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Engine hours


FastTex

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Hello,

I saw a 1967 Mooney E, she overall looks good. I'm puzzled about the same thing that lots of people ask: the engine has about 500hrs SMOH done in the mid 90s. That makes it about 23hrs/year of flying. I have not seen the logs, so I do not know how the hours are distributed but I do know she has been flown some hours in the last few years. What concern should I have about corrosion inside the engine? Does investing in pulling a cylinder answer the question?

I appreciate the feedback and help.

Tex

 

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Lycomings have them am up high.  If it sits for a long period of time, the oil drips off of the cam, so is not lubricated for the first few seconds of the next startup.  As I understand it, the only way to inspect the cam is to pull a cylinder.

Theree is an additive CAMGUARD, that can be used in the oil to make the oil stick to the cam longer before draining off.  I understand that the Shell oil with PLUS at the end of its name has this additive already in the oil.

Hope this helps.

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Imho, there is hardly ever a good reason to pull a cylinder when it's just curiosity that's driving the decision. And peeking in the crankcase normally won't do a bit of good to confirm or deny that there is any real problems.

I would pull the plugs and borescope it, and then ask - Does the engine run ok? Is it making book numbers in flight? Are the temps and pressures correct? Is it burning between 1 and 2 quarts every 10 hours? Are all the hoses and connections sound? Is it vibrating or making any strange sounds?

If all is good, I'd fly it like it was new.

I would also add an oil analysis to every change to look for trends

Others will likely have a different opinion, but weigh the pros and cons of pulling a jug carefully.

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25 minutes ago, DVA said:

Imho, there is hardly ever a good reason to pull a cylinder when it's just curiosity that's driving the decision. And peeking in the crankcase normally won't do a bit of good to confirm or deny that there is any real problems.

I would pull the plugs and borescope it, and then ask - Does the engine run ok? Is it making book numbers in flight? Are the temps and pressures correct? Is it burning between 1 and 2 quarts every 10 hours? Are all the hoses and connections sound? Is it vibrating or making any strange sounds?

If all is good, I'd fly it like it was new.

I would also add an oil analysis to every change to look for trends

Others will likely have a different opinion, but weigh the pros and cons of pulling a jug carefully.
 

If i would have an engine that only flew 23 hours per year for the last 20 years or so , i would be very curious about it's condition , Pulling a cylinder is not a bad idea . First  i would warm it up , let it run at high idle for a little time and pull the oil and the filter and inspect for metals . Never mind the cylinder condition at first , i would like to know if this engine is making metals , or had made metals . 

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I would be more concerned if there were a number of years where it was much less than 10 hours between annuals.  If the plane was flying 12 or more hours a years you probably have no more worries than any other engine.

Get a good pre buy inspection and if it goes well and the overall price is right pull the trigger.  Will you have some surprises after even with that approach yes you will but once you have it fly hours a year on it.  Cost wise after you get past annual inspection, insurance and tie down you are only paying for fuel to fly the next hour.

Pull a cylinder only if necessary.  There is a thing called maintenance induce problems.

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You're right about the distribution being more important than the hours. There are years my Mooney has only gotten 23 hours as I fly other toys.  But that's an hour every 2 weeks and that's fine for an engine. It's the guy who puts a couple 10-20 hour vaction flights a year and then sits you need to worry about. 

-Robert 

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2 hours ago, DVA said:

Others will likely have a different opinion, but weigh the pros and cons of pulling a jug carefully.

Agreed. You might just have the oil suction screen pulled. More than likely, the last few oil changes this wasn't done and if there is a place to look for cam parts, this is a good place to start.

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If i would have an engine that only flew 23 hours per year for the last 20 years or so , i would be very curious about it's condition , Pulling a cylinder is not a bad idea . First  i would warm it up , let it run at high idle for a little time and pull the oil and the filter and inspect for metals . Never mind the cylinder condition at first , i would like to know if this engine is making metals , or had made metals . 

This, but I would take a couple of loops around the pattern, I want see it at 2700rpm, I want to see the landing gear in action, quick check of the expensive avionics, especially the autopilot if it has one.
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Engines are a crapshoot.   You could pull a cylinder look around and it may still eat a cam in first hundred hours.   Do a compression test on it.   Look for other things that suggest how or how not to price the engine like the annual inspection hours accumulation.

Where did it sit.  

When were the last time the mags looked at?   Plastic gears, capacitors with majic smoke

The spar and roll cage are the big gotchas.   Pull the seat, Pull the most inboard, most rear inspection panel on the wing and look around.

 

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have $10K in the bank to fix things the first year.

fix Accutrac system 2000

new hoses 1100

tires 300

engine mags 2500

An accessory or two 2000

new cylinder 2000

Oh and you can also post the plane here and the peanut gallery will be happy to give their internet opinion

Edited by Yetti
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Thanks All for the great info and suggestions.I have just received a few more details:

- Last three years flight time about 50hrs

- Overhaul completed in the "early" 90s

- Price is right on vRef (about $45k)

It means the airplane has been flown about 22 hrs/year (assuming SMOH is 1992), for 22 years, until three years ago, then about 17hrs/year since then. At this point I'm not even sure it is worth the pre-buy investment unless the price goes way down...pulling a cylinder is not cheap.

Thoughts? 

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The only way to see the cam on a four cylinder Lycoming is to remove a cylinder or two.  On the larger Lyoming engines a portion of the camshaft and a few lifters can be seen by removing the oil filler tube from the top of the engine and inserting a borescope.

If the purchaser doesn't want to spend the money for the inspection, he shouldn't expect much pity if the engine has corrosion related issues on his watch.

Clarence 

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Pulling a cylinder is nice from the buyer's perspective, but Mike Busch is not a fan because you can screw up bearings if not careful.  This is why he is against pulling cylinders for overhaul simply because of lowering compression.  I think it has to do with the fact that the through bolts holding the cyls on also have an effect on alignment of the engine case.

 I really would not, as a seller, allow someone to pull a cylinder just for a peek.  It's considered very invasive.    You're better off with a lowball offer, fly the heck out of it and take oil analysis / monitor for metal.    Use the savings to help rebuild the engine if the time comes.  Sellers need to know that they place their engines at risk when they don't fly, and they will take a hit when it's time to sell because of it.  I think I'd rather buy a higher time engine flown regularly than a low time one that has been sitting.  In the latter case, you don't know if the camshaft will start spalling as soon as you buy it, or 300 hours down the road.   

I would try to get a look at logbooks and figure out the distribution of the hours in the low years.  Take an oil sample, and see if any of the wear metals are way out of a normal range.   Look inside the screen or the filter, and the suction screen.   At least you can find supporting evidence for your decision in a manner that the owner would likely allow.

Such a shame that people let their planes sit for so long before they realize they should sell.

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So if the seller is reluctant to allow the purchaser to remove a cylinder to verify the health of a long sitting engine.  But would be willing to accept a low ball offer based on the same corrosion concern.  

If I were the seller I would agree as long as the cylinder was being pulled where I have control of the process.

Clarence

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Do not put anything more than core value in a engine that is 20+ years old. NOTHING. Even oil with 10 hours of run time is corrosive if sitting long enough. Pulling a cylinder is a terrible idea. Pulling two would make more sense from a inspection stand point because it's possible and very likely that one cam lobe/lifter is in the early stage of failing but another cylinder aft or fwd of it looks beautiful. But now pulling two cylinders exposes more than double the risk factor of engine failure due to invasive maintenance. No way would I pull any jugs. If the buyer wants more than core value then the air frame or avionics need to be discounted deeply but the 1/3 engine, 1/3 airframe and 1/3 avionics value to arrive at the purchase price still needs to make sense. My guess is the engine will make metal within 50-100 hours so if it can be bought at the right number I'd fly it straight to Jewell to have him save what parts he can before the metal filings prematurely take out good parts.

 

 

Sent from my iPhone using Tapatalk

 

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I just got another piece of information: the airplane was re-painted and interiors redone in 2014 (this is why she looks so good...on the outside), flew 50hrs for three years and now it's for sale. Is it me or this sounds "fishy"? At the same time who would spend all this money for paint and interiors if the engine is no good?

Edited by FastTex
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Price it as if it has a run-out engine and then make an offer.  See if the seller accepts and then go from there.

An airplane that sits is not guaranteed to need an overhaul, it just makes it more likely.  There's randomness to it.

I bought an airplane that only flew a few hours a year for the last 4 years.  After putting 150 hours on it in the last 18 months, compressions and oil burn all remain perfect.

I also know a story of a guy who overhauled his engine, flew it regularly, and then it ate a ring at 150 hours and needed another major overhaul.

It's a $20k gamble that all airplane owners have to make.

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