Also, from the Operating Details section of both the 1953 & 1957 C180 owner's manual :
"Prior to starting on cold mornings, it is advisable to pull the propeller through several times by hand to "break loose" or "limber" the oil, thus conserving battery energy."

Bottom line is:

If it's cold, preheat your engine and gyros. The colder it is, the longer you want them to heat-soak.

Then, everything else is just a moot point.

Gump

hotrod180 wrote:Also, from the Operating Details section of both the 1953 & 1957 C180 owner's manual :
"Prior to starting on cold mornings, it is advisable to pull the propeller through several times by hand to "break loose" or "limber" the oil, thus conserving battery energy."

Are these are the same manuals that advise running 50 deg ROP? Just curious.

CamTom12 wrote:

hotrod180 wrote:Also, from the Operating Details section of both the 1953 & 1957 C180 owner's manual : "Prior to starting on cold mornings, it is advisable to pull the propeller through several times by hand to "break loose" or "limber" the oil, thus conserving battery energy."

Are these are the same manuals that advise running 50 deg ROP? Just curious.

From the operating details:
"Mixture leaning is accomplished as follows: pull mixture control out until airspeed starts to drop or engine becomes rough; then enrichen mixture slightly beyond this point. Any change in altitude, power, or carburetor heat will require a change in lean mixture setting. Do not lean mixture with power setting above 23 inches of manifold pressure and 2450 rpm."

FWIW 23" / 2450 is listed as about 76% power. And re LOP ops, remember these airplanes were produced prior to fancy engine monitors or even multi-point CHT / EGT gauges. Standard heat instrumentation was a CHT gauge and an oil temp gauge, both mainly used to determine any need for opening the cowl flaps and/or lowering the climb angle.

Ok, thanks. I was curious because I'd heard some of the old manuals called for 50 deg ROP, which is a dangerous place to run at higher power settings. I hadn't seen any myself and since you were in the manual I figured I'd ask to see if this one did. Not because of any LOP ops questions.

Near as I can tell, all this LOP / ROP leaning advice has come about after they quit producing C180's in 1981. IMHO you definitely need multi-point CHT/EGT instrumentation, and I'm not sure how good a technique LOP is to carbureted engines anyway, with their wide cyl-to-cyl temp spreads. I pretty much lean mine just like the owner's manual says. Old school airplane, old school pilot, old school techniques.

hotrod180 wrote:Near as I can tell, all this LOP / ROP leaning advice has come about after they quit producing C180's in 1981. IMHO you definitely need multi-point CHT/EGT instrumentation, and I'm not sure how good a technique LOP is to carbureted engines anyway, with their wide cyl-to-cyl temp spreads. I pretty much lean mine just like the owner's manual says. Old school airplane, old school pilot, old school techniques.

Yeah, I hear you. Curiosity on my part.

On LOP with carbed engines, I managed it the other day on my O-320. Took part throttle and full carb heat but ran pretty good. EGTs were pretty close, though I'm still dealing with #3 CHT being about 50 deg higher than the others. Nice and cool at 350 deg, 300 deg CHTs on 1,2, and 4.

Sorry about the thread drift!

Interesting article in the recent Kitplanes magazine about oils. It also mentions why a person should preheat in cooler temps with the point being made about how oil 'flows' due to its vescosity at different temps. Can't recall its exact wording but suggested one should preheat.

hotrod180 wrote:

mtv wrote:...Again, show me something, anything, that is written by a manufacturer of airplane or engine which suggests that turning a prop through by hand is a good idea or even an okay procedure prior to start.
MTV

Looks like Soy just did. That's exactly what several people have been referring to in posts on this thread.
Now, it's your turn-- show us some engine manufacturer's instructions that say it's not OK.

Still waiting...

Out of 1959 Cessna POH:

By "cold" do they mean 30F above zero, or 30F below zero?

I'd spin a prop around all day long at 30 above without a second thought. 30 below, I ain't touching anything till it's warm.

Gump

Skalywag wrote:Out of 1959 Cessna POH:

I so so so paranoid around props! Never will trust anyone with switches.

My hangar mate had an old Cessna 421 (jump door installed for Dillingham AAF). The pilot pushed the C421 into the hanagar and started to turn the prop. "Bang" a freaking cylinder fired. The jump pilot forgot the mags! Never forget that!

Good to do a magneto grounding check at 100s and or annuals if not daily

Gump,

The POH doesn't give specific temps for what they refer to as cold weather. It says is that if aircraft is to be operated consistently below 20f the Cessna winterization kit should be installed. Says kit includes an oil cooler shutter, a shutter control, oil cooler cover plate, intake manifold cross-over tube cover and carburetor air intake restrictor cover. Also goes into detail about proper use of oil dilution system.

All antique info for the most part. Those winter baffle kits are dangerous in my opinion. -30 on the ground translates to +10 at 1000 feet due to inversion layers. Then you're cooking cylinders and disrupting airflow in the cowling.

Oil dilution, that translates to dumping gasoline in the oil to thin it so it'll flow when it's extremely cold. That does nothing to address the issues with bearing clearances and metal on metal associated with cold soaked engines.

I've never seen an airplane with the oil dilution system actually used. And none of us up north that I flew with would ever use the winter baffles.

Again... Pre-heat if it's below 30F.

GumpAir wrote:All antique info for the most part. Those winter baffle kits are dangerous in my opinion. -30 on the ground translates to +10 at 1000 feet due to inversion layers. Then you're cooking cylinders and disrupting airflow in the cowling.

Oil dilution, that translates to dumping gasoline in the oil to thin it so it'll flow when it's extremely cold. That does nothing to address the issues with bearing clearances and metal on metal associated with cold soaked engines.

I've never seen an airplane with the oil dilution system actually used. And none of us up north that I flew with would ever use the winter baffles.

Again... Pre-heat if it's below 30F.

It just goes to show the instructions (and POHs above) written in the 1960's are not perfect.
If I think about other stuff happening in the 1960s - like smoking on planes, not installing seat belts in cars, drink driving all being legal, and commercial aviation being 50 times more dangerous than today - it was a different time
You can just imagine the sentiment - "Cold? It'll be grand - just pull the engine through a couple of times, it will start without flattening battery". No bad things happened immediately, so it seemed like a good idea. To some extent, they were right.

Lets look at a modern POH from a Cirrus SR22 - remembering this is using the same 1960's vintage engine with the same incumbent operations manuals. They say:
If the engine is cold (i.e. not warm) then it is recommended to pull it through a few times - they explicitly say this is done to save the battery.
If the engine is frozen (20*F) then preheating the engine is recommended - they explicitly say failure to preheat could "result in internal damage to the engine".
An important distinction there, it's all about how cold the engine is.

With the benefit of a modern scientific understanding what happens to equipment in the cold, there are a bunch of guys who've actually written about this stuff recently - and preheating is unarguably the way to go in their professional opinion too:
http://www.aopa.org/News-and-Video/All-News/2014/March/10/Aircraft-maintenance-Proper-engine-preheating
http://www.avweb.com/news/maint/182846-1.html#bearings

Don't get me wrong. We spend minutes pulling my prop through at annual doing compressions / timing etc with a warm engine, like everyone else. No chance that does any damage But when its been covered in frost all night, personally I prefer to avoid it because I want my expensive engine to last as long as possible. I don't operate my plane in those temperatures more than a dozen times a year, but if I did that all winter - I would be preheating overnight or for a few hours at least in the morning. I already preheat as it is, if possible.
That's my 2c, and YMMV.

I don't think anyone here believes pulling the prop through on a very cold morning does immediate damage. Your battery will thank you for it. But I think we can all agree that the bearings won't thank you for it, and over time the experts believe that does do cumulative damage.
I think we can all agree that preheating is a better decision, if you have the choice and want your engine to last as long as possible.

Posted that POH clip per MTV's request for documentation. It's obvious where pilots get the pull the prop through when cold thing, from the POH, antique info nonetheless.

My personal practices are to pre-heat below 45 degrees minimum temp, it'd have to be an emergency to try n start if it's freezing. These engines are crazy expensive! Any day it's below 55 or so usually plug in the oil sump heater for an hour, or as long as it takes to drink couple cups of coffee, mostly not to have to ground run longer than necessary to get oil up to operating temps.

Started both 0-470 and 0-320 in the mid-upper 30's. The 470 is usually a bitch to start at those temps and runs really rough at first, the 320 starts much easier and smoother. Both get 20W50 oil in the winter.

Skalywag wrote:My personal practices are to pre-heat below 45 degrees minimum temp, it'd have to be an emergency to try n start if it's freezing. These engines are crazy expensive! Any day it's below 55 or so usually plug in the oil sump heater for an hour, or as long as it takes to drink couple cups of coffee, mostly not to have to ground run longer than necessary to get oil up to operating temps.

Started both 0-470 and 0-320 in the mid-upper 30's. The 470 is usually a bitch to start at those temps and runs really rough at first, the 320 starts much easier and smoother. Both get 20W50 oil in the winter.

I hear you loud and clear. That's pretty much exactly what I like to do, too.

I (usually, not always) pre heat anytime under 50F in Oregon. With a little 0.040 SS wire I can even use a cheap WalMart heater $10.00. Gives me time to drink my coffee at the hangar.

My take is that the "limbering up the oil by turning through the prop" issue was a separate topic than the pre-heating issue. It was postulated that turning the prop a couple blades as part of the pre-start procedure was a strict no-no, with no mention of extreme cold temps or not. My post along with others was in response to that concept.

I believe in pre-heating if it's down below freezing, but I think in mid-thirties temps it's optional- esp if you're running multigrade oil. It gets below freezing here in the sea-level Puget Sound area fairly often in the winter, but I don't think its ever gotten below freezing inside my hangar. I still to pre-heat for an hour or so when it's that cold outside though.

Reading back through this thread, I was remembering how we handled things back in olden times. 40 years ago, built-on preheaters didn't exist, and using salamander heaters was mightily inconvenient, if we could start without them. At a friend's request, I did this little write-up of how we used to start an O-470 in the cold:

I was pards in a 1970 model Skylane from 1974 until 1978, when we traded it in for a TR182. Also I did quite a few flights SE charter in mid-70s era Skylanes, and my IR training was all in a 73. This was before anyone was smart enough to have a built-in (or on) engine heater.

In ultra-cold weather (below 0F), we'd have the FBO use the salamander heater on it for an hour, then use the "really cold weather" method next.

In really cold weather (like 0-30F), we'd use 4 shots of prime, then leave the primer out. Full rich. Half an inch of throttle. When starting to crank, shove the throttle in all the way. As soon as it would fire (which it would do right away), pull the throttle back to the half inch mark again, slowly push the primer in. When the temp was close to zero, it might be necessary to give it another shot of prime to keep it running.

In not-so-cold weather (30-40F), 3 shots of prime, then leave the primer out. Full Rich, half inch of throttle. Again shove the throttle in all the way, then it would fire, pull the throttle back to half inch, slowly push primer in.

I'd never found it necessary to actually pump the throttle more than the one shove.

All that assumed that the timing had been set correctly and the plugs were in good shape. Then we'd have to sit idling for a bit with the avionics on before the tubes would all warm up so that the radios would work. By the time the radios would work, the engine was warm enough to fly.

In ultra cold weather, it was often necessary to fly with the carb heat out in order for the engine to run smoothly (a little trick I learned when I was a student in Alaska).

In all the time I regularly flew Skylanes, I had trouble starting ours just once, and it was because the battery needed to be replaced.

The primer only worked on a couple cylinders--that's why the one shove of the throttle helped the engine to start. The danger of pumping the throttle (especially if you do it without cranking) is that you are spraying gas all over the place, so it's easier to start a fire that way.

Today I wouldn't think of trying to start any aircraft engine at near 0F temps without preheating it in some fashion, not just long enough for it to start, but long enough for it to actually warm the engine. Built-on heaters like Reiff and Tanis have made a big difference in the convenience of preheating, and as little as they cost compared to the cost of an engine, they're really good investments.

Cary