Pulling the Prop through by Hand

Fearless Tower said:
Just to be clear, I'm only saying that you should never rotate a radial engine backwards.
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Why. Ive been around the Radial engines most all of my life, and have never heard they can't be turned backwards.

If they can't be turned backwards why how can you take out the backlash of the gear train to time one?
 
Clark1961 said:
Not to be a spoilsport or nothing but would you 'splain to me how aircraft oil and auto oil are/aren't the same?
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Auto oils are allowed to have metallic additives such as sulphur.

Aircraft oil can not contain any metallic additives because they are required to be ash less. metallic additives cause a glowing ash in the combustion chamber that will cause preignition. yes your car will run great on Phillips 20W50 or any other aviation oil.

Rotax what's that?
 
Tom-D said:
Why. Ive been around the Radial engines most all of my life, and have never heard they can't be turned backwards.

If they can't be turned backwards why how can you take out the backlash of the gear train to time one?
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From what I understand, the issue with pulling the prop backwards is not that it causes damage by itself, but that it is an ineffective method of clearing a hydraulic lock. It causes the oil that is creating the lock condition to go from the cylinder into the intake manifold. From there, the oil will get sucked back into the cylinder when the engine is started, where it can re-establish the hydraulic lock and damage the engine.

http://www.avweb.com/news/pilotlounge/182680-1.html
 
Tom-D said:
Why. Ive been around the Radial engines most all of my life, and have never heard they can't be turned backwards.



If they can't be turned backwards why how can you take out the backlash of the gear train to time one?
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Really Tom?

Your ignorance…or perhaps more accurately, argumentativeness is showing.

Try here for starters…

From: http://www.radialengines.com/frequently-asked-questions/
Q. Do I always need to pull my engine through before start up?

A. Only if you want to avoid liquid locks. By gravity oil is drawn into the lower cylinders. If the oil level in the combustion chamber is so great that the piston contacts it, something is going to give, and it will not be the oil. Pulling the engine backwards will often clear the combustion chamber of oil, but will only transfer the oil to the intake pipe where it can again be drawn into the combustion chamber and cause a liquid lock. If, as you pull the engine through, a liquid lock is suspected, the only safe recourse is to remove the lower front spark plugs and drain whatever oil if found there. It is a small price to pay for getting to fly behind a radial engine.
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More here: http://www.radialengines.com/wp-content/uploads/2012/06/AVOIDING_ENGINE_LIQUID_LOCKS.pdf
 
Tom-D said:
Auto oils are allowed to have metallic additives such as sulphur.

Aircraft oil can not contain any metallic additives because they are required to be ash less. metallic additives cause a glowing ash in the combustion chamber that will cause preignition. yes your car will run great on Phillips 20W50 or any other aviation oil.

Rotax what's that?
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Ashless is part of it. There's another piece that hasn't been described yet and it's material in corrosion prevention. Automotive oils tend to wet surfaces, aviation oils tend not to be wetting.

Rotax is on of them there snow machine engines that runs too faaast and burns motorcycle earl. (not)
 
Palmpilot said:
From what I understand, the issue with pulling the prop backwards is not that it causes damage by itself, but that it is an ineffective method of clearing a hydraulic lock. It causes the oil that is creating the lock condition to go from the cylinder into the intake manifold. From there, the oil will get sucked back into the cylinder when the engine is started, where it can re-establish the hydraulic lock and damage the engine.

http://www.avweb.com/news/pilotlounge/182680-1.html
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Clearing hydraulic locked cylinders is a totally different subject.
 
Fearless Tower said:
Really Tom?

Your ignorance…or perhaps more accurately, argumentativeness is showing.

Try here for starters…

From: http://www.radialengines.com/frequently-asked-questions/


More here: http://www.radialengines.com/wp-content/uploads/2012/06/AVOIDING_ENGINE_LIQUID_LOCKS.pdf
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Yes really, radial engines can be turned backwards, but as noted it does no good when trying to clear a hydraulic lock.

If they can't be turned backwards why do those in the know like the Curry brothers warn against it to clear cylinders?

The only proper method of clearing cylinders of oil is to pull the spark plugs and drain it.
 
Tom-D said:
Yes really, radial engines can be turned backwards, but as noted it does no good when trying to clear a hydraulic lock.



If they can't be turned backwards why do those in the know like the Curry brothers warn against it to clear cylinders?
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Back tracking Tom?

No one said they can't turn backwards. I (as did Curry) said they shouldn't be turned backwards....at least not by a pilot pulling the prop through prior to start.
 
Fearless Tower said:
Your ignorance…or perhaps more accurately, argumentativeness is showing.
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Is my willingness to correct the ignorance shown by you and other on this page is misconstrued as an argumentativeness.

There are a multitude of reasons to turn a radial engine opposite direction of normal rotation, clearing cylinders isn't one of them.
 
Fearless Tower said:
Back tracking Tom?

No one said they can't turn backwards. I (as did Curry) said they shouldn't be turned backwards....at least not by a pilot pulling the prop through prior to start.
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Did you forget what you wrote in post 7 of this thread?

It won't ruin your day. we do it all the time
 
Tom-D said:
Is my willingness to correct the ignorance shown by you and other on this page is misconstrued as an argumentativeness.



There are a multitude of reasons to turn a radial engine opposite direction of normal rotation, clearing cylinders isn't one of them.
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I have shown no ignorance- I have backed my position up with a reference that even you do nit disagree with. Ron has also backed his position up with a reference. Your basically saying the Shell doesn't know what they are talking about .

You aren't clearing up ANY ignorance here Tom. Just coming across like an argumentative fool....yet again. Just like you did with your Ricky Nelson freebase BS.

You are a knowledgeable A&P, who damages his own credibility simply for the sake of arguing with people.
 
Arguments may become contentious, but I have noticed that they often illuminate the issues in spite of that.
 
Tom-D said:
yes your car will run great on Phillips 20W50 or any other aviation oil.
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20W-50 is excessively heavy for most spark-ignition automotive engines (at least water cooled), even really old ones where owners try to stop leaks that way. You can spin bearings, and the dry start problem will be quite serious, especially in winter. Your owners manual has recommended oil viscosity. It's not likely to include 20W-50 unless it's a Diesel or a medium duty truck.

The additive package isn't the greatest but it won't damage a car quickly. It will eventually fill the catalytic converter with phosphates, which is why those have been cut back substantially in API SJ and later oils. For older vehicles with cheap cats, it's not a very good tradeoff as it shortens the life of the cam lobes.
 
MAKG1 said:
20W-50 is excessively heavy for most spark-ignition automotive engines (at least water cooled),
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It might be excessively viscous for that application (where 5W-30 or 10W-40 is more the norm), but I'll bet it's about 7.5 lb/gal heavy regardless of its viscosity rating. :wink2:
 
Fearless Tower said:
And where in that post did I say it 'can't' rotate backward?
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IOWs you didn't mean that you could not turn a radial engine backwards when you said Post 7

"Or a radial. That will ruin your day."

The conversation had not made the turn to hydraulic lock at that post..

I'm gone, arguing about what you said isn't worth my time.

I'm starting to realize why Bruce isn't here any more.
 
I always pulled the Stearman tru 6-8 times by hand clockwise. No problem. Used 50 wt shell. You see old movies and photos of ground crew doing the same on B 17s in England etc. I never turned it backwards, never had a reason to. Same with the 195 Cessna.
 
Fearless Tower said:
I have shown no ignorance- I have backed my position up with a reference that even you do nit disagree with. Ron has also backed his position up with a reference. Your basically saying the Shell doesn't know what they are talking about .

You aren't clearing up ANY ignorance here Tom. Just coming across like an argumentative fool....yet again. Just like you did with your Ricky Nelson freebase BS.

You are a knowledgeable A&P, who damages his own credibility simply for the sake of arguing with people.
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Ron's reference is aeroshell's advertising it is not the standard.

If you like to believe the marketing department of Shell over all the other oil manufacturers you go right ahead.

ECI has published " Oil Talk For Dummies" simply explaining what the Letters used in the industry really mean. If you choose to ignore them that's OK too. we A&P's love the work.

Just don't tell me I'm arguing when I give you a reference that you really shouldn't ignore.
 
Tom-D said:
Ron's reference is aeroshell's advertising it is not the standard.

If you like to believe the marketing department of Shell over all the other oil manufacturers you go right ahead.

ECI has published " Oil Talk For Dummies" simply explaining what the Letters used in the industry really mean.
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...even if Shell does otherwise? Is Shell not in the industry? And who made ECI the arbiter of what the oil industry standards are? They aren't even in that industry.

But yes, I was focusing on what the letters mean when encountered on the labels of Shell's products, since that's what the original question was asking.
 
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Ron Levy said:
...even if Shell does otherwise? Is Shell not in the industry? And who made ECI the arbiter of what the oil industry standards are? They aren't even in that industry.

But yes, I was focusing on what the letters mean when encountered on the labels of Shell's products, since that's what the original question was asking.
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When you have 10 marketers using the letters and number formula's and one who does not who is the maverick ?

ECI must believe the industry standard, or they would not include it in their methods of break in instructions, As who appointed them the experts in oil? Who appointed Shell's system of numbering, the proper way to label their products?
 
Tom-D said:
When you have 10 marketers using the letters and number formula's and one who does not who is the maverick ?
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And who's the 800-lb gorilla among the ten? I doubt you can find more than three aviation lube oils at any FBO in the country, and most of the bottles on the shelf will be Aeroshell. And if they only carry one aviation oil, you can bet it will be Aeroshell. So yeah, I'd have to say that when it comes to piston engine aviation oils, Aeroshell is the trend-setter and everyone else is on their own.
 
Tom-D said:
When you have 10 marketers using the letters and number formula's and one who does not who is the maverick ?

ECI must believe the industry standard, or they would not include it in their methods of break in instructions, As who appointed them the experts in oil? Who appointed Shell's system of numbering, the proper way to label their products?
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duplicate post
 
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Tom-D said:
When you have 10 marketers using the letters and number formula's and one who does not who is the maverick ?

ECI must believe the industry standard, or they would not include it in their methods of break in instructions, As who appointed them the experts in oil? Who appointed Shell's system of numbering, the proper way to label their products?
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Who makes the oil to SAE and MIL-spec standards? ECI or Shell?

Dan
 
Dan Thomas said:
Who makes the oil to SAE and MIL-spec standards? ECI or Shell?

Dan
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How many other companies make oil products? who is the only one that puts a "W" in front of the numbering system.

what's the chances that Shell screwed the labeling on the cans and are simply doing a CYA to cover the losses of not using the cans?
 
All this to-do over a single letter! :rofl:
 
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If I thought pulling a prop through by hand did anything different than pulling it through with the starter, I'd be taking the long sockets and a cheater bar out to the car every morning to crank it by hand too, before starting it.

Doesn't make any mechanical sense on most of our engines. Just start the stupid thing with the starter, and stop playing with the prop. A broken P-lead could kill you.

As far as the thing about carbon vane vacuum pumps... those vanes slide in and out like butter... they'll move back just fine if you must move the prop backward. And if they're tiny short pieces and the stupid pump is about to die anyway, might as well do it now on the ground, then in the soup in IMC ten minutes from now, if they're that worn. Or if they're that "sticky" because they're short, and they don't want to move backward. They're not that fragile inside of the recommended number of hours before you should pull the thing and replace it. Take them off the airplane at the recommended number of hours, and there will be plenty of vane left.
 
denverpilot said:
If I thought pulling a prop through by hand did anything different than pulling it through with the starter, I'd be taking the long sockets and a cheater bar out to the car every morning to crank it by hand too, before starting it.
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What it does differently is not sucking juice out of the battery for however many turns are done by hand. In the Cessna POH quoted in post #17, that was the reason given for recommending it for cold weather starts.
 
Palmpilot said:
What it does differently is not sucking juice out of the battery for however many turns are done by hand. In the Cessna POH quoted in post #17, that was the reason given for recommending it for cold weather starts.
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And no one can give any proof it makes any difference in that either.

But I was speaking of the OWTs that say it's somehow better for the *engine*. It isn't.

The battery will recharge. That's why we have batteries.
 
Best I can tell from my very limited knowledge base, this is something that has been carried over from radial engines where there is clearly are need to do this prior to a start.

As for whether or not turning the prop by hand a few times will loosen up the oil and reduce viscosity which would make for an easier start in the cold....I'm really unsure.

Again my very limited knowledge tells me that yes moving the oil would break it up and reduce viscosity by turning that kinetic energy into heat. However I seriously doubt turning the prop 4,5,6,7, even 8 times will make a significant difference here.

I'd like to see some research on the how viscosity is effected by stirring/motion. I will do some research on the topic.

Lastly, typically the POH is not wrong. It can certainly be wrong but I think we'd need some more reputable sources to determine whether it is wrong or not in this matter. Although if Lycoming is not recommending this there is a clear miscommunication somewhere and that ought to be cleared up. They are not saying that it shouldn't be done however. Nor have I seen any posts here that given good reason NOT to turn the prop by hand before starting.

That being said folks who think it does something: keep turning it because it won't be damaging the aircraft (AFAIK). Folks who think it does nothing: get in and start the airplane.

Things we can agree on:

Viscosity decreases with an increase in temperature.
Kinetic energy + Friction = Heat.

DISCLAIMER: THE POST ABOVE REFLECTS MY OPINION ON THE MATTER BASED ON MY VERY LIMITED KNOWLEDGE. I DO NOT MAKE ANY CLAIMS TO HAVE EXPERTISE IN THE FIELD OR TO BE A AIRCRAFT ENGINEER.
 
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From a non-engineer perspective...

...I think the main argument against is that you're dragging potentially unlubricated surfaces over one another without the benefit of oil pressure to keep them apart.

And that the best way to get oil pressure up is to just start the engine.

But I'm open to data/arguments from both sides.
 
Engine said:
Are you saying that when you crank the starter oil will be flowing immediately?
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No.

My mental image is that the oil pump must get up to a certain speed to supply appreciable oil pressure. That at very low speeds it cannot supply the pressure to keep metal surfaces apart.

But I can see the argument that "x" revolutions are required regardless to get pressure, and the speed of those revolutions is unimportant.

Again, not an engineer and just parroting what I've heard over the years.
 
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