, once you go inside the engine, I'd go to someone that specialized in engines if possible.

    Best,

    Dave
    Baron 322KS
     
  17. dogman

    dogman Pre-takeoff checklist

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    I have a local Mech. I use to help with Comp. Checks and little minor stuff (oil changes Spark plugs and such ) but when it comes to the other more important stuff I have a mech that is 200miles away that I use. He will come here and do work just pay him for time and Exp. It is worth for someone you trust and know will no scrimp or cheat you. I like to error on the side of caution when it come to the engine. I do not have that," it will be alright attitude". I get to the Mech. and he checks it out and either fix it, replace it. I like piece of mind in the air. I am sure there are people that get away with the bare minimum maint.. but I would not be that lucky and definitely that bold to think I will get away with that new noise I here to day that I did not hear yesterday"lets get it look at". Or the Oils consumption is going up MMMMMMMMM!!!!

    May be I'm to cautious but How can you be.
     
  18. Stache

    Stache Pre-takeoff checklist

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    As an A&P/IA here is what I would do. Soap the cylinders one at a time and add air to the cylinder just like a compression test. With the cylinder soaped turn the proper and run the pistion up and down and look for signs of bubbles.

    Many times a cylinder will pass a compression test and miss a crack about half way down. A soap test will find the crack. Seem simple and it works. If you find no cracks its time for a bore scope of all the cylinders it cheaper than pulling all the cylinders and give you a good look at the wall and valves.

    A set of cylinders should make it well past TBO without a top overhaul with proper care.

    Just one man opinion.

    Stache