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winter ops - turning over the engine by hand?

flyboy1963

flyboy1963

Well Known Member
Mostly for all you guys who store outside in below freezing climates; is it good, bad, or neither to go out and turn the prop by hand between flights?
The old standard is to pull it thru a dozen blades, which allegedly puts some oil on things inside, but I don't know the internal oiling system of a Lyc as well as a small-block chevy.
Does this really help?...or only as a pre-start ritual? I can't imagine it causes detrimental wear, as it would be the same as the first few seconds of operation anyway.
any engine gurus have an opinion?
 
If you can't fly it, don't touch it!

Turning the engine only wipes oil off the cylinders and cam lobes.
The first few seconds of starting doesn't leave the bare cylinder walls exposed for weeks after wiping off the oil.
 
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Mel said:
If you can't fly it, don't touch it!
Turning the engine only wipes oil off the cylinders and cam lobes.
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Ditto. I'm no expert, but everything I've heard is that its either detrimental or at best neutral. The practice of turning the prop through before starting comes from radials, where you're looking for a hydraulic lock.
 
Pulling prop through

Mel is right, all the old wisdom is leave it alone until it's time to run it.
Fuel Inj engines, when primed, dump fuel behind the intake valve so they are ready to immediately draw fuel into the cylinders.

Carbs with 4 cylinder hand primer should work the same as FI.

Carbs with an accelerator pump but no primer, pump the throttle a couple times then pull the prop through at least 4 blades. That precharges the cylinders with fuel so when you crank, you'll get all cylinders firing to get a good roll over and start. Worked like a champ on my Long-EZ.
 
Preheat Helps

Also in my opinion some kind of preheat before starting is needed in temperatures below freezing. I have a Reiff system with cylinder bands and a sump heater. It works great.

Jim Sharkey
RV-6
 
Minimum temp for preheat

Actually, according to Lyc, preheating isn't required until 10 Deg F, except for the O-320 H series and O-360 E series, which is 20 Deg F.

Here is a good reference to cold weather engine operation:
http://www.lexingtonflyingclub.org/LycomingaTextronCompany-ColdWeatherOperations.pdf

According to Premier Aircraft Engines, oil pan strip heaters should only be used 2 hrs prior to flight, otherwise the warm moist conditions created by the heater if left on all the time, will destroy the engine.
 
Fogging oil

Anybody have opinion on using fogging oil like is used in marine applications for winterizing?
 
rv9av8tr said:
Actually, according to Lyc, preheating isn't required until 10 Deg F, except for the O-320 H series and O-360 E series, which is 20 Deg F.

Here is a good reference to cold weather engine operation:
http://www.lexingtonflyingclub.org/LycomingaTextronCompany-ColdWeatherOperations.pdf

According to Premier Aircraft Engines, oil pan strip heaters should only be used 2 hrs prior to flight, otherwise the warm moist conditions created by the heater if left on all the time, will destroy the engine.
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I've been using a Reif sump heater for ten years. The heater runs 24/7 from November to April and no engine damage has occurred. Lots of info on this subject in the archives so I won't elaborate any further in this thread.
 
Pre heat

All I was saying is that it sure starts easier, develops oil pressure and warms to operating temeprature sooner with preheat than without :)

Regular operation is probably a more significant factor in avoiding corrosion damage.

Jim Sharkey
 
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don't touch it?

Okay, I can see some rationale for that.
Back to the oil pump thing, does anyone know if you are pumping oil to beneficial areas?...which would of course, inhibit corrosioin etc.
Or do need 10+ psi before it moves through the passages to the bearings etc.?
 
The big problem here is....

flyboy1963 said:
Okay, I can see some rationale for that.
Back to the oil pump thing, does anyone know if you are pumping oil to beneficial areas?...which would of course, inhibit corrosion etc.
Or do need 10+ psi before it moves through the passages to the bearings etc.?
Click to expand...

Until the engine is running, there is NO oil getting to the cam lobes. They are oiled by "splash" only. And the cam lobes are the weak point on a Lycoming.
This is of course assuming you don't have the aftermarket "ney nozzles".
 
Hi Perry.

The cylinders are oiled by the spinning crankshaft's oil that oozes out between the rods and side faces of the crankshaft.

The rods and crankshaft main bearings and cam bearings all have oil passages drilled in the case, with outlets at each main bearing and from there, is a passage in the crankshaft, to a rod bearing, both which are oiled under pressure.

When you turn the prop by hand, as Mel and others have pointed out, you only wipe away the film on the cylinders, leaving them dry, only to have a lot of friction and wear, during cranking the next time, until the pressure builds and they're lubricated by oil splash. Incidentally, the reason the Reiff heater is so valuable...cold oil ( around 30 degrees), doesn't "splash" very well but the Reiff heated oil at 85+ degrees is much more fluid and oils the cylinders almost instantly as the engine starts...one reason I had Reiff heaters on both my -6 and now my -10.

You can't spin the prop fast enough by hand to "splash" lubricate the cylinders...the reason you're advised to not rotate the prop, nor can you spin it fast enough to create oil pressure by hand. The bearings and rods will stay "wet" with oil for a very long time sitting still.

Best,
 
Frequent (undefined) flying is supposedly best.

I use an engine drier (dessicant) system and have started using Camguard.
 
49clipper

Never turn the engine over if you plane on not flying for a while. It removes all the oil from the parts and leaves it to rust. Shut if off and leave it alone.
 
All the old wisdom here is quite valid, but for one thing: Pulling the prop through will not "wipe off the oil and leave the surfaces dry". You only need a microscopic layer of oil to provide a lubricated bearing surface, and oil sticks quite well to the surfaces in our engines. Even after sitting for many months, there is still an oily film on all the oiled surfaces, and moving parts along them just redistributes that thin layer. Pulling the prop through by hand will not hurt anything, if anything it may redistribute oil that has pooled in crevices or on horizontal surfaces.

However: Starting the engine, and only running it for a few minutes "to redistribute the oil" and then shutting it down again (which makes me cringe every time I see it happen, every winter at my home airport) will bring moisture into the oil which does not get evaporated off because nobody ever runs their engine long enough or hard enough to boil it off. The water in the oil will react and form acids that will eat away at the aluminum parts. That, you don't want. So don't be starting it unless you're going to fly it, and don't fly it unless it's going to be more than half an hour's flying time. You need at least that long to boil out the moisture in the oil.
 
don't touch......unless.....?

Pierre & Mel, I see why they call them 'Lycosaurus' with all the splash lubrication. Obviously I am not adding oil where I want to without full hot run of the engine. Ground running for extended periods I recall is not recommended due to poor airflow and uneven cooling of the cylinders.
That said, I also think Rob's view that just moving the pistons once up and down can't be all that detrimental, as oil HAS to be pooling in the bottom of the bores, and it may also keep the rings and guides from languishing in one spot too long.
Appreciate your thoughts everyone!
 
Quote from Lycoming Service Letter L180B

"Pulling engines through by hand when the aircraft is not run or flown for a week or so is not recommended. Pulling the engine through by hand prior to start or to minimize rust and corrosion does more harm than good. The cylinder walls, piston, rings, cam and cam follower only receive splash and vapor lubrication. When the prop is pulled through by hand, the rings wipe oil from cylinder walls. The cam load created by the valve train wipes oil off the cam and followers. After two or three times of pulling the engine through by hand without engine starts, the cylinders, cam and followers are left without a proper oil film. Starting engines without proper lubrication can cause scuffing and scoring of parts resulting in excessive wear."
 
Pulling engine through

Just as a reference point, here's the experience with our Pitts S-2A, 1981. Our check pilot recommended pulling through twenty blades before starting the Lycoming AEIO-360A1E (200 hp). His reason was to create some oil pressure and actually get oil to the front main bearing. Twenty quick blades did indeed create some pressure on the gauge. The front main bearing is under a lot of stress in the Pitts as we flew it due to high g maneuvers and especially the autorotations and gyroscopic figures such as snap rolls, torque rolls, flat spins and Lomcevaks with full power. These maneuvers actually yaw and pitch the airframe from the prop precession. I don't know how valid were his reasons, but when the engine was overhauled at about 1200 hours (to replace a crankshaft with cracked flange) the pistons and cylinders and cam lobes were all in fine shape, as were crank and cam bearings (more positively lubricated?). We also pulled our Commanche 260B through 5 or 10 blades before starting in Wisconsin temps down to 15 below. It always started - and without any pre-heat for many years. At overhaul at 2200 hours the engine met field overhaul specs for everything except the main crank and cam bearings, which were almost worn out. How this all reconciles with the discussion above is not clear, at least to me...... Bill
 
Bill Dicus said:
Just as a reference point, here's the experience with our Pitts S-2A, 1981. Our check pilot recommended pulling through twenty blades before starting the Lycoming AEIO-360A1E (200 hp). His reason was to create some oil pressure and actually get oil to the front main bearing. Twenty quick blades did indeed create some pressure on the gauge. The front main bearing is under a lot of stress in the Pitts as we flew it due to high g maneuvers and especially the autorotations and gyroscopic figures such as snap rolls, torque rolls, flat spins and Lomcevaks with full power. These maneuvers actually yaw and pitch the airframe from the prop precession. I don't know how valid were his reasons, but when the engine was overhauled at about 1200 hours (to replace a crankshaft with cracked flange) the pistons and cylinders and cam lobes were all in fine shape, as were crank and cam bearings (more positively lubricated?). We also pulled our Commanche 260B through 5 or 10 blades before starting in Wisconsin temps down to 15 below. It always started - and without any pre-heat for many years. At overhaul at 2200 hours the engine met field overhaul specs for everything except the main crank and cam bearings, which were almost worn out. How this all reconciles with the discussion above is not clear, at least to me...... Bill
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I'm curious about this too - pulling the prop through before starting in cold weather does seem to result in noticeably quicker starts. It would seem to me that spinning the prop with the starter would have pretty much the same effect on cylinder walls as turning it by hand.

The main down-side I've encountered when turning the prop by hand is a tendency to slip on the ice and fall on my a-- :(
 
It's really not bad for the engine to be pulled through before start, although it may not be the safest practice. What this started as was a discussion about pulling through between infrequent flights. I do know that if you have oily bores a good slug will lay in the bottom. When you pull through after sitting, it will push that up & fill the bottom spark plug, I don't know how much that matters. As others have said, keeping a film on the lobes & lifter faces is first in priority, I think.
 
Found a Lycoming Service Letter that describes the issues for Active and InActive aircraft:

Lycoming Service Letter 180

I also seem to recall an article by Sky-Ranch (although I could not locate it), that described hand turning an engine is helpful to lessen the likely hood of issues with sticking valves, lifters, pushrods, etc.

As a matter of technique, before I fly (usually once a week), I will pull the prop through a few times (backwards, aghast, oh the horror...no vacuum pump on my system) :)
 
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Alan Carroll said:
I'm curious about this too - pulling the prop through before starting in cold weather does seem to result in noticeably quicker starts. It would seem to me that spinning the prop with the starter would have pretty much the same effect on cylinder walls as turning it by hand.

The main down-side I've encountered when turning the prop by hand is a tendency to slip on the ice and fall on my a-- :(
Click to expand...

Affirm, in cold WX, if the engine has run recently, turning it a couple of blades by hand makes it much easier to start. Rudi

I think the main debate is about longer term storage and then turning the blades.
 
I've always used AVBLEND, the top end lubricant. I believe the stuff works.

And so does Reiff preheat....oil temp will be over 100F when the starter is engaged later this morning for a local patrol.
 
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