Sorry these aren’t great. It was the first time using the new borescope. I was able to spot one cam lobe through the filler neck, then i scoped a few cylinders but not all. I was kinda being rushed by a group dynamic, not the seller. Also the engine was hot and the scope kept going into overheat mode.

The seller has been running Aeroshell 15w50 for ten years. But the aircraft hasn't flown in a full year until yesterday. Prior to that it was 3-4 hours per year. 200 hours since 2013. Cam is an overhauled part.

Seller also admitted that he starts the aircraft and warms it up periodically, but doesn’t fly it. Presumably to coat the engine innards with oil, but as we know, that’s one of the worst things you can do to an engine that sits.

Engine runs strong in flight. Warm compressions are all between 73/80 and 79/80. Storage is in a very dry southwest climate.

Thoughts?

That one lobe looks great, but I think we can all agree that it has run a less than optimal amount for the last 13? years. IMNSHO this should have a significant effect on engine value.

Personally I worry a lot more about the bottom end than cylinders.

Zane,

Run away!

Seriously, I would not pay more than core value for this engine. I would not trust it without a tear down and if you tear it down you might as well overhaul it. Are you planning on putting your kids behind this engine?

In my opinion he has done everything wrong in preserving this engine. He may have had good intentions. Very good chance its going to have issues.

Damaged camshaft lobe(s) & tappet faces typically do Not show up during compression checks but can often be identified by comparatively measuring valve lifts with a dial indicator (compare intakes & exhausts separately).

Tho it might be an artifact of the lighting, the surface of the cam lobe apex appears distressed (slightly spalled) in one photo.  Cam spalling does not self-correct with continued service.  Tho the engine will likely run, its volumetric efficiency and thus power will decrease as lobe & mating tappet spall and lose material.  My bigger concern would be the associated tappet, which cannot be removed for inspection without splitting the crankcase. 

I have not seen a camshaft break due to worn lobes, but I have seen multiple instances of spalled tappet breakage, sometimes with collateral damage as the piece(s) drops and plays pinball with the rotating bottom end.

Fly safely.

Any logs or yellow tags?

Borescoping is a true work of art. So don't be too hard on yourself. Watching the videos I've made trying borescope on the turbines could make a guy sea sick. haha.
I would say that the lobe doesn't look too bad to me. I agree with Pat that it would be nice to see what the face of the tappet looks like. But he really did everything wrong as far as preserving the engine goes, and it will most likely have issues coming. The price should definitely reflect that.

I think it's human nature to find negative things any time someone posts borescope pics, it's like a dopamine hit to spot the bad stuff or something.
Does look like a tiny bit of spalling on the cam lobe, but not an alarming amount to me. Cylinders don't look to have much of any cross hatch left. Valve seats can be lapped in place if needed, but if it's making compression and no scary heat signature on valves I'd run it.
No significant running in last ten years I'd be looking at changing rubber out(intake boots, oil return lines, oil pressure line etc.) as preventative mx, but metal wise I'm not seeing anything just on these pics that I wouldn't run.
Was 2013 the overhaul? I would guess those parts have a fair bit north of 200 SMOH
Edit to add - I'd echo that price should reflect ground runs and lack of time likely leading to additional needed Mx in future.

Any time you buy there is risk that it wasn't treated well or the previous shops were staffed with monkeys or there is a failure right around the corner, so I think the first step is to collect data and consider the risk we are dealing with.

In this case, the engine was plainly neglected, but given those pictures and good oil pressure and compression test, I don't see anything that will kill you, so the risk of it failing out of the air is probably low. The next thing to consider is if you have a some part that is getting ready to fail like a cylinder or cam or something, in that case the way to mitigate would be having reserves on hand to deal with it....

In this case, I'd probably offer $30k less than what you believe the airplane is worth, and if the seller takes it, fly it for a bit and get some operational history on it while monitoring for metal, compressions, etc. You may find that the engine is fine and get lucky, or you may find it takes all $30k (or more) to fix it. The idea is that you pass the mitigation to the seller, and see how lucky you are.

Another risk to consider is the possibility of having another project. If it does need a camshaft and a few cylinders you will need to have that $30k on hand to immediately deal with it otherwise it will turn into one more non-flying airplane to add to the pile. In your situation it's probably not worth it, just buy something that doesn't need anything.

At risk of sounding unlearned, what's wrong with periodically running the engine? I thought that was helpful to preservation, presuming you get the temps hot enough to evaporate water.

twofingers wrote:At risk of sounding unlearned, what's wrong with periodically running the engine? I thought that was helpful to preservation, presuming you get the temps hot enough to evaporate water.

If your anticipating an extended period of storage its far better to properly inhibit the engine than running it occasionally, just the cooling down after an engine run will generate moisture. Every time you run the engine the cylinder walls are scraped bare of oil and exposed. Even seasonal temperature fluctuations will generate moisture on a surface or within a space. If properly inhibited and left along the internal bits & pieces are protected. Additionally you can use dehydrator plugs in place of spark plugs for moisture control as well.

akscu is on point.

While everything the rest of the gang suggests is conventional wisdom, it's also all anecdotal at best.

Not long ago, we all treated these engines the way we did because it's what grand dad did. Today, with modern instrumentation, we find a better way. Yes, most of the conventional wisdom still rings true. Experiences do count for something, but now we can do infinitely better and consequently expect better outcomes.

The obvious fear with respect to Lycomings and infrequent operation is cam surface rust, which subsequently leads to spalling, leading to metal sanding your engines' innards away. That is not evident in the little you have here.

If you are trying to be as fair as humanly possible (rare in business transactions) or want to be as educated about the engine as possible with the means you have available you need to revisit it without the rush.

If otoh you want to be as fair as possible within reason, I'd suggest treating the engine as a core. Intentional or not, it is what the PO did.

If you elect to move forward, I'd not run it without either a through
inspection, or iran. Odds are still good there is rust you just didn't find, and running will generate that liquid polishing compound.

A gentleman who's fleet of true antiques I had the privilege of keeping exercised had examples that would see months and some even years between joy rides. None experienced catastrophic failure, but most experienced leaks from dried seals, sealants, or hoses.

Anecdotal from the opposite side of the coin.

Take care,
Rob

One more part of the puzzle is that storage is in a very dry area of the southwest.

And the reality is that you have been looking for a while for the perfect bird. If it ticks enough boxes and the price is reasonable considering some engine risk, maybe take a punt? Its nice to own an airplane even if there are occasional "what the hell have I done" moments. We all hear the times a poorly preserved engine fails, but there are maybe a lot more that run just fine and leak a bit here or there.

Zzz wrote:One more part of the puzzle is that storage is in a very dry area of the southwest.

Is the engine a preferable wide-deck model i.e. are the cylinder base flanges secured with hex nuts (wide-deck) or internal wrenching fasteners (narrow-deck)?

Everything else pictured in the bottom end looks clean enough to buy, in my eyes.

Lot of good comments here, save for I don't get a dopamine hit when finding anomalies, borescope or otherwise.

Establishing an engine-oil wear-metals baseline then resampling periodically to confirm Iron - & other metals - are not increasing markedly is a worthwhile idea. Lycoming's
https://www.lycoming.com/content/service-instruction-no-1492d (title is a bit misleading; there is much good info within)
&
https://www.lycoming.com/content/service-letter-no-l171
refer.

iPat wrote:Is the engine a preferable wide-deck model i.e. are the cylinder base flanges secured with hex nuts (wide-deck) or internal wrenching fasteners (narrow-deck)?

Yes, it’s a wide deck, and injected. i currently own two narrow deck Lycomings so I suppose i will need to buy a new set of cylinder base nut wrenches.

It is all about the level of risk one is willing to accept and how (if at all) they elect to mitigate that risk. With a properly structured oil analysis program combined with continued diagnostics (compression/borescope) this engine may run to TBO and beyond, and, you guessed it, it may not. However, the probability of catastrophic failure is low enough to barely register a concern. With proper continued diagnostics (warranted due your description of the engine), you should be forewarned by those diagnostics of increased wear leading to impending failure if ignored.
It may sound silly, however, another risk mitigation tool for a candidate such as this is limit it to float ops and stay within gliding distance of water. Extreme? Perhaps, however, it depends on one's specific operations and environment and ultimately, risk tolerance. Just another risk mitigation technique.

TR

So, with all the advice and opinions offered, are you moving ahead with this purchase, or continuing your search?

Those are some odd pictures, I am not super happy about the spalling on the cam lobe, as others have said if you can see this damage what does the bottom of the lifter look like? The one pic of a cylinder wall still shows crosshatching which would lead one to think it is low time or very good condition. The others however show a concerning amount of striations running vertically up and down the cylinder walls. To me this is showing a high incidence of wear, possibly from ring issues or from crap falling off the valve faces and or cylinder head.

All in all, this doesn't look like a real happy engine to me. It might work just fine for a long time and it might not. Nothing I see says KABOOM! in the next ten hours but without doubt it is going to need some love at some point.

Thanks for the input, all. I have decided to pass on this one.

Fun to see all the responses. I encourage others to post similar photos for the benefit of the braintrust.