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  #31  
Old 03-31-2012, 10:08 PM
riobison riobison is offline
 
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Location: Oliver BC & Red Deer Alberta Canada
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Ed,

From 1980 to 1988 everything was outside. After 1988 I had a non heated hanger.

Tim
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  #32  
Old 04-01-2012, 09:03 AM
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Toobuilder Toobuilder is offline
 
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Originally Posted by riobison View Post
...Maybe I have been lucky or maybe it is my technique but it has worked for me so I will continue my practice...
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.
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  #33  
Old 04-01-2012, 07:58 PM
riobison riobison is offline
 
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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.
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  #34  
Old 04-01-2012, 08:20 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by Toobuilder View Post
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.
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.

Quote:
Originally Posted by riobison View Post
I know for a fact that a car engine will pump oil through the engine when you turn it over by hand.
As does your Lycoming.....but there is no pumped supply to the cam-tappet interface.
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  #35  
Old 04-01-2012, 10:55 PM
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Toobuilder Toobuilder is offline
 
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Originally Posted by DanH View Post
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...
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.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C

Last edited by Toobuilder : 04-01-2012 at 11:07 PM.
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  #36  
Old 04-01-2012, 11:05 PM
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Quote:
Originally Posted by riobison View Post
...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....
...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.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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  #37  
Old 04-02-2012, 06:54 AM
Phlyan Pan Phlyan Pan is offline
 
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Location: Rochester, NY
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Quote:
Originally Posted by longranger View Post
Anytime my engine has not been run for more than a couple of months, I pre-oil it with a pressure pot.
I'm not familiar with this procedure. Can you describe it for those of us who haven't done this before?
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  #38  
Old 04-02-2012, 10:53 AM
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RVG8tor RVG8tor is offline
 
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Location: McKinney, TX
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Default 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!!
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  #39  
Old 04-02-2012, 12:38 PM
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longranger longranger is offline
 
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Quote:
Originally Posted by Phlyan Pan View Post
Quote:
Originally Posted by longranger
Anytime my engine has not been run for more than a couple of months, I pre-oil it with a pressure pot.
I'm not familiar with this procedure. Can you describe it for those of us who haven't done this before?
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.

http://www.cessna170.org/forums/down...3972&mode=view
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  #40  
Old 04-02-2012, 03:20 PM
riobison riobison is offline
 
Join Date: Jul 2011
Location: Oliver BC & Red Deer Alberta Canada
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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.
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