What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Do you hand turn prop to move oil?

RickWoodall

RickWoodall

Well Known Member
Just a question. If your plane has sat for two months (paint shop), or even a week or two when you pull it out, if temps outside arent too low, do you turn the prop to splash oil around?
I see a lot of older pilots do this, claim in gets a little oil moving and does no harm. Seems like a good idea. Of course safety first, key out, master off, stay clear of prop if it catches but... is this good practice?

Picking my plane up tomorrow, hasnt been started for over two months. Nice new engine, temps will be warm etc, just thinking of the best prep.

Open to arguments for and against.
 
Absolutely NOT!

Lycoming says either start the engine or leave it alone.

Turning the prop simply wipes the oil off the cylinders and leaves them dry. Same with the camshaft. The cam lobes are oiled only by splash when the engine is running.
 
What Mel said, leave it alone.

Its a different case for a R-985 or any other radial engine, where one could get hydraulic lock and thats where the idea came from.
 
The only time I've hand-turned a prop to "move oil" was when the plane had been sitting for long enough to lose its oil pump prime. I removed a plug on each cylinder and spun the prop as fast as I could (no starter) to re-prime the oil pump so that I'd have oil pressure on startup. Of course, this is unrelated to your question, and the advice already given by others is correct.
 
Did it on my 0-360 in my 1969 177A Cardinal since 1985. I averaged 50 hrs a yr and most of that in the summer. So there was a lot of time that the plane did not fly. I would turn it over a dozen times by hand every couple of weeks. Compression was always 76 to 78/80 and never any problems. The engine was last rebuilt in 1975 and still running with no top overhaul.

You turn it over enough it will pump oil through the motor enough to lube most of it and of course to wipe off any corrosion before it starts.

When the motor was cold I would 1st turn it over a couple of times to loosen up the oil, give it a couple shots of primer and turn it over 2 or 3 blades by hand, climb inside and hit the starter and it would always fire on the first stroke and be up and running. This would reduce the long draw on the battery as it was in the back of the plane and the stress on the starter.

For me it worked this way. Can?t argue on success.

And it can get cold here in Canada.
 
hand proping for oil circulation

Hand proping for oil circulation is good for radial engines.

Not good for Lycoming 320/360 engines.

Reason: The cam is not lubricated when hand proping.

Many planes have had the engine case split to replace the cam only. Sad.

Follow Lycoming's advise. Don't hand prop.

Start engine and run it to operating temp.

I use Cam Guard additive when known sit time will be happening.
 
Mel said:
Lycoming says either start the engine or leave it alone.

Turning the prop simply wipes the oil off the cylinders and leaves them dry. Same with the camshaft. The cam lobes are oiled only by splash when the engine is running.
Click to expand...

What does the starter do??;)
 
Mel said:
The starter does NOT turn the engine fast enough to sufficiently "splash" oil onto the cam.
Click to expand...

I was just poking fun at you Mel, cranking the engine to start it removes the oil too and it's a few seconds before anything gets splashed.:) I am on your side, I don't turn the engine by hand either. It's a waste of time just for the reason's cited here.
 
Last edited:
Don Jones said:
I was just poking fun at you Mel, cranking the engine to start it removes the oil too and it's a few seconds before anything gets splashed.:)
Click to expand...

Yeah, but you're not worried about stagnating corrosion if you're using the starter, 'cause that means you're going flying. ;)
 
Those motors that had the cam problems, were they all motors that were turned over like I do? Or were they motors that sat and people did nothing with them and would let the rust and corrosion start and then the damage would begin once they started their engines up months or years later?

Or maybe the lifters had not been replaced when they changed the cam or even installed the wrong lifter on a different lobe after a rebuild? or or or?

From what I have seen on the Lycoming the oil will be pumped to the rockers, run down the push rod to the lifters to pump up the hydraulic lifters and some of this will spill over onto the cam lobes enough to coat it again. Yes the splash from the crank will also add to the lubrication.

If you only turn it over a blade or 2 then you won?t pump enough if any oil through the system and you could be doing more harm than good. How many turns by hand does it take to move the oil is a good question but from what I was doing I believe it had worked for me.

In setting my lifters in my V10 Viper by the time I would get everything apart some of my lifters would have bled down (yes I know there was an issue with these) making setting my lash more difficult. So I would crank it over a few times and I would have oil on the floor and my lifters would be pumped up and I could continue setting my lash.

Does anyone know for sure that the oil that pumps up the lifter does not ever reach the cam lobe on the Lycoming?
 
I'll go further than Mel; either bring the oil up to operating temperature (180F) so you can drive out the water, or don't bother to start it.

Erich
 
I'll go even further.....

erich weaver said:
I'll go further than Mel; either bring the oil up to operating temperature (180F) so you can drive out the water, or don't bother to start it.
Erich
Click to expand...

and say that this shouldn't be done on the ground. The cooling system on our aircraft are not designed to cool properly on the ground.
If you run on the ground long enough to get the oil to operating temp, the cooling will not be properly balanced.

Flame suit adorned!
 
Mel said:
and say that this shouldn't be done on the ground. The cooling system on our aircraft are not designed to cool properly on the ground.
If you run on the ground long enough to get the oil to operating temp, the cooling will not be properly balanced.
Click to expand...

Sounds like an excuse to fly more.
 
Maybe - maybe not

The lycoming dicta is clear. Don't do anything unless you can fly the aircraft for at least a half hour with the oil temp indication at 180.

Still...during my build (I really don't recall why - probably testing the spinner for wobble) I had the occasion to spin the prop with plugs removed. I probably turned it a half dozen times and was shocked to discover an oil puddle about 15 feet off to the side of the airplane (almost out to the wing tip). Where did the oil come from? A pin hole in the filter and it shot that far just based on the pressure from hand turning the prop. At the Lycoming piston engine school they tell you (and I've forgotten) the pressure that little pump is capable of and I recall being really surprised how much oil just dumps back into the case from the relief valve.

So, my anecdotal question is - do you want to take care of the cam and lifter bodies or the cylinder walls? (I currently have my Cherokee engine apart to replace the cam & lifters. It appears to me that there are several oil outlets on each side of the case intended to put oil on the cam. I think if you turned the engine by hand energetically, you could do that.)

If I had nickel carbide cylinders that can't rust, I wouldn't think twice about turning it by hand. If I had the steel nitrides and wasn't going to fly a lot, I'd turn it once in awhile for the benefit of the cam & lifters and follow the Lycoming service instructions for preservation for the benefit of the cylinders.

YMMV

Dan
 
Turn by hand

I was taught in flight school to turn the engine over by hand a couple of times to help redistribute oil that may have settled in the cylinders, but we were always going flying after that, so is that also not a good idea?

Also, and I never understood why, several instructors said to turn the engine backwards when I did this. Anyone have a reason for this???

Finally - I like turning the engine by hand before starting so that I can feel the strength of the compression strokes in all 4 cylinders.
 
Av8torTom said:
Also, and I never understood why, several instructors said to turn the engine backwards when I did this. Anyone have a reason for this???
Click to expand...

A magneto will not fire the engine when turned backward.

On the other hand, it's been determined that a vacuum pump will likely be damaged when turned backward.
 
The oil pump normally is a gear pump and it will pump a small amount of oil even at lower rpm. Like what Dan has seen as well as I and supports my practice and the lubrication of the cam and lifters.

There are a lot of theory?s on why the problems with the cam and lifters and no real definitive answers. QC and QA come?s up quite a bit and has always been an ongoing problem of one sort or another.

That is why we have Recall?s in the Auto Industry. Or in the case of Aircraft we are issued AD?s and SB and who picks up the tabs on these?

We all remember when we were told we could not burn auto fuel in our planes and the reasons why? Well what are we doing now?

Another good point that I missed is if you have a cylinder going south you could very well catch it while you?re still on the ground.

Tim
 
riobison said:
From what I have seen on the Lycoming the oil will be pumped to the rockers, run down the push rod to the lifters to pump up the hydraulic lifters and some of this will spill over onto the cam lobes enough to coat it again.
Click to expand...

No...oil is pumped via galleries to the lifter, then moves via the pushrod bore to the rockers.

Does anyone know for sure that the oil that pumps up the lifter does not ever reach the cam lobe on the Lycoming?
Click to expand...

Leakage between the lifter body and the case bore can't directly reach the cam lobe....it's on the other side of the mushroom.
 
If you had to revive a long dormant Lycoming, would it be worthwhile to put new oil in, and use a sump pre-heater to warm the oil before the first start?
 
BD4 guy- I recently revived a long dormant Lycoming. I pulled top spark plugs and borescoped them to look for corrosion, then put a few ounces of marvel mystery oil in each with mags/master off and battery removed. Pulled prop through by hand about 50 times, let it sit overnight and did it some more.

On second day I changed oil and replaced battery. It started on about the fourth try after a few shots of primer. Compressions were about 65 on all four cylinders.

You will probably want to change the oil again very quickly and cut open filter to look for metal,etc. After my second oil change and it having been run a few times, the compression up to 73 on all four cylinders, should creep up a bit more with use hopefully.
 
I'm backing up Dan Horton

The way I see it and I built up my IO-360 from Superior Air Parts is that the "cam lobes" and lifters(followers) that actually contact the cam lobes get their primary lubrication from oil splash during engine operation. Oil slinging around inside crankcase during running if you will. Just turning prop by hand is not going to do this. Plus it's thicker oil. The cam shaft itself is lubricated by I think 4 bearing journals that get their lube from oil gallery's in the case, but that's not gonna get over to the cam lobes and lifters the way you want it too. So, even like Mel said. Don't bother turning over unless your gonna fly it. Some day I might try this Cam Guard stuff myself, but I do run my engine at least a couple times a month in Central Florida. Good Luck and my flame suit is on if somebody begs to differ. :rolleyes:

Jeff Liebman
RV-8. 370TT
Airglades Airport, FL

P.S. My first post ever and I've been lurking here since the beginning I think. What took me so long?
 
As has been pointed out, the primary cam lobe lubrication method is from oil flung off the big end of the rods. Some engines have a little notch which directs oil out of the rod journal, but it is common wisdom that there is enough leakage due to endplay that this "squirter notch" is not required.

Any time you turn an engine slowly, you not only DON'T have a supply of oil to the most critical wear area of the camshaft (lobe/lifter interface), it is also slow enough that you don't get the benefit of the hydrodynamic wedge which keeps the metal from making actual contact. At rest you have the valve spring pressure forcing the lobe and lifter into hard contact; turning the assembly just wipes the residual oil right off.

It has been said that those few seconds grinding away on the starter do more damage than several hundred hours of running time. Conversely, if you used a Lycoming continuously (like to run a generator or water pump), it would run tens of thousands of hours before needing overhaul. Starting is very hard on an engine
 
Toobuilder said:
It has been said that those few seconds grinding away on the starter do more damage than several hundred hours of running time. Conversely, if you used a Lycoming continuously (like to run a generator or water pump), it would run tens of thousands of hours before needing overhaul. Starting is very hard on an engine
Click to expand...

Amen! The worst thing you can do to an engine wear-wise is to start it. The second worst thing is to shut it down...

Anytime my engine has not been run for more than a couple of months, I pre-oil it with a pressure pot.
 
Well it appears that I?m the only one doing this and I have been doing it for over 32 yrs on all of the planes that I have had and I have never touch any of the cam?s nor the lifters.

The last one being the Cardinal with 37 yrs and just over a 1000 hrs on the engine. Neither the cam nor the lifters have been touched.

Maybe I have been lucky or maybe it is my technique but it has worked for me so I will continue my practice.
 
I live in a dry climate but use Camguard and an engine dryer system. I have no way to document that this is better than doing nothing, but the cost is trivial and logically is a good thing to do.

I also use an oil sump heater for temps below about 50 deg F.
 
Last edited:
riobison said:
Well it appears that I?m the only one doing this and I have been doing it for over 32 yrs on all of the planes that I have had and I have never touch any of the cam?s nor the lifters.

The last one being the Cardinal with 37 yrs and just over a 1000 hrs on the engine. Neither the cam nor the lifters have been touched.

Maybe I have been lucky or maybe it is my technique but it has worked for me so I will continue my practice.
Click to expand...



I find your technique interesting can you also tell me have these aircraft been in heated or non heated hangars ?
 
Fly The Engine

One of the books in Van's bookstore and also recommended by one of my mentors is "Fly The Engine" by Kas Thomas.

Page 24 starts with "My own personal policy is to rotate the propeller by hand prior to the first flight of the day, or any time the engine is cold." Later on the same page he states "Prop-turning is a somewhat controversial practice, at least as applied to modern flat-opposed engines."

As I don't have much experience with piston aircraft, I'm still in the information gathering phase and I appreciate threads like this. Better learn fast as my Aerosport 0-360 is due soon.
 
riobison said:
...Maybe I have been lucky or maybe it is my technique but it has worked for me so I will continue my practice...
Click to expand...

The fact that you have not caused any catastrophic damage by using this technique should not be construed as evidence that it is "working" for you.

The plain bearings used in the rods, crank and cam journals as well as the contact points and bushings in the accessory case geartain will live just fine on residual oil (zero oil pressure) while turning the engine by hand. There is simply no stress on any of these friction surfaces until the engine is pulling a load or generating heat with RPM. The same cannot be said of the camshaft lobe/lifter interface. The pressure "seen" at this point is the same at all times and all RPM because it is provided by the valve springs. However, the camshaft needs a good supply of oil AND some surface speed to allow the lifter to ride up on a wedge of oil. Much like a tire of a car will hydroplane during heavy rain and high speed - it will also settle back into contact with the road if you slow down or the rain lightens up.

Yes, instant oil pressure on start is a good thing, but the reason has little to do with the pressure lubricated parts. It is the parts that get the byproduct - the "splash" lubed parts that are really hurting the most.

...And turning an engine by hand does not help those at all.
 
Obviously I must be in the minority on here based on the replies but it seems as Larry says one of Vans books "Fly The Engine" by Kas Thomas.? also is a supporter.

As well my wallet says it?s working for me and has worked for the last 32 yrs.

I know for a fact that a car engine will pump oil through the engine when you turn it over by hand. I have cleaned up enough oil off the floor to know this when setting my lifters.

I will make it a point the next time my tappet covers are off I will turn the engine over the same as I do during my off season and see how much oil I?m moving. I can?t see why there would be much of a difference between an auto engine or a Lycoming as I believe the oil pumps are similar.
 
Toobuilder said:
The same cannot be said of the camshaft lobe/lifter interface. The pressure "seen" at this point is the same at all times and all RPM because it is provided by the valve springs.
Click to expand...

The tappet load is the sum of spring pressure and the the acceleration necessary to move the valve train from rest. The later rises significantly with increasing RPM.

riobison said:
I know for a fact that a car engine will pump oil through the engine when you turn it over by hand.
Click to expand...

As does your Lycoming.....but there is no pumped supply to the cam-tappet interface.
 
DanH said:
The tappet load is the sum of spring pressure and the the acceleration necessary to move the valve train from rest. The later rises significantly with increasing RPM...
Click to expand...

Yes, you caught me on an oversimplification. But to correct you, the load also decreases when the lifter goes over the nose of the cam at higher RPM due to valvetrain inertia.

That said, I think we're both in agreement that turning an engine slowly is not good for the cam/lifters on any flat tappet engine.
 
Last edited:
riobison said:
...I know for a fact that a car engine will pump oil through the engine when you turn it over by hand. I have cleaned up enough oil off the floor to know this when setting my lifters....
Click to expand...

...As have I. But pumping oil through the oil passages does not indicate ALL parts of the engine are lubricated. There is more to the story than simply seeing oil squirting out of the pushrods.

Getting oil pressure soon is a good thing, but if it's at the expense of another component, not so much.

I'm sure you have pre oiled a new automotive engine by pulling the distributor out and driving the oil pump with a drill motor just like I have, but you also remember that you want the engine to fire immediately and then run it at least 2500 RPM for the first 30 minutes or so for "cam break in". This "high" RPM ensures the cam is getting ample oil cast off from the rods.
 
Ney nozzle

If one were to inject oil under pressure via on of the galley access ports on the engine, would this not get oil onto the cam. The TMX engines come with "ney nozzles" I think that is what they are called. I think under pressure this sprays oil on the cam shaft area. I did not build the engine but watched one being built.

I could have this all wrong, but one guy at the build I watched said when he can't fly his plane he just pumps oil in this way and said it is his corrosion protection.

Any expert to confirm this. I would think the oil would have to be warm. I did this on my engine in storage periodically, in a few months we will see how it worked!!
 
Phlyan Pan said:
longranger said:
Anytime my engine has not been run for more than a couple of months, I pre-oil it with a pressure pot.
Click to expand...
I'm not familiar with this procedure. Can you describe it for those of us who haven't done this before?
Click to expand...

Below is a link to a picture of my home-brewed pressure pot pre-oiler. It leaks a little and makes a bit of a mess, but it gets oil where it needs to go. The can is an "Air Atomizing Sprayer", Mcmaster-Carr#7054T11 with the nozzle removed. The tubing, plastic tube-to-pipe adapter, and clamps are from my local hardware store.

With shop air pressure I've gotten 25-30 psi oil pressure at the end of the oil gallery. It may or may not get oil EVERYWHERE it needs to go, but it IS way better than pulling the engine through by hand.

file.php
 
Are you adding oil to the system with this preoiler? If so then eventually your going have to take out the excess oil.

Taking the cowl off to do the pre oiling looks like a lot of work. Maybe having something like this with quick coupler that you can reach from outside the cowl or through the inspection hole might be a good idea.
 
riobison said:
Are you adding oil to the system with this preoiler? If so then eventually your going have to take out the excess oil.

Taking the cowl off to do the pre oiling looks like a lot of work. Maybe having something like this with quick coupler that you can reach from outside the cowl or through the inspection hole might be a good idea.
Click to expand...

I don't pre-oil on a regular basis; only when I 'm about to start the engine after a long layup (more than a couple of months), either to fly, or prep for annual inspection. The photo I linked to was actually within a day or so of first start after overhaul, but I have done it once since then just before flying after a 9-month layup.
 
DanH said:
The tappet load is the sum of spring pressure and the the acceleration necessary to move the valve train from rest. The later rises significantly with increasing RPM.



As does your Lycoming.....but there is no pumped supply to the cam-tappet interface.
Click to expand...

The highest loading on a cam and lifter is at 1 RPM and it goes down with increasing RPM. The highest stresses on a Lycoming cam are in the middle of the ramp and not the nose. I measured all of this when I designed replacement cams for Superior Air Parts.

Ed

Edward Kollin
Technical Director
Aircraft Specialties Lubricants
 
RVG8tor said:
If one were to inject oil under pressure via on of the galley access ports on the engine, would this not get oil onto the cam. The TMX engines come with "ney nozzles" I think that is what they are called. I think under pressure this sprays oil on the cam shaft area. I did not build the engine but watched one being built.

I could have this all wrong, but one guy at the build I watched said when he can't fly his plane he just pumps oil in this way and said it is his corrosion protection.

Any expert to confirm this. I would think the oil would have to be warm. I did this on my engine in storage periodically, in a few months we will see how it worked!!
Click to expand...

Ney Nozzles do not spray until the oil warms to maybe 70-80degrees.

The camshaft will turn 500 -1000 revolutions until the oil flows out of the holes in the Centrilube camshaft. Neither will do anything for a true dry start.

Ed

Edward Kollin
Technical Director
Aircraft Specialties Lubricants
 
Wow, great first posts, Edward. Welcome! There's always so many opinions floating around, some more informed than others. I hope you stick around and teach us more about what you've learned along the way.

Best wishes,

Stephen
 
n761tj said:
The highest loading on a cam and lifter is at 1 RPM and it goes down with increasing RPM. The highest stresses on a Lycoming cam are in the middle of the ramp and not the nose. I measured all of this when I designed replacement cams for Superior Air Parts.

Ed

Edward Kollin
Technical Director
Aircraft Specialties Lubricants
Click to expand...

I'm quite curious how these measurments were made. Where were the force transducers? Strain gages on the push rods? Is this data proprietary?

Jerre
 
AeroDog said:
I'm quite curious how these measurments were made. Where were the force transducers? Strain gages on the push rods? Is this data proprietary?

Jerre
Click to expand...

Strain gauges mounted in a lifter substitute. The measurements were to confirm (directionally) the computer aided design.
The data is proprietary but I will see what I can dig up.

Ed

Edward Kollin
Technical Director
Aircraft Specialties Lubricants
 
Last edited:
You must log in or register to reply here.
Back
Top