Cold weather starting

Is this true? I thought heat expanded while cold temps resulted in shrinkage.
It's the cold-thickened oil in narrow places like bearing clearances and piston-to-cylinder interfaces that make the engine hard to turn.

Clearances between the piston and cylinder will actually increase in the cold. The steel cylinder has a rate of linear thermal expansion (or contraction) half that of the aluminum piston. Clearances are larger when cold and close up when hot. The main and cam bearing clearances might tighten somewhat, being in an aluminum crankcase with a steel shaft, but since the diameters are much smaller the changes are small.
 
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Some people do tend to worry about it too much.
I don't even order my vehicles with a block heater. Run 5w30 oil, just start them up, let idle for a minute, and drive off.
Yeah, but you live in the southern BC interior where the temps seldom get that cold. I grew up in Kamloops and we didn't plug things in there either. When I moved to the prairies it was a much different story. The mineral-based oils we use in airplanes have huge viscosity shifts as the temperatures drop, and as I pointed out earlier, at -10°C a W100 oil will barely pour. 80 isn't much better. That makes engines stiff and it makes the oil pump's job tough. The pump has to suck that oil up some distance and it will generate vacuum instead if it can't get the oil, and vacuum has poor lubricating qualities.
 
Myth. If you rotate the prop backwards and your vacuum fails because of it, than it was already about to go bad anyway. Mags don’t fire going backward, so rotating the prop opposite to its direction of rotation is the safest way to move the prop by hand for storage or what not.

I heard that moving it by hand, especially for “whatnot,” can make you go blind. Hairy palms, at the very least. Too much of it, too often, will definitely cause your pump to fail. And, while you’re at it, be REALLY careful where you put those cowl plugs!
 
So then I should have seen bearing damage in my IO-520A since I have often started without preheat at temps close to zero F many times. But I have not and I would know since I do my own major overhauls. And remember that the Porsche aircooled engine was BOTH an auto engine and an aircraft engine. When I asked a Porsche dealer shop about preheat they thought I had lost my mind. And note that Lycoming says there MIGHT (a classic weasel word) be some increased engine wear starting below 10 F.lycoming preheat.jpg
 
I still want to see a verifiable video of you starting a big continental at 0* F with no preheat. To make it interesting do it with an o-470. How many years will we need to wait to see zero F in Arizona?
 
And note that Lycoming says there MIGHT (a classic weasel word) be some increased engine wear starting below 10 F.
Engines are just too expensive not to treat them with proper care. That last sentence alone would be enough for me to begin pre-heating and save on as much mechanical wear and tear that I possibly could.

YMMV
 
My car most certainly does have 15-40 Delo oil in it all year around. It sits many months at KGWS and I am hoping the thicker oil will cling longer. And not all older cars even had scoops. My 1926 Model T just dipped the rod ends. The Chevy 6 of the 30s and 40s with scoops was considered a very good engine which is why it outsold Ford and no oil pressure to the rods. A fast turning bearing will self pressurize. While pressurizing is better you are comparing 50,000 miles of driving without rod oil pressure to a few seconds at start up.

When I majored my sometimes very cold started engine the crankshaft wear was under two ten-thousandths of an inch which is easily determined by measuring diameters over oil groove to the rest of the journal.
 
I still want to see a verifiable video of you starting a big continental at 0* F with no preheat. To make it interesting do it with an o-470. How many years will we need to wait to see zero F in Arizona?
FYI on Janauary 9, 1978 Hawley lake reported 52 degrees F below zero. Flagstaff under minus 30. You need to retake geography. Starting at zero is very difficult WHICH I ALREADY SAID. The problem has nothing to do with with bore diameter but with the low vapor pressure of AVGAS. Where I live, six miles from Mexico, we hit 12 below. Lots of broken water pipes.
 
Time for some hard theoretical data -

Aircraft engines have an aluminum case whereas car engines have a steel/cast iron case, but the thermal expansion coefficient ratio between aluminum and steel are nominally 1:2. Chilling an aircraft engine to subzero temps can reduce the clearance of several bearings including the the main bearings to near zero. Admittedly aircraft con-rod bearings are steel against steel. But if this doesn't get you, consider that the leakage from bearing clearance goes not only with inverse of the viscosity (measured in centistokes), but also directly by the CUBE of the clearance. This leakage has to lubricate all of the really expensive surfaces (like the camshaft etc and the cylinder bores) inside an engine. Under cold start conditions, this leakage may be 1/1000 the volume at operating temperatures. In order to have a complete lubrication, the leakage has to be a fog of oil in the crankcase - and not simply occasional blobs of oil.

Engine manufacturers seem to have made an unassisted cold start limit of about 5000 Centistokes and an operating upper temperature limit of 20 Centistokes. That's a ratio of 500:1 just based on leakage. Now compound the reduction of flow due to thermal expansion.

Com'on give your engine a chance, and quit comparing it to a car engine:confused:.upload_2019-11-10_16-3-5.png
 
Time for some hard theoretical data -

Aircraft engines have an aluminum case whereas car engines have a steel/cast iron case, but the thermal expansion coefficient ratio between aluminum and steel are nominally 1:2. Chilling an aircraft engine to subzero temps can reduce the clearance of several bearings including the the main bearings to near zero. Admittedly aircraft con-rod bearings are steel against steel. But if this doesn't get you, consider that the leakage from bearing clearance goes not only with inverse of the viscosity (measured in centistokes), but also directly by the CUBE of the clearance. This leakage has to lubricate all of the really expensive surfaces (like the camshaft etc and the cylinder bores) inside an engine. Under cold start conditions, this leakage may be 1/1000 the volume at operating temperatures. In order to have a complete lubrication, the leakage has to be a fog of oil in the crankcase - and not simply occasional blobs of oil.

Engine manufacturers seem to have made an unassisted cold start limit of about 5000 Centistokes and an operating upper temperature limit of 20 Centistokes. That's a ratio of 500:1 just based on leakage. Now compound the reduction of flow due to thermal expansion.

Com'on give your engine a chance, and quit comparing it to a car engine:confused:.View attachment 79631

My girlfriend drives a new Kia, it has an aluminum engine in it. Her previous car was a Honda, it also had an aluminum engine. Our snowmobiles and motorcycles have aluminum engines, and what gets started in the cold more than a snowmobile....she never plugs them in, or preheats in any way, and our snowmobiles sit in a cold enclosed trailer out in the yard with no heat.
 
I dare you to drag race (a takeoff equivalent) the Kia or Honda when it's still cold. Especially if it last saw oil 6 weeks ago.

A snowmobile has prethinned oil+gas in it.
 
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I am totally aware of the different coefficients of thermal expansion between steel and aluminum but, apparently, the strength of the oil film is not breached. Proof? Of course. If the mains went metal to metal explain the following: How would you be able to easily hand turn the prop at zero ? How could you start air cooled Porsche engines at subzero temps which consist of aluminum or magnesium crankcases over steel crankshafts? How could Lycoming only worry about some, maybe, minor adverse affect of below 10 degree F starting no pre-heat. Why hasn't my engine ruined my main bearings starting close to zero? I once did the math and if an engine were assembled with minimum crankshaft clearances at 70 degrees F you could get into thermal interferences at something like 40 degrees.

Once again needing pre-heat at temps at which you can even start and engine using AVGAS is BS. But attacking cherished beliefs is never popular.
 
https://www.yamaha-motor.ca/products/details-build-price.php?model=5051

Small engine running at high speeds - comparatively thin oil (?) - liquid cooled. Not appropriate for direct propeller drive. Wanna fly behind it?

Lycoming only worry about some, maybe, minor adverse affect of below 10 degree F starting no pre-heat. They'll $ell you the new cam$haft - even if it is an "H" series engine. The "splash lubrication" is very incidental, with no features on the spinning stuff to direct lube onto other critical surfaces. The oil film is obviously heated from film shear. I don't think the clearances in A/C engines can go all the way to zero unless the temps are well below zero F, but spun bearing shells are not unheard of.
 
As I said before people worry about it too much.
My oil sump heater plugged in a few hours, no cowl cover, has been good enough for decades, on multiple airplanes. If I was somewhere that got down to -40 I would probably buy a cowl cover and plug in my sump heater for 5 hours instead of 2 or 3, maybe 4. Again, don't over think this.
 
https://www.yamaha-motor.ca/products/details-build-price.php?model=5051

Small engine running at high speeds - comparatively thin oil (?) - liquid cooled. Not appropriate for direct propeller drive. Wanna fly behind it?

Lycoming only worry about some, maybe, minor adverse affect of below 10 degree F starting no pre-heat. They'll $ell you the new cam$haft - even if it is an "H" series engine. The "splash lubrication" is very incidental, with no features on the spinning stuff to direct lube onto other critical surfaces. The oil film is obviously heated from film shear. I don't think the clearances in A/C engines can go all the way to zero unless the temps are well below zero F, but spun bearing shells are not unheard of.

My point is that it is aluminum, and a few have been saying that the problem with starting an airplane engine when cold is its aluminum.
Yet I just start up my snowmobile, let it idle about 1 minute, and off i got at full throttle, no issues.
 
Aircraft engines have a number of cold (and other) related issues including differential expansion, thick oil. cam/crank layout. oil pump feed tube, operating environment, air cooling, hideously expensive parts, certification, low vapor pressure fuels, and a dinky battery, all of which combine before an operator has to decide weather to preheat.

The only benny is that you can hand prop it if you dare.......
 
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Ever seen how small a snowmobile battery is?
An airplane's seems large in comparison. And 15w50 like I use, really isn't that thick.
 
My point is that it is aluminum, and a few have been saying that the problem with starting an airplane engine when cold is its aluminum.
Yet I just start up my snowmobile, let it idle about 1 minute, and off i got at full throttle, no issues.
2-stroke? Keep doing that and you’ll either cold seize the engine or gall the barrels. Lord knows I’ve done that a few times, but in general comparing a 2-stroke to an aircraft engine is apples and oranges. My 4-stroke sled? Preheat is required any time it gets near or below zero F. With 0-30 oil it isn’t resistance to spinning, its how cold cylinders don’t like to fire with available fuel. That that’s the same as with airplanes. Cold temps require a lot of gas. Frosting plugs is common. I’ve got lots of sled experience down to -50F. Riding in those temps isn’t fun. Breaking down is less fun.
 
2-stroke? Keep doing that and you’ll either cold seize the engine or gall the barrels. Lord knows I’ve done that a few times, but in general comparing a 2-stroke to an aircraft engine is apples and oranges. My 4-stroke sled? Preheat is required any time it gets near or below zero F. With 0-30 oil it isn’t resistance to spinning, its how cold cylinders don’t like to fire with available fuel. That that’s the same as with airplanes. Cold temps require a lot of gas. Frosting plugs is common. I’ve got lots of sled experience down to -50F. Riding in those temps isn’t fun. Breaking down is less fun.


4 stroke.
Actually as mentioned above, turbocharged 3 cylinder 4 stroke. I have had a lot of cars, pickups, planes, motorbikes, snowmobiles, and more, have yet to see an engine problem with any of them. The only engine failure I personally have had, was a used lawnmower I bought when 18 years old from a garage sale. About a decade after buying it the motor quit, and I instantly knew why, since I was mowing a really rough area of the yard and it hit a pile of dirt. I took the the cover off, and got to the flywheel, sure enough it had broken the timing key. I made a new key from some scrap aluminum by filing it down to the right size, loosening the flywheel and turning it back until the slots were again lined up, using my homemade key, put it in and put it back together, it fired right up and ran again. It was my rough area mower after I moved to an acreage about 5 years after buying it, and buying a rider for the big lawns. I finally after owning it about 15 years, and remember it was used when I bought it, gave it away to a family down on their luck, and they needed a mower that ran
Most engines are a lot tougher than people give them credit for.
And GA piston engines are an extremely simple design, very low rpm, and low power output for their large cubic inch size. If any engine should live a long happy life its a GA engine. A 520 cubic inch engine in a car or pickup would be making about 2 to 3 times the power, started up cold and just driven away harshly, rarely serviced, no fancy oil changed every 50 hours, asked to spin to 6k plus rpm regularly, and yet it will pile on thousands and thousands of miles, year after year. My motorcycles get started up, idle while i put on my helmet, and off I go, I spin them to 10k or 12k rpm seconds after leaving my driveway, yet years and years later, they run like new. Change the oil twice a year, new spark plugs every 3 years, clean the air filter annually, change tires/chains/sprockets/brakes when worn out. An airplanes gutless for it size, coddled in use engine if that delicate, should be tossed in the garbage and replaced with a better design IMO.
By the way my planes engines all make TBO plus, my current plane is past TBO and flown on condition now, so did everyone I have owned. Yesterday we flew to 100 Mile House, landed, didn't do anything to it except throw on the control lock, and lock the door, then we walked into downtown and had lunch, shopped some, walked back to it, and the temperature was -6C, it had now sat for a few hours, I didn't hesitate to just start it right up, no need for preheating it. I bumped the throttle up to about 1000 rpm so it would warm up quicker, did my checks, at 1500 rpm i did mag checks and cycled the prop twice, radioed traffic and my intent, nothing but silence, i taxied the 100 feet to the runway, again radioed my intention to take off and again silence, so I just fire walled it and gone. I treat this 520 like this every year all year, and it is totally problem free. I don't hand prop it, or even own a cowl cover. You guys are going to have a heart attack due to stress if you keep worrying about nothing.
 
-6C is no big deal. I thought we were talking about cold. Continental recommends preheat when the engine is cold soaked below 20* F. 20* or above? Fair game. An engine shut off 2 hours earlier has a lot of retained heat, by the way.
 
In Alaska pilots generally dress like they'll be walking home. Depending on a heater is a recipe for pain.

As to 406 rescue? It depends where you live. In Alaska the Air Guard sends C-130s with parajumpers or Pave hawks, depending on the situation. CAP isn't the first responder.

How times have changed. I flew with the Polaris CAP in the 90s and 2000s and we were always the first responders. Apparently the 406 has changed that.

Those were great times, had a great fleet of aircraft to fly and super, super cheap. And of course if it was an actual mission or training, it was all free flight time.

Back then we had the Super Cub, 185s, Beavers, 172 and 182s and the glider club. Fun times.
 
I use a metal garden sprayer with RV anti freeze. The key to making it work is getting it warm so I put the metal tank on the stove for a few minutes. Works great. Stays warm for quite a while so driving to the plane is no big deal. No pink stains like you'll hear about from guys who've never used it. ;)
Thank you Stewart
I will try this. Sure would beat scraping frost with a credit card like I did Saturday morning.
 
-6C is no big deal. I thought we were talking about cold. Continental recommends preheat when the engine is cold soaked below 20* F. 20* or above? Fair game. An engine shut off 2 hours earlier has a lot of retained heat, by the way.

Agreed 100%, but some people would be telling me how abusive that is, and I should have packed my honda generator to plug it into, put on cowl covers etc.
Once flying becomes a lot of work instead of enjoyable, I will sell the plane and stop flying.
 
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