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Bill Greenwood
07-30-2012, 04:36 PM
I went to two maintenance forums by Mike Busch, and it seems worthwhile.

But I have some questions in one area; that of the forum on oil types.
Mike says the main item of wear in an aviation piston engine is from corrosion, as when the engine is not being flown and is sitting.
He than picks his favorite oil type on this basis.
Now the conditions where a plane is based are a factor, for instance in the humid salty climate of the Gulf coast it may be a big factor.

But Mike really did not mention friction wear, especially on first start up on an engine which has not run in awhile and which is devoid of oil in the upper end.
I think this is the source of much wear, not just corrosion, especially where I live in Colorado that is very dry and part of the year is cold.
He likes single weight oil, like Aeroshell w100, and didn't advocate preheating the oil, before start up. I think in many parts of the country that will lead to wear on initial running.

I use a multigrade and usually preheat, or try to. Even in May or Sept we may have night temps down around 40 degrees and 100 weight oil doesn't pump very well through small engine passages then.

He also advocates changing oil every 4 months on a time basis, not just hours run. I don't know anyone who does that, don't know if it is good or overkill.

He likes oil analysis and checking the filter. It has been my experience that if the filter is clean, the analysis is likely to be also.

This is all sort of informed guess work or personal experience. No one takes 100 of the same engines and runs half of them on multigrade and the other half on w100, in the same conditions, to see the actual results, like you'd need to to the really have factual reports.

turtle
07-30-2012, 05:28 PM
But Mike really did not mention friction wear, especially on first start up on an engine which has not run in awhile and which is devoid of oil in the upper end.
I think this is the source of much wear, not just corrosion, especially where I live in Colorado that is very dry and part of the year is cold.
To prevent corrosion you want an oil that won't run off and leave the upper end dry. So solving one problem solves another. I agree with the need to preheat. I use W80 in the winter so preheating is not really optional. Even using multigrade, preheating is much easier on the engine. What you don't want to do is run a heater then not fly the plane.

Bill Greenwood
07-30-2012, 06:07 PM
I am not very convinced about this idea of "an oil that won't run off" and leave the upper end dry.

Now,there are some tests or rather demonstrations that try to show that thick oil won't run off of a part like a thin oil will. But it is not very convincing. First ,when an engine shuts down after a flight, the internal parts are several hundred degrees. Any oil, be it 15-50 , or w100 is going to be thin at that temp and "run off". It's not cosmoline grease! And all parts are not vertical anyway.

What is needed is an oil that is thin enough when cold to flow on start up and provide good lubrication right away. And id the weather is cold or even cool enough to prevent that thick oil from flowing, then the small amount that is left on a part after shut down is unlikely to provide enough lubrication to prevent wear on starting up.

WLIU
07-31-2012, 04:37 AM
Lyco engines splash lube their cams unlike auto engines. The cam is above the crankshaft. If the oil is thin enough to run off while the airplane sits, the cam gets a lot of wear on start up until enough oil is thrown up onto it. Cam bearing loads are not a function of RPM but more a function of the valve springs so starting slow does not reduce cam wear. See the issues with the O-320 -H engines in the Skyhawks.

It takes even longer for oil to get to the top end of the cylinders. Take your rocker covers off some time, wipe down the residual oil, start the engine and watch. You will be surprised.

Multigrade is great if you fly a lot. Not so much if you fly a couple of hours a month. Mike B is no dummy.

Best of luck,

Wes
N78PS

Bill Greenwood
07-31-2012, 02:42 PM
Wes, you may have misunderstood what I thought I wrote. Nothing I wrote was that Mike is a dummy.
But I question some of his ideas from the forum on Fri.
1. That corrosion is the number one wear item.
He barely mentions friction wear, including start up wear from not having oil pumped through the engine instantly.
2. That thicker base stock oil is better, because it does not "run off" as easily after engine shut down and thus protects against corrosion.

And as for as seeing oil being pumped with the rocker covers off, while I have not seen it myself, I am told that in some cases like a Merlin it can take a minute to get oil up to the upper end cams and followers.

I think anything one can do to shorten this waiting time for upper end lube is good, and the two main things are most likely to be using multigrade oil which will flow on start up even if fairly cold, and to preheat if possible anytime it is cold .
There are people who claim they don't need to preheat because they live in the south, but I have seen it below freezing in both Texas and Florida.

I don't think the answer to wear, is to use thick stock oil which will not flow well when cold and hope that enough of the thick oil will stay on the parts when shut down to protect the parts on the dry start up.

I don't use a Lycoming now, but when I did have a IO-360 in my Mooney M20J it went to 2000 TBO using multigrade oil, Aeroshell 15-50.
I don't really see this question of what makes most of the wear as dependent on whether one has a Lycoming or Continental or other make.

Joe Delene
07-31-2012, 03:25 PM
I was able to fit in one of his seminars dealing mostly with leaning. I enjoyed it, learned a few things too. I also read his stuff in Sport Aviation 1st thing. It is impossible for us to treat 2 engines the same & with different oil, them compare results. Most are lucky to have one engine.

In my 0320, S WI I use 100w + Shell in the summer & 15w-50 from mid fall to mid spring. I also preheat with night temps below 45 or so. I only preheat 24 hours or less before a flight if needed, not plugged in all the time in the winter. I also try to never go over 14 days or so without a flight. I've not yet felt the need to do the Camguard thing. I have given it some thought & I do think it could be an added benefit, it's the AMOUNT of benefit I debate. My main focus is an oil change around the 4-5 month window, the hours may be 25-35, depending.

If I anticipate the plane won't get flown a lot, I like clean oil in it. I would still take it up every 2 weeks or so for 30 minutes minimum.

My usual rotation is 3 oil changes a year, 2 myself & one with the annual. I bought a 6 pack of Tempest filters at Airventure so I'm good for a while. I just don't like dirty oil sitting in the engine. Maybe I could back that off to 2 changes, not quite there yet though. I do think Camguard is more helful if you plan to sit a while without flying.

Bill Greenwood
07-31-2012, 05:08 PM
Joe, you are the only guy I know who changes oil every 4 months regardless of hours run, especially on an O-320.
Mike does not like 15w-50, prefers Phillips 20w-50. He says Camguard is good only drawback is price, $25 pint?. He mentioned 2 additives by name that may be harmful, think Microlon and ?, and others that seemed useless.
If Camguard saves one teardown or one replaced part it is worth the price.

Until there is are real world scientific tests, not just putting some pieces of metal in a rust cabinet, we don't really have facts on engine wear and it is all just opinion; even if in some cases it is informed opinion.
One way to test oils would be if some flight school had piston twins and put single wt oil in one engine and multi in the other for instance, both operating under the same condition.
There was one vendor at EAA selling some product and their total proving evidence was to run it in only two single engine planes.
Rolls Royce used to run engines on test stands 24 hours a day, not to test oil, but other factors. They did not have to guess or hypothosize, they knew what was happening in an engine.No one in avitation, at least that I know, does this. Mostly human nature makes or finds a theory and accepts anything that supports their theory and bypasses anything that conflicts with it.
This narrow focus is not limited to a few, and being bright and educated is no cure all. For years almost all doctors accepted the belief that stomach ulcers were caused by conditions, like eating greasy food. It seems they belived just because everyone else believed. Then one young doctor in Australia did his own research and found a virus or bacteria, (might be called pliorethra, I can't remember for sure) that really was the cause of at least one kind of ulcer. He was belittled by the "experts" the other doctors for a year or two, until finally some did the research on their own and confirmed the fact.

Mike sees a lot of maintenance and his would certainly be an informed opinion.

Mike Switzer
07-31-2012, 05:40 PM
Back in the 90s Smokey Yunick wrote an article for Circle Track magazine about oil, the one thing I remember is he liked thick high parrafin oils, especially for race engines that may only get started up once a week & sit all winter as the oil "sticks to everything" and prevents corrosion & helps provide some lubrication on startup. You especially want enough oil on the crank bearings to keep them from scuffing until you get enough oil pressure to prevent contact between the crankshaft & the bearings.

Mike Berg
07-31-2012, 06:16 PM
I've read several of Mike's articles and he makes some good points. However, I always preheat if the temperature is much below 40 degrees. I've used Phillips 20-50 XC for 30+ years in all the aircraft I've owned with no unusual problems and the aircraft usually sit from late November until March. Also, after an engine has run for a few years most of the running parts get a light coating on them which I feel tends to prevent rust or at least slow it down. My new 0200 ECI cylinders (nickel) recommended 20-50 XC for break in and the life of the engine for whatever that's worth.

nrpetersen
07-31-2012, 07:09 PM
I too followed the preheat below 40 degF on a trouble free O-320 that ended up at 1700 TTSN but also 35 years SN when I sold it. It is still running strong 5 years later based on the present owner's reports. The oil & filter was changed evry ~35 hrs or annual whichever came first.

Lycoming engines have the cam in the top of the crankcase as many of you know. If you line up the crank and the cam against each other as they are in service, you will see that there is no feature on the crank to splash bearing leakage oil on the cam lobes. This means the cam lobes require the general fog of oil for lubing that only happens with a warmed up engine. If you look at the leakage from a journal bearing vs viscosity vs start up temperature etc it is obvious that the amount of oil flying around inside a crankcase during a cold start is pretty tiny - and the oil blowing over the oil pressure relief valve has no access to the heat of the engine.

I'm convinced that's why warm up is so slow, and why cams are so troublesome in Lycoming engines - especially when new & with closer clearances.

What's really needed is for someone to cut a hole in the wall of a scrap crankcase & run a cold spinning test to see how long it takes to get the oil fog.

WLIU
07-31-2012, 07:49 PM
There are two solid solutions to the Lyco camshaft issue. One is the Ney nozzles that put a spray on the cam lobes. No delay in lubrication at startup. Another vendor drills the cam to be like an automotive cam where there is again pressure lube.

The bad news is that you can only install these mods at engin e overhaul time. I did the Ney nozzles.

I run Aeroshell 100W+ all year round in New Hampshire, but I have a hangar and can preheat every winter start when the temps are below 35F.

Best of luck,

Wes
N78PS

Tom Downey
07-31-2012, 11:17 PM
What's really needed is for someone to cut a hole in the wall of a scrap crankcase & run a cold spinning test to see how long it takes to get the oil fog.

THat is exactly what Chuck Ney did when he invented the Ney Nozzle which cured the 0-320-H2AD engine problems.

Joe Delene
08-01-2012, 02:56 AM
I also have the 'Ney' nozzles in my 0-320. Hope they help in there. They came already installed when the previous owner did the 160 HP conversion/overhaul.

Bill Greenwood
08-01-2012, 10:44 AM
Small Lycomings may have certain problems. I think there is or was an oil additive for this, 1506?
My IO-360 went to TBO, no problems other than using a good bit of oil at the end.

Mike's forum was not focused on any one brand engine, in fact his twin Cessna has a version of the same engine my Bonanza does, Continental TSIO 520

WLIU
08-01-2012, 11:51 AM
A number of oils now come with the Lyco camshaft additive blended in. AeroShell 100+ is one (the "+" denotes the difference from regular 100). The 15w50's also contain the Lyco additive. The Lyco additive probably helps Continentals also, although their camshafts are better lubed in their location under the crank.

Best of luck,

Wes
N78PS

Eric Page
08-02-2012, 09:09 PM
It's curious to me that no one has developed a system to pressurize the oil galleries pre-startup. Doesn't seem like it would be much of a technical challenge to develop an auxiliary electric oil pump that could circulate oil through the engine before starting, eliminating the metal-on-metal startup wear. If the pump had an auxiliary power connection on it, it could be plugged into a timer that ran the pump to pressurize the oil galleries for, say, five minutes a day, keeping engine internals well-coated between flights.

Somebody tell me why I'm nuts here.

Mike Switzer
08-02-2012, 09:21 PM
Some race cars do have electric pre-oiler pumps. I don't recall exactly why, unless it was because the tolerances were very tight, as the ones I know of were all on engines that ran one race & were replaced.

martymayes
08-02-2012, 09:31 PM
It's curious to me that no one has developed a system to pressurize the oil galleries pre-startup. starting, eliminating the metal-on-metal startup wear.

They have. Google "Oilamatic Inc" for details on one option. I've seen a few in the field but for the most part it's not a very popular add on.

Bill Greenwood
08-03-2012, 07:47 AM
Eric, I have a pre oil system, (not Oilamatic) on one of my engines, after preheating for a few hours to overnight, I run the pump about 2 min before starting. The preheat is via electric pads that are glued onto the outside of the oil pan, thus it heats the oil, and as you run the pump you can see the oil temp register on the gage on the panel. I use Philllips 25w-60 for that plane. If I had just straight weight thick oil, like w120 or w100, it would not flow that well if cold. I live at 8000 feet in Colo and even this summer morning, Aug 3 the temp is 45 degrees at 7 am, so an early morning start up is pretty cold. Human skin doesn't like this ultra dry climate too well. I once lived in San Diego where the humidity averages about 50 to 60 per cent, great for your skin. Can't say much for the air pollution there, and the air is salty near the coast.

My Bonanza has a Tanis preheater, so it heats the cylinders when I plug it in the night before. It certainly is not as good as starting in warm weather or being in a warm hangar.

It is very dry in Colo, sometimes way too dry, like 10% humidity, so I don't see corrosion as much of a problem in an engine, but that is just opinion, like most people.

1TJ
08-12-2012, 09:11 PM
There are two solid solutions to the Lyco camshaft issue. One is the Ney nozzles that put a spray on the cam lobes. No delay in lubrication at startup. Another vendor drills the cam to be like an automotive cam where there is again pressure lube.

The bad news is that you can only install these mods at engin e overhaul time. I did the Ney nozzles.

I run Aeroshell 100W+ all year round in New Hampshire, but I have a hangar and can preheat every winter start when the temps are below 35F.

Best of luck,

Wes
N78PS

Ney Nozzles only spray pressurized oil when it is above 70-80 degrees.
And the cam will turn 250-1000 revolutions before oil flows from Centrilube cams holes.
Neither addresses a true dry start.

Ed

Edward Kollin
Technical Director
Aircraft Specialties Lubricants

WLIU
08-13-2012, 06:37 AM
That is why I have a timer turn on the preheater 3 hours before I go fly on cold days, and I use oil that contains the Lyco camshaft additive.

The roller cams in Lycos also address the issue. But you have to have a recently overhauled engine to get those.

The best option is to fly a lot so that the cam has residual oil on it at the next start.

Camshafts live a hard life, but most seem to make it to their first TBO with only a little consideration on the part of the operator. But of course some pilots don't make the briefing....

Best of luck,

Wes
N78PS

1TJ
08-13-2012, 11:30 AM
Here is a picture of a Lycoming roller cam with 300 hours and 1 1/2 years old. Engine tear down because of a prop strike when they discovered this. The Lycoming engineers were NOT happy when they saw this! Corrosion kills more engines, by far, than anything else. And the Lycoming additive, LW-16702, does nothing for corrosion.

2363


Ed

Edward Kollin
Technical Director
Aircraft Specialties Lubricants

nrpetersen
08-14-2012, 10:14 AM
That must have had some awful oil in it. Note there is even corrosion in the camshaft bearing journal

Bill Greenwood
08-14-2012, 10:37 AM
i'd like to know more details about this engine, and see some photos of the rest of the parts. If the damage was caused by corrosion, then there would likely be similar damage on other parts.I noitce there is no damage in the photo on the side of the cam or on the tan colored part. Why is it only on the polished part, and not on the nose or top of the cam lobe?

I have seen upper end wear on cam followers and cam faces in Merlins. I have never seen any evidence of corrosion in one, just friction wear, which seems to be mostly from inadequate lube on first start up. And note most Merlins are not flown much during the winter.

Maybe Lycomings are different and very subject to corrosion.

WLIU
08-14-2012, 11:25 AM
Is that corrosion? Looks more like a failure due to manufacturing. Heat treating done wrong? I agree that there has to be more to the story and that is likely why the Lyco folks are concerned.

Best of luck,

Wes
N78PS

1TJ
08-14-2012, 01:14 PM
Aeroshell W100 changed every 50 hours.

Ed

Edward Kollin
Technical Director
Aircraft Specialties Lubrcants

1TJ
08-14-2012, 01:28 PM
i'd like to know more details about this engine, and see some photos of the rest of the parts. If the damage was caused by corrosion, then there would likely be similar damage on other parts.I notice there is no damage in the photo on the side of the cam or on the tan colored part. Why is it only on the polished part, and not on the nose or top of the cam lobe?

I have seen upper end wear on cam followers and cam faces in Merlins. I have never seen any evidence of corrosion in one, just friction wear, which seems to be mostly from inadequate lube on first start up. And note most Merlins are not flown much during the winter.

Maybe Lycomings are different and very subject to corrosion.

The plane was flown a lot (300hours/1.5 years) but sat for a few weeks at a time. The damage is due to spalling initiated by corrosion. There were rust spots on crank and gears. No rust on the copper covered or unpolished parts of the cam. This type of pattern is quite common because the carburization process, used to harden the cam, makes it quite susceptible to pitting along grain boundaries, which in turn causes the stresses that lead to spalling failure. Chilled cast iron, used in lifters, is also susceptible to this problem.

Ed

Edward Kollin
Techical Director
Aircraft Specialties Lubricants

WLIU
08-15-2012, 04:29 AM
So a few years ago when I had the choice of what cam to buy for my overhaul, I chose a Superior cam which I understand is a "billet" cam rather than just a case hardened assembly. Does that type of cam resist the situation pictured more than the stock Lyco unit?

Thanks,

Wes

nrpetersen
08-15-2012, 08:18 AM
I'm still bothered by the corrosion on the camshaft bearing journals that should have been protected from corrosion on shutdown by oil retained in the bearings. Something is fishy here.

Bill Greenwood
08-15-2012, 11:10 AM
Maybe the Lycoming cams are made cheaply, that is of an inferior metal and/or an inferior hardening process. Obviously price is a big factor in engine cost at the trainer level.

I know I have never that seen that type of wear, if it is corrosion, in the cam area of a Merlin. Now obviously Rolls Royce and even Packard were trying to produce the best engines, not the cheapest, so maybe their quality is that much superior.

I have seen friction wear and/or lack of lubrication make rough spots on cams and followers. A follower is sort of like a rocker arm, Merlins don't use lifters as they have overhead cams.

I heard a story years ago that some American car cam makers tried to grind some new Merlin cams, but when they took a short cut in the heat treating and hardening process, the resulting cam wore out too fast.

Aaron Novak
08-23-2012, 08:59 AM
Couple questions I would ask on the cam above would be:

1-Where is this aircraft flown and stored? Climate plays a big role here.

2-What fuel was used? MoGas or AvGas?

Unfortunately in the picture above, someone has "polished" the lobe and journal to "pretty it up" , so much of the information is not present. Also to answer a question, the nose of the cam in not loaded as highly as the flank, and so where we see the pitting ( not convinced its spalling ), is in the highest loaded area. The journal corrosion, and the note of corrosion on the other steel components leads one to believe there was something in the operation of the engine that led to moisture/acids in the oil attacking the parts.

1TJ
08-24-2012, 08:43 AM
Couple questions I would ask on the cam above would be:

1-Where is this aircraft flown and stored? Climate plays a big role here.

South Africa - Flown mutiple times per week.



2-What fuel was used? MoGas or AvGas? Avgas





Unfortunately in the picture above, someone has "polished" the lobe and journal to "pretty it up" , so much of the information is not present. Also to answer a question, the nose of the cam in not loaded as highly as the flank, and so where we see the pitting ( not convinced its spalling ), is in the highest loaded area. The journal corrosion, and the note of corrosion on the other steel components leads one to believe there was something in the operation of the engine that led to moisture/acids in the oil attacking the parts.

There was no polishing done to this cam. It had rust that started the spalling process as we have observed over the past 20 years.

The only question I have is what is responsible for the rusting in the first place. My guess is that the engine sat unused at some point. Probably when it was waiting to be installed.

Ed

Edward Kollin
Tehcnical Director
Aircraft Specialties Lubricants

Aaron Novak
08-24-2012, 10:48 AM
Hi Ed,
Thanks for the answers. Any engine, aviation or not is subject to corrosion from storage. However having it to such an extensive degree on a surface thats sheilded by a bearing is fairly abnormal. Any chance that there is are oil samples as well? Fuel samples either?

f_lunn@yahoo.com
09-23-2012, 06:44 AM
Now you know two! I change oil ( and filter) every 3-4 months, regardless of flight time. I also fly my plane for 35-45 minutes at least every 3 weeks, if for some unfortunate reason I have not been able to fly it more often.