Engine Maintenance / reliability (distilled from Busch's Engines)

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samiamPA

Pre-takeoff checklist
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samiamPA
I just read through Mike Busch's engines book. As a pilot and owner of a C-150 with a Continental O-200, I have a vested interest in keeping my engine running reliably. I was hoping that this book would help me glean some knowledge on how to decrease my chances of having an in flight engine failure.

Here's what I got out of the book:
1. Avoid corrosion. This can best be done by flying often and using Camguard. Change oil regularly and at least every 4 months, no matter how many hours.
2. Avoid unnecessary maintenance, especially pulling cylinders unless absolutely required.
3. Oil filters: cut open for inspection.
4. Oil sample analysis (editorial: still not convinced there is great evidence that this helps avoid engine failures)
5. Monitor CHT and avoid going above 400 for Lyc's and 380 for Conti's (doesn't help that my C-150 does not have a CHT monitor... at least they notoriously run cool)
6. Avoid cold starts without preheat
7. Run LOP (again, impossible for me - but the point being to avoid high CHT's)
8. Boroscope is king (don't rely on compressions)

Anything I'm missing? I guess I was hoping for more of a magic bullet to prevent engine failure, but I guess it's more looking for subtle abnormalities in the above recommendations - i.e., abnormal oil consumption, metal in the filter, or abnormal boroscope findings.
 
Lean aggressively on the ground and when appropriate in flight (2400rpm=65%, lean until rough, enrich until smooth). Run ethanol-free mogas if you can. Let it warm up when it's cold, until it quiets down and smooths out, usually <5 mins. I cover up the lower inlets in cooler weather to keep the oil temp up, which helps drive moisture out.
 
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GeorgeC said:
Lean aggressively on the ground and when appropriate in flight (2400rpm=65%, lean until rough, enrich until smooth). Run mogas if you can. Let it warm up when it's cold, until it quiets down and smooths out, usually <5 mins. I cover up the lower inlets in cooler weather to keep the oil temp up, which helps drive moisture out.
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Can you elaborate on the "run mogas if you can" point? I've got the mogas stc on our Lyco 320, but our A&P has pretty strongly advised me to stick with 100LL. Thanks...very interested in your point of view.. and so is my wallet...
 
No lead-induced valve problems.
 
The biggest thing you can do.... buy a $300 usb bore scope and learn what good valves and cylinders should look like. Every time you change your oil have a look inside each cylinder.
 
GeorgeC said:
No lead-induced valve problems.
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Not being argumentative... just sincerely interested in learning more. Is your information based upon the prerequisite of using ONLY ethanol-free mogas? Despite the potential for valve fouling and lead deposits on plugs if not leaned enough when required (esp low rpm ground ops), doesn't lead add to engine health in some way? Fuel stability issues?

Thanks...
 
Use Phillips 20-W-50, change at 25 hours, and no cam-guard. at 25 hours you won't need it.
Lean aggressively. (everyone can lean)
run a 2 to 3 mixture of 92 Ul and 100LL
install a filter.
 
25 hr oil changes is not why you want camguard.

It sticks to surfaces longer to prevent corrosion. It also saves seals.
 
MuseChaser said:
Can you elaborate on the "run mogas if you can" point? I've got the mogas stc on our Lyco 320, but our A&P has pretty strongly advised me to stick with 100LL. Thanks...very interested in your point of view.. and so is my wallet...
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This video is worth watching...

 
Checkout_my_Six said:
25 hr oil changes is not why you want camguard.

It sticks to surfaces longer to prevent corrosion. It also saves seals.
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Frequent flights are better, and cheaper.

wonder why we got away without it for so long?
 
MuseChaser said:
Not being argumentative... just sincerely interested in learning more. Is your information based upon the prerequisite of using ONLY ethanol-free mogas? Despite the potential for valve fouling and lead deposits on plugs if not leaned enough when required (esp low rpm ground ops), doesn't lead add to engine health in some way? Fuel stability issues?

Thanks...
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No problem, I edited my post to clarify. Yes, ethanol-free mogas, assuming a type certificated aircraft with a low compression Continental or Lycoming. Rotaxes can run ethanol. Some experimentals can run ethanol.
I can't speak to fuel stability.
 
CHTs are an interesting subject that made me want to explore more about the books 380F recommendation so I went to the manufacturer, Superior for the definitive word. Here is what I received back. "Never exceed the maximum red-line cylinder head temperature limit of 500F. For maximum service life, cylinder head temperatures should be maintained below 430F during high-performance cruise operation and below 400F for economy cruise operation with 300-400F optimal."

I'm not getting into one is more right than the other. I'm just sharing the facts from the cylinder head manufacturer sent to me when I specifically asked about CHT. File attached, hopefully.

For me, once I understood what Superior said about my specific cylinders I stopped freaking out about 380F+ at times after I read the book.
 

Attachments

  • CHT's for Milenium Cylinders.pdf
    46.5 KB · Views: 10
GeorgeC said:
No lead-induced valve problems.
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I had considerable trouble with valve guide wear on O-200s that I ran on Mogas. Those old designs relied on the lead for lubrication. ANd when the guide wears, the valve strikes the seat off-center and wears unevenly and starts leaking, and will burn if you run it long enough like that.
 
Dan Thomas said:
I had considerable trouble with valve guide wear on O-200s that I ran on Mogas. Those old designs relied on the lead for lubrication. ANd when the guide wears, the valve strikes the seat off-center and wears unevenly and starts leaking, and will burn if you run it long enough like that.
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As usual, thanks. No free lunch, I guess. Is there a happy medium? Can the same be expected of UL94, if it ever becomes widely available?
 
Corrosion is the biggest problem in engines that are run up and then put away. Some owners do that, think they're doing the engine some good. They're not. They'd be far better off to leave the thing alone. Fly it instead, and not for 30 minutes. More.

Catastrophic engine mechanical failure is extremely rare. You know what fails? The accessories, and they can kill you just as dead as a dead engine. From the stuff I read on this forum, many owners are running accessories to failure. Now, do you really want a vacuum pump failure in IMC or on a dark night? Do you want an alternator failure in busy airspace or when you have an upcoming IFR approach or at night? Do you want both magnetos running at their best, all the time? Do you want that engine getting lots of clean fuel, especially if the engine-driven pump fails and that ancient boost pump has to take over? Do you want the oil and fuel hoses nice and flexible and fairly recent so they aren't cracking or leaking or coming apart inside? Shouldn't all the screens in the fuel system be nice and clean? You wouldn't believe the number of times I've found screens full of crud because the strainers and inlet screens were never checked at annuals for many years.

Stuff wears out. Even if it's hours are low, it ages. It's why the airframe manufacturers publish recommendations for inspection and periodic overhaul or replacement of this stuff. These machines are not built like your practically-maintenance-free modern car. Ignore the recommendations at your peril.
 
I've been very interested in running my IO-320 lean-of-peak, but a lean test shows enough EGT variation between the cylinders that it wouldn't be helpful overall, and the fuel savings would be negligible. Contemplating GAMI injectors some day, but I currently mostly fly 65% power, out of the red box, and therefore it's kind of on a back burner for the time being. Only other thing I do that's not on the OP's list is run an engine dehydrator 24/7/365 when not flying.
 
GeorgeC said:
As usual, thanks. No free lunch, I guess. Is there a happy medium? Can the same be expected of UL94, if it ever becomes widely available?
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Lycoming updated their valve guides in 1999. They'd had lots of issues even with Avgas. Not now. Continental, I'm sure, either has plans for the same, or have maybe done it already. I don't know. I do know that there are lots of old engines out there with the old materials in them.
 
I’ve been told that Mogas isn’t the same stuff it was when the STCs were developed, and the current formulations can cause problems.

My understanding of the 400-degree limit recommendation is that At 400 degrees the strength of the metal is decreased to half of room temperature strength.
 
Dan Thomas said:
I had considerable trouble with valve guide wear on O-200s that I ran on Mogas. Those old designs relied on the lead for lubrication.
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One interesting observation I’ve made on several Continentals that have run a lot of mogas through them then get a tank or two of 100LL is that valves have a tendency to stick shortly after the switch back to leaded fuel. I’ve always assumed it is because the unleaded fuel will cause some extra guide wear then the guides get plugged up with lead/carbon from the 100LL. If I were going to operate a Continental engine I’d try to run one fuel or the other in an attempt to avoid problems.

I have not had any trouble with the Lycoming engines. 99% of the Lycomings I deal with have the newer Lycoming cylinders with the improved valve guide material though.

MuseChaser, in my personal experience after running almost 100% unleaded fuel in my Cherokee I've had no trouble and the engine health actually seemed to improve. I'd be pushing your mechanic for a little more detailed information on why he thinks running unleaded fuel is a bad idea. It's approved by Lycoming so it can't be that bad.
 
MauleSkinner said:
I’ve been told that Mogas isn’t the same stuff it was when the STCs were developed, and the current formulations can cause problems.
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Beyond just ethanol?

Some of the STCs aren't all that old, either.

My understanding of the 400-degree limit recommendation is that At 400 degrees the strength of the metal is decreased to half of room temperature strength.
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And also, the decrease in strength vs. temperature becomes nonlinear above around 400, leading to much faster wear at higher temps.
 
samiamPA said:
...can you elaborate?
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Two overhaul shops told me that some period of time after the STCs were established, the frequency of valve pounding suddenly increased where it hadn’t been a problem with Mogas previously. They finally got the fuel companies to admit that they changed the specs.
 
MauleSkinner said:
I’ve been told that Mogas isn’t the same stuff it was when the STCs were developed, and the current formulations can cause problems.

My understanding of the 400-degree limit recommendation is that At 400 degrees the strength of the metal is decreased to half of room temperature strength.
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Some engines have a 550°F CHT limit.
 
MauleSkinner said:
And they still recommend keeping it under 400.
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Keep in mind that’s a local temp. It gets hotter near the plugs and valves. So 400 there means it could be 50-70 degrees hotter in other areas.

Get things hotter...up to material limits and then the material begins to lose strength and yield.....it expands and then valve guides and seats will move.
 
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Tom-D said:
Frequent flights are better, and cheaper.

wonder why we got away without it for so long?
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Some people can’t fly as frequently as would be optimal, so Camguard is considered a good hedge.
 
samiamPA said:
This product is more for engines going into storage.

I think we're getting at the typical owner, who likes to fly frequently but might see life happen and let the plane sit for 3-4 weeks. For this person Camguard is the better option, as the antirust oil clearly states it is not for routine use.
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It does say:

"Aviation Antirust Oil is compatible with our other aviation engine oils, and may be used as a “supplement” to those products to enhance rust and corrosion protection when used in infrequently flown aircraft, particularly where high humidity is a concern. When used as a supplement, we recommend replacing up to 10% of the crankcase volume with Aviation Antirust Oil in place of the normal operational engine oil."
 
idahoflier said:
It does say:

"Aviation Antirust Oil is compatible with our other aviation engine oils, and may be used as a “supplement” to those products to enhance rust and corrosion protection when used in infrequently flown aircraft, particularly where high humidity is a concern. When used as a supplement, we recommend replacing up to 10% of the crankcase volume with Aviation Antirust Oil in place of the normal operational engine oil."
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Thanks for that. :)
 
let's think, we all know used engines varnish, so how ,much of the engine is exposed to rust?
only the portion that wears. so how long does it require to do damage?

IMHO a pre-oiler does more good than any chemical can.
 
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