Cold Weather, Remember how to Start Engine

WDD

WDD

Final Approach
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Vintage Snazzy (so my adult children say)
For some of us, morning temps in the 20's and/or a plane soaked overnight in the 20's isn't common, but it does happen. Being something not encountered frequently, let me offer a friendly reminder to review cold weather starting, priming procedures, and what to do with a flooded engine. And check to see how old that battery is.
 
RyanB said:
Hopefully it includes some kind of preheat. I’d hate to be consistently starting an expensive engine in temps like that without any.
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Funny you mention that. Since my airport doesn't have a pre heater to borrow (did I mention I live in the ATL area?), I am now the proud owner of a propane forced air heater. Some interesting metal work and flexible insulated duct tubing from Home Depot and I have a simple pre heater now. Not a lot of BTU's but given it's not "Chicago cold" I'm dealing with, it doesn't need that much to warm it up a bit. I figure if I run it for 1/2 hour or so it should help. I'm thinking of putting the end of the insulated flexible duct tube into the lower cowl flap at the bottom and let it heat the engine compartment from the bottom.
 
WDD said:
Funny you mention that. Since my airport doesn't have a pre heater to borrow (did I mention I live in the ATL area?), I am now the proud owner of a propane forced air heater. Some interesting metal work and flexible insulated duct tubing from Home Depot and I have a simple pre heater now. Not a lot of BTU's but given it's not "Chicago cold" I'm dealing with, it doesn't need that much to warm it up a bit. I figure if I run it for 1/2 hour or so it should help. I'm thinking of putting the end of the insulated flexible duct tube into the lower cowl flap at the bottom and let it heat the engine compartment from the bottom.
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Nice! Just be careful, those kinds of setups can pose a fire hazard if not carefully monitored. A professionally installed Tanis pre-heater is cheap insurance!
 
WDD said:
putting the end of the insulated flexible duct tube into the lower cowl flap at the bottom and let it heat the engine compartment from the bottom
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Fwiw, that's exactly how the local flight school preheats their planes. The have the propane tanks & burners strapped to a dolly, wheel them out to the plane, and shove the flexible duct up into the engine compartment.

Doesn't make it right, and they are required to change their engines at tbo, but they always make tbo.

Here above the Mason -Dixon line, I like a tanis system, but if I lived in the South id probably use a 100w lightbulb in the bottom and a blanket on top for the rare times it's below freezing.
 
RyanB said:
Nice! Just be careful, those kinds of setups can pose a fire hazard if not carefully monitored. A professionally installed Tanis pre-heater is cheap insurance!
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Nice - some day I might have a hangar and this would be a great option.
 
172andyou said:
Fun fact: Lycoming doesn't require preheating until below 10F.
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To be honest, this was more operator error vs "Continentals can't start below 32 degrees". The pre heater I have now is more than likely overkill, but hey, why not.

I also have a brand new battery, as the old one was getting a little weak and acting odd every now and then in the summer.
 
172andyou said:
Fun fact: Lycoming doesn't require preheating until below 10F.
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Agree below 10F is the chance of getting is started is pretty low without a preheat. Below about 25F the chance of getting it started goes down pretty quickly as it gets colder. Consistently getting a start below 25F without a preheat usually requires really knowing what you engine likes, and some don't seem to like anything. The only way to find out what your engine likes is to try different things and often failing to get it to start. Also the chance of a fire in the cowling goes up at about the same rate as the chance of starting goes down.

This is just trying to get it to start. Wear and Tear from starting them without a preheat is a different topic, but a great reason to preheat.
My rule of thumb is I won't even try a start below 30F unless I don't have any other option.

Brian
 
I still have a Tannis in my plane from when I had an unheated hangar. My hangar is heated now so unless I'm travelling in cold weather I tend not to have to worry. There's hot water circulating in the hangar slab (fed by a geothermal heat pump). It's amazing how fast the air recovers after you shut the door again with that much thermal mass.

A few years ago I flew into IAD at Christmas time. I asked the line guy if they could either put it in the hangar or get it close enough to the building to plug in the block heater. The next morning I came out and my plane was not on the ramp. I popped into the hangar to find it sitting there in the middle of this cavernous empty space... with the block heater plugged in. Yeah, I tipped the guy $20.
 
Winter flying in Alaska has taught me a lot about cold weather engine management and I’ve tried pretty much every preheater imaginable, and have created many of my own. Away from power, preheat requires a combustion source. A flame to heat an engine requires attending the flame. Not much fun with -30° and a breeze blowing. That minimizes preheat time to just enough to get the engine started. All the talk about made-up temperature thresholds is amusing to me. I’ve started Coninentals and Lycomings in single digits when I needed to. I’ve frosted plugs, too, and that’s a mission killer so I learned how to avoid it. Preheating below 20° per Continental instructions has worked fine for my engines, including Lycomings. Flying in those temps requires other prep so it’s not a burden until it gets cold enough to hurt. For that? I’ve evolved to 1000w generators and Reiff heaters.

Cold engines 101. Oil pan heaters thin oil and make starters spin better. Faster spinning helps cold cylinders fire more reliably but cold cylinders scuff. Air cooled cylinders are difficult to warm with a sump heater. Cylinder heaters make fuel distribution better and combustion easier, but starting with gooey oil isn’t good for the engine. A combination of both is the best solution. Hot air heaters are almost never used long enough to warm the oil and are probably the worst idea for engine health, especially propane heaters that pump water vapor into the cold engine compartment. Preheating the oil takes hours, not minutes, and quick development of oil pressure is the benchmark you need to shoot for.

In 20°-ish temps? I prime, pull the prop through several rotations, prime a little more, then start. Learn to minimize how many blades go by before the engine fires. Do some hand-propping in winter and you’ll figure it out quickly. Cold engines require more prime. Cold temps require more fuel in flight, too. Make sure your carb provides a minimum of 150° of leaning authority in the temps you fly in. Cover your oil cooler as required to achieve adequate oil temps. Don’t worry about cold CHTs, those are rarely a problem even in sub-zero. Learn what cold temps do to your prop efficiency and limit takeoff rpms if warranted. Dress like you’ll have to walk home.

Winter temps improve airplane performance. Have fun!
 
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A cold start where cylinders reluctantly fire once or twice makes moisture. Moisture freezes to cold metal and fowls plugs. They get covered with fuel-soaked frost crystals and refuse to spark until cleared. The remedy is pulling/cleaning plugs or a thorough preheat. In cold engines the margin between enough fuel and too much fuel is very small.
 
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So much consternation with cold engines on airplanes, yet my car engine fires right up in the same temp. I’m guessing that’s the magic of fuel injection.

Many, many years ago when cars were switching to FI, they had some cold weather starting problems. Would flood because car wouldn’t turn over fast enough for the amount of fuel the FI delivered.

Simple solution - they put larger batteries in, which had enough cold cranking amps to spin the engine fast enough to start.
 
Air cooled vs water cooled/computer controlled fuel distribution and ignition is apples and oranges. I have carbureted and fuel injected airplanes. Standard mags and electronic ignition respectively. Both systems prime directly to the cylinders. Starting issues are the same.
 
172andyou said:
Fun fact: Lycoming doesn't require preheating until below 10F.
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But it sure makes it a hell of a lot easier to start and it's likely a significant add to TBO. Also have a little electric heater on the cockpit floor - makes getting in a bit nicer in the winter.

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Pugs said:
Also have a little electric heater on the cockpit floor - makes getting in a bit nicer in the winter.
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I don't think anyone who has flown someplace with winters is going to argue the comfort angle of engine or cabin heaters!
 
Blanket on the cowling, cowl plugs in and a 1500W space heater blowing hot air through a duct in the bottom of the cowling. Warms things up relatively quick.
 
I always made it a point to preheat below 30 degrees had a small propane heater in a tool box which could run on 12 volt batter. Other choice was a portable generator for the Tanis heater. The final solution was to move to Florida if it gets below 30 I stay home
 
Stewartb said:
Both systems prime directly to the cylinders
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You mean into the intake ports in the heads, right? I haven't seen any aircraft engines (other than diesels) that inject gasoline directly into the cylinder.
 
Yes. I was pointing out that they don’t prime the induction like an 0-300 or other antique engines, or similarly by pumping the throttle on an updraft carb.
 
I went to school last year to become an RV tech. One instructor says, “if you have to use your furnace, you’re RVing wrong”. ;)
 
Wood takes up too much space in the baggage area of the RV, the furnace can be plumbed into the main fuel tanks.
 
WDD said:
I'm thinking of putting the end of the insulated flexible duct tube into the lower cowl flap at the bottom and let it heat the engine compartment from the bottom.
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AV8R_87 said:
Blanket on the cowling, cowl plugs in and a 1500W space heater blowing hot air through a duct in the bottom of the cowling. Warms things up relatively quick.
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When I owned a V-tail Bonanza, the engine operating instructions specifically advised against this way of pre-heating. I used an oil pan pad heater and a big quilt or moving blanket over the cowl. Always the night before flying in northern Minnesota, Wisconsin and lower Michigan. I often flew when OAT was below zero F.

I also put a 100w trouble light inside the cockpit resting on the left rudder pedals to keep the gyros warm. If it was below zero, I would also warm the cabin with an electric heater while I did the preflight. For my tug, I had an electric heater with a dryer tube that I'd put under a blanket over the tug while I was preflighting.

This worked well for me.
 
Us tie down, hangar challenged folks without electricity just have to make do with propane.
 
WDD said:
So much consternation with cold engines on airplanes, yet my car engine fires right up in the same temp. I’m guessing that’s the magic of fuel injection.
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Don't forget water-cooling. Anti-freeze is like an insulating blanket and also allows for better alloys as well as tolerances.

I wonder what Rotax has to say about cold weather operations with the 912iS?
 
Jim K said:
Here above the Mason -Dixon line, I like a tanis system, but if I lived in the South id probably use a 100w lightbulb in the bottom and a blanket on top for the rare times it's below freezing.
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These new LED’s are never going to get your engine warm no matter how long you leave it in there. :)
 
Gilbert Buettner said:
When I owned a V-tail Bonanza, the engine operating instructions specifically advised against this way of pre-heating.
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I wonder what their reasoning was. That air is usually less than 120F, and it uniformly warms up the engine. I don't see any issues with doing that to an engine for an hour or two in cold weather, warming everything up.
If anything, I wonder if their concern is not warming the engine enough, leading to uneven temperatures. I recall some people were against oil pan heaters because it did nothing for the cylinders.
 
It will also warm a lower mounted updraft carb. Maybe vapor lock concern? Can’t really see that, as the carb and engine just are. It going to get that hot.
 
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