Results 1 to 19 of 19

Thread: Spark Plug Frosting ?

  1. #1
    Member Float Pilot's Avatar
    Join Date
    Oct 2006
    Location
    Kachemak Bay Alaska
    Posts
    4,218

    Default Spark Plug Frosting ?

    The other day we had an non-preheated C-182 start for a couple seconds and then quit. It never wanted to start again.
    Yesterday my C-172 battery was dead so I tried hand starting..... It ran for a few seconds and quit.... Then I wore out my shoulder trying to re-hand start...

    Anyway, whenever this happens my buddy always says " We must have frosted the plugs " I have heard this before for a couple other folks over the past 35 years or so ..

    Does anyone have a logical argument of how or why the plugs are frosted in cold weather???

    I always figured I had flooded and drenched the plug with too much fuel or carbon fouled them by running super rich,,,,
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  2. #2

    Default

    The way I heard it, the vaporization of fuel in the cylinder as it is sprayed in there cools the cylinder, precipitating water out of the air within the cylinder as ice. If the ice covers the spark plug, no spark. And I've had frosted plugs before, where there is just no way there is any hint of interest in a start, after initially seeming like it was going to start. Surefire way to avoid it is to preheat.
    14 Days to Alaska
    Also available on Kindle and Nook

  3. #3
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Starting a cold engine makes instant heat inside a cold cavity. That makes steam. Steam sticks to cold things and freezes. It's only happened to me when the temps are cold, like single digits, and I get impatient to get started without preheating. The only cure is to heat up the engine.

    It's hard to imagine flooding a cold engine at start up. It's hard to get enough fuel into my engine when I haven't preheated adequately. Stroking the primer to keep it idling is sometimes necessary. I like preheating better. Electric preheat makes adequate preheating much easier.

  4. #4
    Member Float Pilot's Avatar
    Join Date
    Oct 2006
    Location
    Kachemak Bay Alaska
    Posts
    4,218

    Default

    In my case this Saturday the outside temp was about 32 degrees when I started my airport adventures and it might have been 25 degrees by the time I stopped. Originally I pre-heated the engine until it was warm to the touch, but then I discovered my battery was dead and had to tow the plane to another tie-down with the truck.
    Later when I attempted hand-starting it ran for about 10 seconds and that was it for the day...
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  5. #5
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Probably not frosted plugs. I don't preheat until the temps get below 25* but even at that it takes lots of prime to get my engine started. You need to experiment with your new plane and see how much prime it takes to make it fire off as quickly as possible in different temps.

    When I've hand propped a Lyc 0-320 I've used 4-6 strokes of prime and pulled the prop through with the mags off to distribute the fuel. It popped right off doing that but it wasn't 25*. That would take even more gas. I know you're a seasoned hand-proper so I guess you just need more time to get familiar with the new plane. Remember to have some fun. :-)

  6. #6
    Member Float Pilot's Avatar
    Join Date
    Oct 2006
    Location
    Kachemak Bay Alaska
    Posts
    4,218

    Default

    The time it did start I gave it four squirts of primer and pumped the throttle a couple times. Then I pulled the prop through six times and cracked the throttle an inch.
    I propped her from behind on the starboard side. But it was so slippery and icy that I had a hard time getting back around to the passenger door before she lost momentum. ( falling down a couple times will do that) .

    After that point she would not even think about starting.... I tried several more times for another hour. Eventually it felt like I was going to have a heart attack so I went home.

    The prop on this plane is not indexed all that well for hand-starting. The Cub was ready for the power stroke at 1 to 1:30 position. ( standing behind) This spam can is more like 11:45.

    I have one of the Cessna Aux power jacks on order.
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  7. #7
    Member
    Join Date
    May 2013
    Location
    Talkeetna, AK
    Posts
    62

    Default

    Tannis preheat says they like to see cylinder temps reach 100 before starting in cold weather. If you can do this and plan this into your flight day life may get a whole lot better. You may also have ice in the fuel line causing some blockage. Happened to me once engine quit 100 feet up off the runway. Even with that low altitude I really wanted to turn around… but didn't.

  8. #8

    Default

    I have been a auto mechanic 30 years and have never seen this freezing plugs thing. I have pulled the plugs out of hundreds if not thousands of cold no starts and never seen anything resembling ice, Raw fuel on the plug? Yes all the time. The problem [am guessing- I don't know] is in sub freezing temps you are pulling more liquid gasoline in the cly than gasoline vapors. Vapors explode, [running engine] liquid just burns[non running engine that barks occasionally]
    BTW if a certain poster from the gun forum sees this, I'm just saying.

  9. #9
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Relating car engine experience to airplane engines is a stretch. Most of us are familiar with flooding a stubborn car engine. It's pretty tough to flood an airplane engine. We use updraft carburetors and updraft induction tubes. Horizontally opposed air-cooled cylinders fed from the bottom. No choke. Two massive electrode spark plugs per cylinder working off of independent electrical systems. Even for those of us with electric start the available cranking duration is short. Fuel injected engines are a little different but flooding in the cold isn't usually a problem. Hot starting? That can be a pain. The interesting thing about frosting plugs is that it happens after the engine fires and makes a few rotations. Maybe it's related to the second mag coming on line with different timing. No matter, prevention is the key.

    I have pulled top plugs after a failed cold start and found frost on the plugs. The plugs smelled like fuel but there was no liquid fuel on them. Vaporizing liquid fuel from an updraft system requires heat. Most of any liquid fuel stays in the induction tubes. If you've ever held an airplane carb in your hand and actuated the throttle you've seen a stream of gas shot straight up. The induction tubes don't take a straight path to the intake valves. Work the throttle and all that gas drains out the induction system, through the carb, into the airbox, and into the cowling. A fire risk some of us know too well. For that reason most of us have primers to the cylinders. I've never flooded my engines using prime. Usually the opposite and I don't give it enough. It's surprising how much fuel it takes to start a cold engine. If memory serves Lycoming recommends pre-heating at 10*F and below. TCM says 20*. Most airplane owners try to pre-heat below freezing. It makes life much simpler. Prepping the plane for a winter flight is a pain. To have a failed start and frosted plugs is not the result we're after. Especially with short days and not enough time to heat the engine and save the flight.

  10. #10
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    For the airplane guys, I remembered right. Here are links to TCM and Lycoming cold weather starting procedures. Read the final paragraph of part A in the TCM link. It describes plug frosting.
    http://www.tcmlink.com/pdf2/SIL03-1.pdf
    http://www.lycoming.com/Portals/0/te...20Starting.pdf

  11. #11
    Member Float Pilot's Avatar
    Join Date
    Oct 2006
    Location
    Kachemak Bay Alaska
    Posts
    4,218

    Default

    I finally figured out what this particular 0-320 engine likes....

    I have been preheating the entire engine with my Red Dragon and my engine cover. But it really does not seem to help much with temps that are in the 20s.
    This engine likes 6 shots of primer, then pulling the engine through 8 to 10 times and then two more shots of primer before the turning on the mags with the throttle open about 1 inch.
    It does not like jacking the throttle around before starting and I have to keep somebody in the cockpit to run the throttle so it does not quit before I waddle across the ice to get to the controls.

    My aux power socket is not working.... I tracked the problem to the solenoid that isolates it.
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  12. #12
    Member
    Join Date
    May 2013
    Location
    Talkeetna, AK
    Posts
    62

    Default

    I have heard somewhere in the past that using the primer then pulling the prop over a few times is not good for the cylinders. The term was called washing the cylinder walls and shortened cylinder/ring life. Any truth to this myth?

  13. #13

    Default

    Look I am not agruing against pre heating a engine at all. I am just stating my theory about why cold engines can be hard to start. A airplane engine is not some other world engine that all my experience with cars is worthless. In fact they are just a flat 4 cylinder air cooled Volkswagen motor from 1942.
    No I don't care if its a updraft, side draft, or down draft carb. Or fuel injected supercharged turbo motor.
    Engines airplanes or any other internal combustion engines need 3 things to run- air, spark and VAPORIZED fuel.

    That 'frosted spark plug" thing sounds to me like BS that got passed along till it was a fact.

  14. #14

    Default

    Quote Originally Posted by Jerbear View Post
    I have heard somewhere in the past that using the primer then pulling the prop over a few times is not good for the cylinders. The term was called washing the cylinder walls and shortened cylinder/ring life. Any truth to this myth?
    No. If you wash all oil off the cylinder walls it will sound like you pulled the plugs on the engine and it has no compression. It will not start in this state. Who cares about cranking? Once you fire it up the lube will hit the cly walls and all will be good.

  15. #15
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Quote Originally Posted by Jerbear View Post
    I have heard somewhere in the past that using the primer then pulling the prop over a few times is not good for the cylinders. The term was called washing the cylinder walls and shortened cylinder/ring life. Any truth to this myth?
    Jerbear, When I prime normally and then engage the starter the number of blades before the engine starts is pretty consistent (relative to the outside temp/preheat/etc). When forced to hand prop I figure priming and pulling that same number of blades is a pretty good place to begin hand-flicking. My intention is always to start the engine with the least rotation whether by starter or hand. It's a contest I do with myself every time I start my plane. I've never had a no-electrics airplane so my hand propping experience is limited. I've spent time with a few friends over the years that had no-electics by choice. Fun to watch.

    Float Pilot, what's up with that plane that you need to use external power? My 520 starts fine with an itty bitty Odyssey battery as long as it isn't too cold. Yours should, too. I have grinned at your description of trying to get to the controls in time. Not easy in a 4-seater with swinging doors, I imagine? Just curious, are you selecting one mag when propping? I've never had to (or wanted to) hand prop my Cessna. I wouldn't do it more than once before I fixed my starter issue!

  16. #16
    Member Float Pilot's Avatar
    Join Date
    Oct 2006
    Location
    Kachemak Bay Alaska
    Posts
    4,218

    Default

    My battery (Gill) died during our recent cold stretch. I was not sure that it was the battery until now... ( musical hangar space )
    I put it on a charger with a slow charge, but it smells like sulfur gas when charging and will not stay charged.

    What do you think of the Odyssey for cold weather and which model did you use?

    Stoddards carries the SBS J-16 model which it STCed for a PA-18 and I have read that somebody had it field approved in a 172.
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  17. #17
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Odyssey's perform better in the cold than regular lead-acid batteries. They also hold a charge longer while sitting unused. My 180 has a PC625 on the firewall. The first one lasted better than 10 years until I replaced it after an engine fire. I still have the original as a shop battery. Tough little suckers. If I was replacing a stock battery in the stock location I'd use a 925. You shouldn't need the FAA, by the way. Read AC43.13-2B chapter 10. Odysseys are lead acid and that chapter spells out how you can install one as a minor or major alteration depending on how you install it. An IA can sign it off.

  18. #18
    Member Float Pilot's Avatar
    Join Date
    Oct 2006
    Location
    Kachemak Bay Alaska
    Posts
    4,218

    Default

    Aircraft Spruce wants $46 to ship one via the mail....
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  19. #19
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Batteries Plus in ANC carries most Of the Odyssey line. Stoddards if you prefer the SBS-J16 PMA'd battery.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •