8GCBC wrote:

CamTom12 wrote:

Bagarre wrote:I just pull the prop thru a dozen or so times to break the oil film.

I'm not an expert by any means but I had heard this was worse than just cranking it cold. Something about scraping the oil film off of parts or something.

That's after preserving oils are run. Tape a note "Do not turn prop"!

Not great to do anytime the plane is going to sit again, but, yeah, especially if you've pickled an engine.

8GCBC wrote:

mtv wrote:
Ummmm, actually, no. In fact, all you're doing by pulling the prop through prior to a cold start is in fact scraping all the oil off the mating metal parts inside the engine, so that when you actually start the engine, you have lots of metal to metal contact.....not good. Which is also the reason they say not to move the prop once it's pickled....why scrape all the oil off mating parts?

So, you pull your engine through a few revolutions to "loosen it up" (which by the way, doesn't "loosen" anything), but that slow turning doesn't generate enough movement in your oil pump to actually move much oil. So, it's not like you're pre lubing the engine either.

Do not pull the engine through prior to engine start in cool conditions. Just get in the thing and start it. Simple, and the best approach.

MTV

First time this was explained to me. I can not believe that turning a propeller a few minutes before start up is going to remove enough oil? Where is all that oil going? Suddenly disappearing into air?

Nope. Don't believe it's bad.

Ever look inside an engine? There are a LOT of parts with mating surfaces, like camshaft and lifters for example, or crankshaft and bearings, or piston rings and cylinder walls, etc...... So, let's use the cylinder wall and piston ring as an example. As you turn the engine through by hand, the rings are scraping any residual oil that's on the cylinder walls off. Where is that oil going? Probably winding up in the space between the rings, but the point is, it's not where it SHOULD be: providing lubrication between the rings and the cylinder wall. Same for the camshaft and lifters.

If you START the engine, it takes a moment or two for the oil pump to push oil through all the galleys, etc. But, as SOON as that engine fires, splash oil is going EVERYwhere inside that engine. You seriously think turning an engine by hand splashes any oil to critical parts?

The lubricating system of these engines is designed to circulate oil under pressure and by splash oiling. When you turn an engine through by hand, you're not accomplishing either, and you're scraping oil off vital mating parts.

It's called physics.

MTV

mtv wrote:

8GCBC wrote:

mtv wrote:
Ummmm, actually, no. In fact, all you're doing by pulling the prop through prior to a cold start is in fact scraping all the oil off the mating metal parts inside the engine, so that when you actually start the engine, you have lots of metal to metal contact.....not good. Which is also the reason they say not to move the prop once it's pickled....why scrape all the oil off mating parts?

So, you pull your engine through a few revolutions to "loosen it up" (which by the way, doesn't "loosen" anything), but that slow turning doesn't generate enough movement in your oil pump to actually move much oil. So, it's not like you're pre lubing the engine either.

Do not pull the engine through prior to engine start in cool conditions. Just get in the thing and start it. Simple, and the best approach.

MTV

First time this was explained to me. I can not believe that turning a propeller a few minutes before start up is going to remove enough oil? Where is all that oil going? Suddenly disappearing into air?

Nope. Don't believe it's bad.

Ever look inside an engine? There are a LOT of parts with mating surfaces, like camshaft and lifters for example, or crankshaft and bearings, or piston rings and cylinder walls, etc...... So, let's use the cylinder wall and piston ring as an example. As you turn the engine through by hand, the rings are scraping any residual oil that's on the cylinder walls off. Where is that oil going? Probably winding up in the space between the rings, but the point is, it's not where it SHOULD be: providing lubrication between the rings and the cylinder wall. Same for the camshaft and lifters.

If you START the engine, it takes a moment or two for the oil pump to push oil through all the galleys, etc. But, as SOON as that engine fires, splash oil is going EVERYwhere inside that engine. You seriously think turning an engine by hand splashes any oil to critical parts?

The lubricating system of these engines is designed to circulate oil under pressure and by splash oiling. When you turn an engine through by hand, you're not accomplishing either, and you're scraping oil off vital mating parts.

It's called physics.

MTV

Mike, patronizing me seems to be a pass time with you.

Turning a prop and starting the engine does not hurt anything. Is there any published information to convince me?

Never read or heard of what you are saying? Thank you for the response, I enjoy your discussion. But, I think I may win this one!

I'm not patronizing you. So, here's some information for you: Take a look at Lycoming Key Reprints, here: http://11hc.44rf.com/manuals/engine-pro ... prints.pdf

A discussion of cold weather operations starts on page 47 of this document. Please point out to me where in those recommendations that it suggests that pulling the propeller through prior to start is a good practice.

Now, please read the POH for your Scout, and quote for me any recommendation from that document that pulling the prop through prior to start is a good practice.

Or, please find ANY document from a manufacturer of an engine (other than a radial engine, see below) or an airframe that suggests that pulling an engine through prior to start is a good idea.

There is one case where this is commonly done: Prior to starting a newly overhauled engine for the first time. BUT, this is typically done after first pressurizing the lubricating system, ie: Pre Oiling the engine. That's a different deal.

I suspect that this notion that pulling an engine through prior to start is a leftover from the radial engine days. Radial engines all have cylinders which are inverted. There is a possibility for oil from the case to leak past the rings on one of these cylinders and wind up in the combustion chamber of one of these lower cylinders. This is called a "hydraulic lock". In physics 101, we learned that liquids are essentially not compressible. In this case, and if there's enough oil in one cylinder, and you punch the starter button without checking for this condition, you are probably going to bend something VERY essential, and seriously damage that engine when that piston comes up to TDC and tries to compress that oil.

So, with radial engines, it's generally good practice to pull the engine through slowly by hand to verify that there are no hydraulic locks in the engine. In this case, the risk of metal to metal contact causing damage is much less than the risk of a hydraulic lock, which will result in serious damage to that engine, right now.

But, I'm open to information.....just provide me ANY recommendations from a manufacturer of engines or airframes that recommends pulling an engine through prior to start......

MTV

8GCBC wrote:
Turning a prop and starting the engine does not hurt anything. Is there any published information to convince me?

Never read or heard of what you are saying? Thank you for the response, I enjoy your discussion. But, I think I may win this one!

I understand it's been documented. Mike Busch agreed with MTV, at least.

Imagine you've poured a little oil on a very smooth steel surface. Now you scrape it off with about 5-10 times with the backside of a filleting knife - that's basically what the rings are doing inside the cylinders when you hand-turn the engine.
Sure - the rings don't remove every last drop of oil - but you can imagine by the last scrape you get a lot more metal-metal contact than on the first. Now imagine turning the steel surface upside down and doing the same thing - very little oil would remain at the top of the cylinder. It needs splashed sump oil to keep it lubricated with each stroke.

P.S. Why warming the oil alone isn't really enough:
http://www.avweb.com/news/maint/182846-1.html

Mike... Looking at info you posted. Thank you. I appreciate the link.

Not to be an antagonist, just of me think...

...turning the prop to check "Propeller play", break ice, check compression etc...is so trivial. The velocity of the gears and joints is very minor. The oil film is not going away after 720 degrees (4 cylinder) of rotation. I say if you feel like turning the prop for a reasonable reason during preflighting it's OK.

Reading your link now ...

Battson wrote:

8GCBC wrote:
Turning a prop and starting the engine does not hurt anything. Is there any published information to convince me?

Never read or heard of what you are saying? Thank you for the response, I enjoy your discussion. But, I think I may win this one!

I understand it's been documented. Mike Busch agreed with MTV, at least.

Imagine you've poured a little oil on a very smooth steel surface. Now you scrape it off with about 5-10 times with the backside of a filleting knife - that's basically what the rings are doing inside the cylinders when you hand-turn the engine.
Sure - the rings don't remove every last drop of oil - but you can imagine by the last scrape you get a lot more metal-metal contact than on the first. Now imagine turning the steel surface upside down and doing the same thing - very little oil would remain at the top of the cylinder. It needs splashed sump oil to keep it lubricated with each stroke.

P.S. Why warming the oil alone isn't really enough:
http://www.avweb.com/news/maint/182846-1.html

That's interesting but ....

Ba ha ha ha, NJ is "very cold".

We often get sub zero FAHRENHEIT temps all throughout winter, when it's so cold it makes your brand new battery seem like a old half beat unit, when your split weight oil looks more like tar, I doubt that NJ club even knows what pour point is, or a whistle slot is.


Pre heat is not a old wives tale

8GCBC wrote:...turning the prop to check "Propeller play", break ice, check compression etc...is so trivial. The velocity of the gears and joints is very minor. The oil film is not going away after 720 degrees (4 cylinder) of rotation. ...

I agree. A few years back, I had a combination of a worn starter and a weak battery on my C150/150TD, I discovered that turning the cold engine through a few blades before cranking made it easier for the starter to do it's job. Dunno if it was "breaking the friction" or just what, but it worked, and I doubt it hurt the engine.

hotrod180 wrote:

8GCBC wrote:...turning the prop to check "Propeller play", break ice, check compression etc...is so trivial. The velocity of the gears and joints is very minor. The oil film is not going away after 720 degrees (4 cylinder) of rotation. ...

I agree. A few years back, I had a combination of a worn starter and a weak battery on my C150/150TD, I discovered that turning the cold engine through a few blades before cranking made it easier for the starter to do it's job. Dunno if it was "breaking the friction" or just what, but it worked, and I doubt it hurt the engine.

Turning a prop and starting an engine with full oil is OK...

Hell, Lycoming says mechanics can spin the engine with the freeking starter with no oil in the lines. We do this all the time after overhaul.. Busch says it will add 500 hours

If anyone is paranoid about this please read SI:

http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201241C%20(04-18-1997)/Pre-Oiling%20Engine%20Prior%20to%20Initial%20Start.pdf

8GCBC wrote:

hotrod180 wrote:

8GCBC wrote:...turning the prop to check "Propeller play", break ice, check compression etc...is so trivial. The velocity of the gears and joints is very minor. The oil film is not going away after 720 degrees (4 cylinder) of rotation. ...

I agree. A few years back, I had a combination of a worn starter and a weak battery on my C150/150TD, I discovered that turning the cold engine through a few blades before cranking made it easier for the starter to do it's job. Dunno if it was "breaking the friction" or just what, but it worked, and I doubt it hurt the engine.

Turning a prop and starting an engine with full oil is OK...

Hell, Lycoming says mechanics can spin the engine with the freeking starter with no oil in the lines. We do this all the time after overhaul.. Busch says it will add 500 hours

If anyone is paranoid about this please read SI:

http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201241C%20(04-18-1997)/Pre-Oiling%20Engine%20Prior%20to%20Initial%20Start.pdf

That Service Instruction describes pre-oiling a new or rebuilt engine after major maintenance. NOT every day flying activity. Here's the quote:

TIME OF COMPLIANCE: Prior to initial start after engine change, overhaul, oil cooler replacement or draining or any prolonged period of inactivity
To avoid possible high speed bearing failure resulting from lack of lubrication during initial starts all
aircraft engines should be preoiled prior to first start.

Of course you want an engine pre-oiled prior to an initial start. But this has nothing to do with a pilot pulling a prop through prior to every start as a routine matter. For one thing, a newly rebuilt engine doesn't have any oil to scrape off the cylinder walls.....

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

mtv wrote:
Hell, Lycoming says mechanics can spin the engine with the freeking starter with no oil in the lines. We do this

TIME OF COMPLIANCE: Prior to initial start after engine change, overhaul, oil cooler replacement or draining or any prolonged period of inactivity
To avoid possible high speed bearing failure resulting from lack of lubrication during initial starts all
aircraft engines should be preoiled prior to first start.

Of course you want an engine pre-oiled prior to an initial start. But this has nothing to do with a pilot pulling a prop through prior to every start as a routine matter. For one thing, a newly rebuilt engine doesn't have any oil to scrape off the cylinder walls.....

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

It's so so trivial nobody except you is afraid to turn the prop! That's it. Get over it! Not going to hurt it!

Newly built engines are covered in grease and oil from assembly. BTW.

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

I used to pull the prop through on my T-6 before starting, never had issues, in fact the Flight Manual from NAA said to pull the prop through several blades. ...8 pages yet?

AKJurnee 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

I used to pull the prop through on my T-6 before starting, never had issues, in fact the Flight Manual from NAA said to pull the prop through several blades. ...8 pages yet?

The T-6 is equipped with a radial engine.....you're preventing hydraulic lock. Has nothing to do with flat engines.

MTV

8GCBC wrote:Turning a prop and starting an engine with full oil is OK...

Hell, Lycoming says mechanics can spin the engine with the freeking starter with no oil in the lines. We do this all the time after overhaul.. Busch says it will add 500 hours

If anyone is paranoid about this please read SI:

http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201241C%20(04-18-1997)/Pre-Oiling%20Engine%20Prior%20to%20Initial%20Start.pdf

Sorry - I think that's a little off topic.

That doesn't mention the engine and oil being at -30*F. In fact you usually pre-oil with pre-heated oil, I've done it myself. Come back to the thread title. Context is everything.

Oil at room temperature and oil which is almost frozen have totally different viscosities and behave totally differently. One is sticky and flows readily, the other is almost a pseudo-plastic fluid with very high surface tension.

Battson wrote:

8GCBC wrote:Turning a prop and starting an engine with full oil is OK...

Hell, Lycoming says mechanics can spin the engine with the freeking starter with no oil in the lines. We do this all the time after overhaul.. Busch says it will add 500 hours

If anyone is paranoid about this please read SI:

http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201241C%20(04-18-1997)/Pre-Oiling%20Engine%20Prior%20to%20Initial%20Start.pdf

Sorry - I think that's a little off topic.

That doesn't mention the engine and oil being at -30*F. In fact you usually pre-oil with pre-heated oil, I've done it myself. Come back to the thread title. Context is everything.

Oil at room temperature and oil which is almost frozen have totally different viscosities and behave totally differently. One is sticky and flows readily, the other is almost a pseudo-plastic fluid with very high surface tension.

Yes Sir. I shall immediately consult your chain of command for further instruction on how to use the Internet. . And shall never turn another prop in fear of this.

mtv wrote:
Or, please find ANY document from a manufacturer of an engine (other than a radial engine, see below) or an airframe that suggests that pulling an engine through prior to start is a good idea.

Mike,

My 1956 Cessna 180 manual clearly states in the pre-flight if conditions are cold to pull through 2 times.

See step 11:

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.

This is all getting a bit trivial. I tend to doubt that it makes much difference one way or the other whether the prop is pulled through a couple revolutions, although as I said earlier, I much prefer to preheat than to do what appears to stress the machinery unnecessarily by starting a cold-soaked engine.

I've hand-propped different airplanes, but that's intentional for starting, not for "limbering up". The biggest reason that I don't pull my prop through before starting the engine is that I've seen/read of events where the engine fired unexpectedly when the prop was pulled through. Here's an example I just saw recently:

Just making sure the key or switches are off and the mixture is at idle cut-off isn't necessarily going to prevent it, so I choose not to do it. Part of my passenger preflight is to emphasize how dangerous the prop is and to always treat it as if it could start moving at any time. I think that's good advice for pilots to remember, too.

Cary

My Scout is "One Owner" I don't pull on the prop much to feel the compression or gears. I known her well she's a good girl.

But, I have been around aircraft in which turning and inspecting the prop saved my life. If there is any question about the compressing, values, prop blades ...pull it thru! Anybody here had a blade loose? It happens and it may kill somebody.

But, yes I do not do it everyday. le checking sumps, when there is a unknown variable like getting "New" fuel I do.

There is no right or wrong. But, it will not hurt an engine or screwup the lubracation if you just start it! If you leave it yeah, do not turn the prop (I tape a note too).

Just be freeking careful around props anytime and do not trust anyone with the switches!