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Thread: The story - Engine trouble - now complete

  1. #1

    The story - Engine trouble - now complete

    Folks, I wish you all a Happy and Prosperous 2006.

    As you know (if you have read the musketeermail for
    the last 6 months or so), I experienced some problems
    with my 1975 Sierra MC 360 engine. Here is an overview
    and some of the things we found during the process.
    This may help you in determining a course of action
    should you get some of the signs and tell-tales
    yourself.
    The story started in about June of 2005 where suddenly
    the number 3 cylinder top plug disintegrated (at least
    the ceramic part of the plug) and we subsequently
    found that the bottom plug was loose. New plug
    installed and bottom plug tightenend resulted in the
    engine to be running OK again. A few weeks later, I
    started to notice that the engine developed 2-3 second
    long slight vibrations that would go away, just to
    start again some minutes later and.. unexplicably, the
    engine would change revs ( sound and general behaviour
    )etc in right turns only. Within 2-3 flying hours I
    also noticed that the oil temp was up about 1 1/2
    needle width , still well in the green , but
    definately different. We suspected the vernatherm and
    changed that out for a new one. No change, so it was
    not the vernatherm. By now we are getting into the
    summer in California and the engine is now running
    quite hot, about 1 needle away from red , the engine
    is not running right and I am getting more than
    concerned. I am also seeing the the governor no longer
    keeps revs totally constant.There is up to 50 revs
    variance ( again very noticable in turns to the right)
    which I can observe because of my Horizon electronic
    tach and now I am suspecting the prop/ governor part
    of the airplane. Next thing, get the prop dynamically
    balanced, it was already well within specs but now it
    was pretty perfect ( note I had a 3 blade prop
    installed about 50 hrs ago and this was just one of
    the things to check out). Thus, we pulled the governor
    and had it rebuilt ( it was never been touched
    before.... hint... the governor should be rebuild at
    Major overhaul), total cost including a new type shaft
    that needed to be installed was $ 1,053.00. With all
    the signs sofar, I was getting concerned that we now
    had looked at all systems except the Magneto's (which
    also where close the the 500 Hours) but they seemed to
    be working absolutely fine. So, the next thing was to
    get oil analysis done. The verdict , the engine was
    making metal and the recommendation was to first do a
    compression check, then a boroscope and then see what
    needed to be done next. Compression check resulted in
    ALL FOUR cylinders being at around 74/80 (note: engine
    had been Majored only 340 hours ago). Boroscope
    results did not show anything conclusive. So we did
    not find anything BUT clearly there was something
    wrong. We decided to pull cylinder number 3 (see above
    why). Turns out that this cylinder is WORN out,
    hatching is pretty well gone, piston pin marks are
    showing on the cylinder walls from top to bottom.
    rocker arms WORN OUT TOTALLY. Yep, we knew we had a
    big expensive problem. We pulled the other cylinders
    and we had the same issues. Here is some of the things
    we found: over size cylinders and wrong rings
    installed ( based on the manuals). Now we also were
    going to check the oil impellers ( oil pump) because
    we could not find the actual entry in the engine log
    that the oil impellers had been changed to the later,
    steel version, during the major overhaul. It turned
    out it had been done BUT the oil pump housing was the
    WRONG part number. So we changed the housing at $
    231.00 which also necessitated the impellers to be
    changed at $ 250.00. Better safe than sorry, and I now
    am sure that this AD has been taken care of as
    designed. By now, it was October and we were trying to
    do some cost control and we were looking for cylinders
    that would not cost $ 1,800 each as per the official
    price list and we were able to find a set of 4 first
    run cylinders at a very good price . We purchased 4
    new pistons and piston pins as well as a whole new set
    of rocker arms and of course all other small parts
    needed for the top overhaul. We pulled the magneto's
    and got them rebuilt. I have been told that next time
    they will have to be replaced. So we now had
    everything together to start re-assembling the engine,
    complete with all the fittings and probes for the new
    JPI 700 which I wanted to get installed to make sure I
    had a "look inside each cylinder" with the hope that
    any change in cylinder behavior would be noticed by
    this computer. The installation of the JPI alone took
    29 Hours of labor but I know that it is absolutely
    worth it. The mechanic who rebuilt my engine has 35
    years of experience with these Lycoming engines and is
    methodical , precise and understands engines.I got
    charged 95 hours for the total job ( excluding the JPI
    installation), including the oil pump work, the
    governor work ( take out and re-install). I think that
    was an extremely fair number. So last week we went up
    to check the engine out. First hour up and flying
    mostly at 2600 revs and 26 MAP, wheels down and let
    the engine run and work ( in the vicinity of the
    airport) with some changes in revs/ MAP between max
    and 2500 Revs. Temps measured with the JPI where
    within 20 degrees between the 4 cylinders with number
    3 and 4 ( closest to the fire wall) being the
    "hottest" and oil was steady at 195 degrees ( outside
    temp about 55 degrees). Second hour we started of with
    running her pretty hard for the first 20 minutes, then
    climb up to 10,000 ft to make sure the engine would
    stay steady in the long climb. Climbing, full fuel, 2
    people on board was 1000 feet per minute (3 blade
    prop) and even at 8,00 foot still more than 500
    ft/min. Oil temp was steady at 205 degrees. No
    vibration, no shaking and no change in right turns .
    Engine is running smooth and used 1 quart of oil the
    first hour and less than 1/2 in the second hour. Total
    bill equal to a brand new small Honda car!!
    Lessons learned : get oil analysis regularely, get a
    JPI type monitor installed. This MAY have indicated
    the problem earlier and I MAY not had to do a TOP
    overhaul.
    My mechanic suggests the following had happened: Nr 3
    cylinder was running hot (could not be detected with
    the basic Fuel Lean gauge) and when the bottom plug
    got lose may have started to run lean. That might have
    blown the ceramic of the top plug.. Now cylinder nr3
    is basically damaged and then,the 3 other cylinders
    start to get affected and start running hot... then
    the obvious wear and destroy cycle takes over.

    Best regards

    HarryR



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  2. #2

    The story - Engine trouble - now complete

    On Mon Jan 2 9:38 , Harry Roussard <hroussar@yahoo.com> sent:
    (note: engine had been Majored only 340 hours ago).

    ---

    Hi Harry -

    Got any info on who did the 'major' and didn't do any of the other stuff like
    rebuilding the Mags, right? Sure doesn't sound like they even replaced the
    Cylinders - 2,300 total on the cylinders seems about a limit to me, for them to
    be totally worn out.

    Also, all the 'mistakes; on the Oil Pump AD sould seem plenty important enough to
    go to the FAA with.

    Can you go back for some $$ relief?

    Best to you this new year!

    Bill Howard
    BeechSportBill
    N1927W 1973 Sport 150
    Beech Aero Club NorthWest Region Director
    ---- Msg sent via @bmi.net Mail v4 - http://www.bmi.net


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