Cold Cranking

Discussion in 'Maintenance Bay' started by Chilito, Feb 15, 2020.

  1. Chilito

    Chilito Filing Flight Plan

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    Hi, all. After almost two months, the weather in MN warmed up enough to try to go flying today. It's been hooked up to a battery minder and I went out this morning to plug in the oil pan heater. I came back two hours later, climbed in and primed, gave it some gas and cranked. It caught for about a second, RPMs jumped up, then killed. This process was repeated multiple times with similar results.

    I'm in an unheated hangar, and temps the last few days were below 0F. If it turned over, then killed, what should I try next time? Pre-heat for longer? Entire engine block heat? Wait for warmer weather? More priming didn't help and I didn't want to over-prime. The battery is charged. I think I was just beaten by the cold.

    Thanks for your thoughts.
     
    Last edited: Feb 15, 2020
  2. smv

    smv Line Up and Wait

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    More fuel. If you prime enough that raw fuel starts coming out, you have primed too much. Do not prime that much next time.
     
  3. Stewartb

    Stewartb Final Approach

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    Next time leave the primer out and charged. When the motor falters add fuel. Better yet, preheat better. A couple of hours with a sump heater isn't enough.
     
  4. Dan Thomas

    Dan Thomas Final Approach

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    You DID remember to push the mixture control in, right?;)

    Might have been frosting the plugs, too.
     
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  5. Chilito

    Chilito Filing Flight Plan

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    Mixture was full rich! She wanted to start, but just wouldn't hold on.
     
  6. eb87f

    eb87f Pre-Flight

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    My warrior does that same thing when it is cold out. Pumping the throttle in the lower end of its range keeps it going. I think it just needs more fuel in order to evaporate enough to keep it running in the cold.
     
  7. Huckster79

    Huckster79 Cleared for Takeoff

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    More thorough preheat, those poor cylinders were icy cold... cover the cowl up good with a heavy blanket if you dont have a cowl cover. I only have a sump heater and my cylinders are 80 degrees plus after 8 hrs or so...but you must wrap up the cowl so the heat is retained not just whisped off... our engines are designed to shed heat...



    Theres more to a true preheat than thinning the oil and theres more reason to do it than just to help it start..
     
  8. GeorgeC

    GeorgeC En-Route

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    I spoke with an IA recently who said that keeping a battery on a battery minder 24/7 causes outgassing which results in corrosion of nearby surfaces. OWT?
     
  9. AKBill

    AKBill En-Route

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    Wondering if there is ice blockage in the fuel line. Starts off prime but no fuel from carb.
     
  10. Sinistar

    Sinistar En-Route

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    @Chilito - you didnt pre-heat long enough. I think we're pretty near to each other. It was around -20F Thursday night and single digits Friday until this warm air came in last night. Your plane was in a cold dark uninsulated hangar so even though it was mid +20's today the super cold soak just a day and a half early needed more than just 2 hrs. Around here if the wx is looking flyable I recommended plugging in the night before. Give it around 8hrs or more. My coldest start was around -5F this winter. I remote pre-heated the night before and I used 4 shots of primer instead of a normal 2-3 in the summer.

    Also, at a minimum get some cowl plugs if not already using a full blanket. We just use cowl plugs inside the hangar but will eventually get a blanket.

    Another trick is to place a small ceramic tipswitch heater in the cockpit right when you arrive. With the doors and windows shut the inside of the 182 will get to about +45F and heat up the radios and seats while taking extra time to preflight. Just dont leave it unattended.

    You should have another shot tomorrow.
     
  11. FORANE

    FORANE Pattern Altitude

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  12. denverpilot

    denverpilot Tied Down

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    Outgassing from a lead-acid battery would be hydrogen, not acid. Apparently chemistry wasn’t his strong suit.

    I have seen big non-aircraft lead-acid batteries that were in poor shape “boil” even under light charging and there was a little acid “spitting” around the vents on a non “sealed” battery. (No battery is fully sealed. There’s always a vent somewhere.) That stuff could become atomized and airborne I suppose for very small distances.

    Moral of that story would be don’t keep limping a weak battery along with any charger.
     
  13. Dan Thomas

    Dan Thomas Final Approach

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    Batteries spitting acid have been overfilled. If one bothers to consult the information brochure that comes with a new battery, one reads that the manufacturer says to put the battery on charge and only once it's actively bubbling is the electrolyte topped up to the bottom of the split ring. The bubbling displaces the electrolyte, swelling it, along with some heating of it causing expansion, and if people top the batteries up to that split ring while it's just sitting in the airplane doing nothing, the electrolye will expand up to the tops of the splits and now the gas can't get out. It pushes acid out instead, making a corrosive mess and losing acid so that more topping up with water dilutes it and weakens the battery.

    When I topped any battery while still in the airplane, I brought the levels up to halfway between the tops of the plates and the bottom of the split rings, and never had any acid spitting out. As long as the plates are covered, it's fine.

    From http://www.gillbatteries.com/Content/PDFs/flooded_service_manual.pdf

    7.3.2 Charge the battery when water is added. This will mix the electrolyte and water to provide a homogeneous electrolyte. Continue charging until the voltage and specific gravity readings are constant over three readings taken over three hours at approximately equal intervals.

    7.3.3 Adjust electrolyte level (just below the vent well) at the end of the charge, with the use of a hydrometer. Remember, the electrolyte will heat-up and expand as the battery is being charged.
     
    Last edited: Feb 17, 2020
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