Lycoming O-360 kick back when cold

Discussion in 'Maintenance Bay' started by jd21476, Jan 12, 2020.

  1. jd21476

    jd21476 Pre-takeoff checklist

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    I had this happen twice so far and I have only owned the plane for two months. When I crank the engine it seems to suddenly have a kick back and the starter disengages. I let it sit for a minute and the she starts and runs fine. It did it when I tried to start her when it was 27 degrees out when I bought her in Idaho and the. She did it tonight and its almost 55 degrees in Socal.

    What causes this and is it harmful or fairly common?
     
  2. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    which start method do you have? slickstart?
     
  3. AKBill

    AKBill En-Route

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    Maybe disengaging starter a bit early?
     
  4. Chip Sylverne

    Chip Sylverne En-Route

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    Fear is the poison of our lives.
    When it starts, does it normally fire off on release of key?
     
  5. Clip4

    Clip4 Final Approach

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    Sounds like you have a timing or stuck valve issue.
     
  6. charlie

    charlie Pre-takeoff checklist

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    Sounds like a shower of sparks starting system not operating properly.
     
  7. Stewartb

    Stewartb Final Approach

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    Sounds like the starter speed may be slow.
     
  8. retpd2001

    retpd2001 Line Up and Wait

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    That happened to a friend of mine caused by (he thinks) a weak battery. In his situation, it took a chunk of his starter case off.
     
  9. Dan Thomas

    Dan Thomas Final Approach

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    Starter disengaging? Sounds like it's kicking forward, not back.

    If it's kicking in reverse, you might have a bad ignition switch. That switch will shut off the non-impulse mag during start so that it can't fire at the advanced position, something that would cause kickback.
     
  10. Weekend Warrior

    Weekend Warrior Pre-takeoff checklist

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    Been there, done that. Kickback is not condusive to long starter life. @jd21476 get it figured out, as you've probably been lucky so far.
     
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  11. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    Primary reason is bad timing.
     
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  12. jd21476

    jd21476 Pre-takeoff checklist

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    I am going to have my mechanic look at it. My assumption is that the starter is kicking off. Once it starts she runs just fine.
     
  13. Arnold

    Arnold Line Up and Wait

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    I've had this happen a couple of times with the Luscombe on colder days. Fortunately the starter was not damaged and all five fingers are intact.
     
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  14. Doug Reid

    Doug Reid Pre-takeoff checklist

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    Best answer.
     
  15. Chip Sylverne

    Chip Sylverne En-Route

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    Depends on the system. If it's an SOS, timing could be fine, but the advance points aren't being grounded either by the switch, broken p-lead or something else. The OP never told us what system he has.
     
  16. jd21476

    jd21476 Pre-takeoff checklist

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    Im not sure which system I have. Im fairly new to the plane.
     
  17. Stewartb

    Stewartb Final Approach

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    If it's a timing thing you risk this. In this case the Skytec starter survived.

    7068F695-B55F-4F4B-9987-A39AB436798B.jpeg
     
  18. Doug Reid

    Doug Reid Pre-takeoff checklist

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    Still a timing issue....whether sos or impulse coupling...both should fire near TDC on startup.
     
  19. Silvaire

    Silvaire En-Route

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    Since it's intermittent and happened when it was cold my guess is the impulse coupler. Sometimes they get a bit gummed up and especially in cold weather with 100W oil the shoes stay in and don't catch the pawl (or whatever it's called) Result is the plugs fire at 25 deg advanced and you get the kick-back. Could be that the non-impulse mag is not getting grounded by the ignition switch as Dan said but I think then it would tend to happen all the time. You can check this when it's cold, before starting, with switch off turn prop by hand and listen for the 'click' of the impulse. Solution is to have your mechanic do a 500 hr on the mags and clean up the impulse coupler.

    To answer your question: yes it's harmful. Get it fixed.
     
  20. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    Slick Start,, doesn't have impulse couplings.
    Even if they were used, that happening is very remote.
    Next chance you get, snap a mag and see how strong that spring is..
     
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  21. Chip Sylverne

    Chip Sylverne En-Route

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    Fear is the poison of our lives.
    When you turn the key and the engine is cranking, do you hear a buzzing sound coming from under the panel?
     
  22. jd21476

    jd21476 Pre-takeoff checklist

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    My mechanic is going to look at it this Friday when I get back in to town.
     
  23. mondtster

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    What kind of plane is it? I don't see where you've posted that information anywhere. The type of airplane isn't an absolute way to determine what type of starting system you have but it can sure help narrow things down.
     
  24. jd21476

    jd21476 Pre-takeoff checklist

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    Its a Piper Comanche 180
     
  25. Silvaire

    Silvaire En-Route

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    It's not the spring Tom, it's only gravity that causes the counterweights to extend and catch the pin. As soon as the mag begins to spin the counterweights retract and no longer make contact with it.

    Anyway, I didn't see that he had a Slickstart so this is all irrelevant.
     
  26. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    if it isn't the spring, see if it works when the spring is broke.
     
  27. Silvaire

    Silvaire En-Route

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    It isn’t the spring that causes it to not catch the pin, it’s just a gummed up counterweight. If it doesn’t catch the pin when you crank it over it doesn’t work even if it has a perfectly good spring and the plug fires at the advance setting that the mag is timed to. That’s what causes the kickback.
     
  28. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    What ? think you best review your basic theory of a impulse coupling.
    If the spring is broken it doesn't catch the pin. it will not fire, simply because the rotor is way out if time, and does not have any energy stored in the mag.
    remember if the coil is not energize until the spring is unloaded as the spring is released.