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How to Preserve a Lycoming for a few months - help!

My PA28 is in the paint shop but is taking a little longer than expected. I was planning to run a closed loop engine dryer but this particular device has broken down so I need to find another way to preserve the engine for another 4-6 weeks fast! Another factor is that the engine oil was drained last week.

It has dehydrator spark plugs installed since it went in and the inlet/exhaust ports are sealed. I am mainly worried about the camshaft as this is exposed, however, as the oil has been drained, everything is now exposed. It is not possible to run the engine with preserving oil as per the Lycombing instructions as the Aircraft is now spotlessly clean and almost ready for painting. It has been sitting for 4 weeks so the oil flim/camguard would have disappeared by now so I have to act quickly. See Lycoming instructions [ local copy ]

When I used to go water skiing, I used to lay up the boat engine with Quicksilver fogging oil

I also found this online

These volatile preserving oils seem like a good solution. If I can’t get the engine dryer working properly I plan to put in 8 quarts of engine oil to protect the crankshaft bearings and spray in a can or preservative oil through the dipstick.

Can anybody see a problem with this idea? Could it possibly attack any seals? Any other ideas?

United Kingdom

A Lyco engine has no parts immersed in oil, except bits of the oil pump I think. The crankshaft is not immersed in oil. The whole engine is pressure lubricated. When it stops running, all the oil runs off down into the sump. This oil runback takes several days to take place, in terms of the last 5mm or so on the dipstick.

Camguard will remain as a coating on everything.

6 weeks should be fine, indoors, in a hangar whose temp is at least a few degrees C above the outside, if you used Camguard previously.

Shoreham EGKA, United Kingdom

Thanks Peter,

That makes sense as nothing being immersed as there is a big sump underneath. I suppose the crankshaft never has issues as surface tension between the crank and the plain bearings keeps the surfaces coated.

Yes, I always run with Camguard. We are at the 5 week point now and waiting for windows which were promised with a 4 week delivery but could be 8 weeks, then there is Christmas + other delays. I can see mid January as being realistic. I don’t like the idea of 2 1/2 months standing about when it has never sat for more than 3 weeks in the lifetime of the engine.

Any ideas about fogging oil anybody?

United Kingdom

Peter wrote:

in a hangar whose temp is at least a few degrees C above the outside,

Yes, that’s a key point. It’s difficult (impossible?) to find a better corrosion inhibitor than that. In a paint shop, both humidity and temperature are important. I can’t imagine they would ever let the relative humidity increase to the condensation temperature. The thing to remember about corrosion is three elements have to come in contact with each other simultaneously: A substrate to corrode (metal), oxygen (air) and an electrolyte (liquid water with some ions, salt). Remove one of those, and it won’t corrode. It’s as simple as that.

The elephant is the circulation

It is in a hangar where it is being prepared, not in the heated paint shop. There are delays due to some repairs and waiting for the new windows etc.

My understanding of this issue is not that good as I normally fly weekly so have never worried in the past.

However, surely there is/was water in the engine from combustion products which will cause a slow deterioration. Let’s just assume that the the relative humidity inside the engine after shut down was 90% ++ (People often report steam coming out of the oil filler on shutdown). Are you and Peter saying that after 4 weeks the RH of the engine will be the same as the Hangar as it is not perfectly sealed, hence the water vapour escapes and equalises to outside humidity?

Without drying the engine or coating the metal with an oil film, what would stop rusting? Also as I have drying plugs with Silica gel and as vapour leaks past the piston rings is this sufficient to dry the internals of a well sealed engine?

United Kingdom

If possible, check it’s still inside.
I’ve twice had evidence that a wood-and-fabric tailwheel aircraft had been left outside for weeks when some part needed at an Annual was not immediately available.
On one occasion, after I’d flown it back on a dry day, water poured out of the tail after landing. )-:

EGPE, United Kingdom

I would go for the following:

to comply with the instructions in the Lycoming service letter local copy

It doesn’t cost much in the grand scheme of things compared to inadvertent shortening of an engine lifespan.

EGTF, EGLK, United Kingdom
Well, I do not run that type of engine but I do not believe in a reason for panic about corrosion due to some weeks or months of non-operation – provided the last flight was at least half an hour to boil off any condensation in the engine or oil sump. You will see a level of temperature in the oil and case in flight that will not hold any relevant quantity of water for very long. Condensation is blown out into free air all the time through the breather so how can the engine collect water ?? The ominous cam problem with Lyco engines is NO rust problem as I see it. Instead it is a matter of choosing an engine oil that does NOT drain a lot when the engine is stored for longer periods : A multigrade is the worst you can do to the cams, they will be pretty dry in some months. Camguard is most likely just some sticky additive like the olden STP honey that sticks to cams when oil has long drained down. There was this thread recently showing cams and followers with excessive wear BUT not a trace of rust anywhere close on other components so I do not follow this rust religion in Lycos :

Lyco cams

But the real root of the problem is the poor design of cams and followers, not exclusive to Lyco but also found in old BMW bike flat twins, Ford V 6 and some more I think: The idea was foremost to provide some rotation for the followers by offsetting them relative to the cam lobes. The designers went for slightly convex follower faces paired with lobes that are ground tapered, the cam grinding wheel dressed at about one degree taper. So in effect the lobes are 0.10 mm higher at the off side opposite from the follower and offset at the same time – as shown with BMW parts in my pictures. The result in operation is a contact patch between lobe and follower that is not even a line but some curved wear shape at minimal size so the oil is VERY challenged to keep friction faces separated in use. The wear on lobes is always maximum at the one higher taper side, not all along the full width , see pictures . When you look closely you can see the ridges where the contact patches end. No surprise that an almost dry cam lobe will wear in short time depending on the kind of material that is paired for cams and followers. Why that shape was chosen for lobes and followers is not clear to me at all: When you look at engines with dohc heads and bucket/cup tappets and their shims for setting valve clearances you will NOT find convex buckets or taper ground cam lobes – and still there is sufficient rotation of buckets by only offsetting lobes and dead flat buckets, no wear due to great full line contact patch. So that really says to me the Lyco troubles with cams are simply overloaded components at minimal contact patches and no oil remaining in long periods of storage, not a rust effect. The camguard additive to multigrades may be helpful , the W 100 monograde is better but a pain in cold weather for starting, so W 80 for winter use. Vic


Hmmm, you are 100% right, Vic. This is an IO540 cam follower:

Camguard does work however. That link is worth a read. The poster “Ed” is the Camguard inventor.

Shoreham EGKA, United Kingdom

Thank you all for some great responses especially the last two from @vic and @Peter. My closed loop dryer is working again so humidity inside the engine is 16% and falling which is good news. My understanding is that:-

  • My weekly flying is always a minimum of 45 minutes and as oil temperature goes to normal, this allows any water in the oil to boil off. However Engine humidity is always 100% after being run every time – this is bad but see below.
  • Lycombing say that when you give the engine a 45 minute plus run, flying under load, this allows an oil varnish to coat the critical surfaces.
  • A short ground run (where the oil does not get up to temperature) does more harm than good as the oil ends up with water in it and presumably not enough enough time to glaze the surfaces.
  • Also people who “hand turn” their prop a few revolutions (in the hope that some oil will pump onto the cam), also do more much more harm than good as they scrape any remaining lubrication off the cam/ cam followers
  • I always thought that when the rust layer occurred on the cam/cam followers, these tiny imperfections caused excessive wear on the very thin hardened layer on the metal surface.

So @vic, you have a really interesting post and photos of why the cams wear so quickly (poor design and lots of loading in a small area), but my question to you is perhaps the microscopic pitting in the hardened layer is the gateway to excessive wear?

Perhaps you would never see the rust but this allows a rough enough surface to start these problems. Also when the hardened layer has worn through then things go downhill fast?

So my question, is the real issue (a) water (rust) or (b) lack or oil that is worst? Or a bit of both?

United Kingdom
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