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As requested here, here are the sections from my POH about turning the engine over by hand as an aid to starting on cold days...



Lycoming O-320 E2G if that makes a difference.

I guess it's a new year, and I haven't seen this topic for a while, so have at it :D
I do turn my prop through 4 blades on cold days, particularly if not flown for a week or so, if I remember.

If I forget, it doesn't seem to make much difference.

On the other hand, there is cold and cold. In the UK we rarely get flyable days with extremely cold (in world aviation terms) type weather.
PaulSS wrote:And, of course, unless you checked the oil level after shutting down on the previous flight, you'll have to 'pull through' your Rotax quite a few times to 'burp' the engine and get the oil into the can so the quantity can be checked.

Strictly speaking, only if the dip stick indicates a low oil level. :wink:

That said I would rather pull it though prior to starting than after a flight when the oil is less viscous and it is an unknown time until he next flight. :D
Flying_john wrote:It is not a recommendation by Lycoming to pull through before starting as it scrapes away any remaining oil film on bearing surfaces and inside of cylinders before oil pump is able to re-supply oil.

I've heard this assertion quite a few times over the years.

Do you have a Lycoming-sourced citation for this?
There may be some confusion(all mine, no doubt!) about pulling through by hand before starting, and pulling through by hand during periods of layoff (for example during the winter) where the engine is not to be started.

I subscribe to the former, but not the latter.

When TopCat first mentioned this (on the other thread at the top of the page) I had incorrectly assumed that TopCat was referring to the latter.

The extract from the aircraft POH made clear to me that pulling through before a start was what was meant (and I agree, as has been supported by some subsequent posts, but not all).

But Flying_john 's post raises the same question: where do Lycoming say that? Or is this the same confusion? The Lycoming engine O-145 does not have a starter.

The Lycoming operator’s manual for the O320 says:

4. COLD WEATHER STARTING. During extreme cold weather, it may be necessary to preheat the engine and oil before starting.

It doesn’t mention pulling the prop through before starting, but neither does it state not to do it!
Lycoming Service Letter No. 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.
TopCat, Edward Hawkins liked this
Lycoming obviously knows best but I cannot understand the logic of that if you start immediately after pulling the blades trough.
mick w, Rob L liked this
Lycoming does not obviously know best. They can't even make a camshaft that doesn't wear away like it were marshmallow.

If the primer pumps directly into the cylinders then there's not much point in pulling through - unless cylinder priming doesn't actually help and you have to pull through to get something into the manifold from the carb. But then you probably won't get much out of the carb just by pulling through, so you either need a primer that primes into the manifold or a few pumps on the throttle.

My C90 routine is four pumps of prime, pull through four blades, two pumps of throttle then mags hot, throttle 1/4" open and swing the prop. It usually always works, but I can't be sure that every step is essential. I have not the time nor the inclination to try different things to work out exactly which parts makes it go and which part is superfluous (the pull-through?). A pure scientist would, be he or she is probably less keen to go flying and happy to spend a few hours experimenting with starting routines.