How do you know you it's time for an Engine Overhaul?

spdracer888

spdracer888

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spdracer888
How do you know it's time for an engine overhaul? Aside from the obvious catastrophic failure and "interesting" noises coming out of your engine, how do you know it's time? If an A&P mechanic tells you during your annual, but what is this based on? Compression? Also how do you determine between a "cylinder/top end" versus new engine?

I noticed a lot of Cirrus have Engine well well before the 2,000 hr time: i.e. total flight time of 1,700 hours and a SMOH of 600. As I'm a step closer to aircraft ownership, I don't think I should use 2,000 as the baseline for engine reserve in my spreadsheet.

Apologize if this is a "dumb" questions...as the obvious answer is not getting through my thick skull.
 
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When parts that are inside the engine are visible on the outside(rods, piston, cam, etc). It's time for an OH.

Until then, get oil analysis, borescope, and watch the temps and pressure.
 
Compression ratios and oil analysis. .


Sent from my iPhone using Tapatalk
 
For me? Oil consumption would be the prime reason. Worn out valve guides, rings, etc. Top it? If the engine has 1200 hrs and a 1500 hr recommended limit? I'd rather overhaul. In fact I have. Ditto for a 1200 hr Lycoming with cam corrosion. Some guys would have fixed it and overlooked the rest of the engine's related issues. I have no tolerance for marginal engine condition.
 
If I had a 1,200 Lycoming O-320-E2D that needed some cylinders I would just top it and leave the bottom half alone provided it flew a lot and the bottom half was overhauled in let'say the last 10 years.

Really the answer varies a lot based on the engine history, the operator, what the plane is being used for, what type of engine it was, who overhauled it, when it was overhauled, etc.
 
Has an oil analysis helped anyone prior to engine failure? I have multiple buddies that said their analysis was fine right upto the failure.
 
danhagan said:
Has an oil analysis helped anyone prior to engine failure? I have multiple buddies that said their analysis was fine right upto the failure.
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I'm one of those.
 
danhagan said:
Has an oil analysis helped anyone prior to engine failure? I have multiple buddies that said their analysis was fine right upto the failure.
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I think that while this a great point, there is another facet to consider, which is you cannot truly quantify how many failures were prevented due to maintainance that took place due to an issue with the oil analysis. In other words, there are certainly catastrophic failures that gave no sign of impending destruction via oil analysis, but there are likely many averted due to an issue at analysis time that was dealt with.
 
spdracer888 said:
How do you know it's time for an engine overhaul? Aside from the obvious catastrophic failure and "interesting" noises coming out of your engine, how do you know it's time? If an A&P mechanic tells you during your annual, but what is this based on? Compression? Also how do you determine between a "cylinder/top end" versus new engine?

I noticed a lot of Cirrus have Engine well well before the 2,000 hr time: i.e. total flight time of 1,700 hours and a SMOH of 600. As I'm a step closer to aircraft ownership, I don't think I should use 2,000 as the baseline for engine reserve in my spreadsheet.

Apologize if this is a "dumb" questions...as the obvious answer is not getting through my thick skull.
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Clearly you consult the manufacturer. They almost always say

"...recommends overhaul after X,XXX hours of operation or XX years in service, whichever comes first"

Not a legal requirement for personal airplanes however. Nor is it a guarantee that an engine won't need major work before those recommendations. Probably 75% are passed them.
 
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A friend of mine knew when his bonanza ,with around 1500 hours on the engine blew a cylinder off over New Jersey. Hole in clouds, GPS showed airport nearby. deadsticked it in, just at dusk.
 
When you have rust like this and your oil analysis comes back with a lot of "red" levels. Of course when the crank comes back bad and the lobes in the cam are nubs that helps as well.
 

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spdracer888 said:
How do you know it's time for an engine overhaul?
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That's one of aviation's million dollar questions. Some have a far greater tolerance level than I and will continue 50% (or more) beyond TBO while still only repairing Items as they break.

Others have a far lower tolerance level and OH an engine at first signs of trouble.

I'm in the middle somewhere. I have over 1200 hours on a 1500 hour engine and have only had to rework a couple of cylinders thus far. One because of a broken oil scraper ring (that I guarantee was done at OH) and the other due to a worn exhaust valve guide.

It still runs strong. I'll likely simply keep repairing (unless it shows serious cause) until at least TBO and maybe even upwards to 2000.

My engine has never sat though and has averaged over 100 hours per year since OH. Also camguard has been used almost since day one.
 
Gosh there's a lot of misinformation on this thread! Become a disciple of Mike Busch to save money and increase safety. https://www.youtube.com/watch?v=Ts_irHU35yc

Common misconceptions:

1. You must overhaul at or near TBO (Fact: Properly maintained and flown, Cirrus and all other engines can easily go to 150% of TBO).

2. Compression is meaningful (I know this sounds crazy, but watch Mike before you respond...he's one of the top experts in the world).

3. High Oil Consumption automatically means an overhaul is needed.

4. For engine longevity, it's a good idea to land with a full rich mixture.

Do yourself a favor and read his book too:http://www.amazon.com/Manifesto-Revolutionary-Approach-Aviation-Maintenance/dp/1500209635
 
Mike Busch is all about Mike Busch. And it appears as if he's reeled you in. No one believes engines must be OH'ed at TBO...but Mike keeps saying everyone does.
 
timwinters said:
Mike Busch is all about Mike Busch. And it appears as if he's reeled you in. No one believes engines must be OH'ed at TBO...but Mike keeps saying everyone does.
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Well instead of insulting me and Mike, how about keeping it adult and constructive here. Is there some part of his theory with which you take issue?

And I disagree with your point. This is a common misconception and many engines get overhauled way too early.
 
VWGhiaBob said:
Is there some part of his theory with which you take issue?
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They've been iterated here numerous times*, including quite recently in a "Mike Busch's Mainfesto" book thread in which some folks here, that I respect greatly for their engine knowledge, chimed in.

There's no reason for me to beat a dead horse. Just suffice it to say that I respect the engine knowledge of some here, like Ted, a lot more than I respect Mike's.

*and I guess that would mean that they've been reiterated here. :wink2:
 
VWGhiaBob said:
1. You must overhaul at or near TBO (Fact: Properly maintained and flown, Cirrus and all other engines can easily go to 150% of TBO).
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Didn't know Cirrus made engines. :rolleyes:

VWGhiaBob said:
2. Compression is meaningful (I know this sounds crazy, but watch Mike before you respond...he's one of the top experts in the world).
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You can have worn rings and great cylinder compression. Oil makes a good seal around pistons. IOW, compression is a piece of the diagnosis, but not the whole diagnosis.


VWGhiaBob said:
3. High Oil Consumption automatically means an overhaul is needed.
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Really? I would thing a bit of prudent trouble shooting first. A worn out crank seal can cause the case to pressurize and blow oil out the breather. Should I overhaul the engine or replace a $20 seal?

VWGhiaBob said:
4. For engine longevity, it's a good idea to land with a full rich mixture.
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RotorAndWing said:
Didn't know Cirrus made engines. :rolleyes:



You can have worn rings and great cylinder compression. Oil makes a good seal around pistons. IOW, compression is a piece of the diagnosis, but not the whole diagnosis.




Really? I would thing a bit of prudent trouble shooting first. A worn out crank seal can cause the case to pressurize and blow oil out the breather. Should I overhaul the engine or replace a $20 seal?
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Ummmm...that is a list of misconceptions.
 
Threads are more interesting when responders offer insight rather than trying to discredit somebody else's post. I'm no Mike B fan but it doesn't offend me that some guys are, and let's face it, Mike B isn't always wrong.
 
danhagan said:
Has an oil analysis helped anyone prior to engine failure?

No


I have multiple buddies that said their analysis was fine right upto the failure.
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oil analysis tells you when it has failed.
 
spdracer888 said:
How do you know it's time for an engine overhaul? Aside from the obvious catastrophic failure and "interesting" noises coming out of your engine, how do you know it's time? If an A&P mechanic tells you during your annual, but what is this based on? Compression? Also how do you determine between a "cylinder/top end" versus new engine?

I noticed a lot of Cirrus have Engine well well before the 2,000 hr time: i.e. total flight time of 1,700 hours and a SMOH of 600. As I'm a step closer to aircraft ownership, I don't think I should use 2,000 as the baseline for engine reserve in my spreadsheet.

Apologize if this is a "dumb" questions...as the obvious answer is not getting through my thick skull.
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There is only one reason in part 91 to overhaul any engine, that is, you no longer trust it. And that is based upon a variety of reasons.
 
Stewartb said:
Threads are more interesting when responders offer insight rather than trying to discredit somebody else's post. I'm no Mike B fan but it doesn't offend me that some guys are, and let's face it, Mike B isn't always wrong.
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And they are also more boring when people rehash the same old "illigitimate positions" that have been discredited by the trusted experts here here over and over and over again.
 
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The #4 cylinder blew apart on my Gopher engine was a good sign.

Actually it was the sign that I needed to put a more sane engine on the aircraft rather than overhauling the old one.
 
VWGhiaBob said:
Gosh there's a lot of misinformation on this thread! Become a disciple of Mike Busch to save money and increase safety. https://www.youtube.com/watch?v=Ts_irHU35yc

Common misconceptions:

1. You must overhaul at or near TBO (Fact: Properly maintained and flown, Cirrus and all other engines can easily go to 150% of TBO).

2. Compression is meaningful (I know this sounds crazy, but watch Mike before you respond...he's one of the top experts in the world).

3. High Oil Consumption automatically means an overhaul is needed.

4. For engine longevity, it's a good idea to land with a full rich mixture.

Do yourself a favor and read his book too:http://www.amazon.com/Manifesto-Revolutionary-Approach-Aviation-Maintenance/dp/1500209635
Click to expand...

I didn't see where anyone said any of those things in this thread. The closest would be that compression, along with other indicators, is a factor in when to overhaul.
 
retailguy said:
Who are they and why are they "trusted"?
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Ted's #1 in my book when it comes to engines. You'll have to be here longer than two years to understand why he's trusted. (Not being a smart ass...just saying that it takes years of reading his stuff to develop the respect for him).
 
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timwinters said:
Ted's #1 in my book when it comes to engines. You'll have to be here longer than two years to understand why he's trusted. (Not being a smart ass...just saying that it takes years of reading his stuff to develop the respect for him).
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Thanks. there are a lot of people that fly below the radar and don't publicize their accomplishments. The problem with the internet is that it is impersonal and still somewhat anonymous.

I've actually spoken with and eaten dinner with Mike Busch. While I understand the self promoting machine he is, I am certain that there is knowledge there. It has helped me in the past and will help me in the future.

I'll pay attention to Ted. Thanks again.
 
spdracer888 said:
How do you know it's time for an engine overhaul? Aside from the obvious catastrophic failure and "interesting" noises coming out of your engine, how do you know it's time? If an A&P mechanic tells you during your annual, but what is this based on? Compression? Also how do you determine between a "cylinder/top end" versus new engine?

I noticed a lot of Cirrus have Engine well well before the 2,000 hr time: i.e. total flight time of 1,700 hours and a SMOH of 600. As I'm a step closer to aircraft ownership, I don't think I should use 2,000 as the baseline for engine reserve in my spreadsheet.

Apologize if this is a "dumb" questions...as the obvious answer is not getting through my thick skull.
Click to expand...

When oil analysis comes back showing I am getting into the bearing shell or other anomalies, excess oil leaking from the case (excess burning or blow by is a top end issue), obvious lower end noise like a rod knock, flat cam lobe (depending where along the OH cycle you are if you have to do a cam, the economics says do the overhaul, but can be done for considerably less as a repair), suddenly developed tracking issue with the prop and/or increase in vibration. Then there would also be occasions where I need to exceed operational limitations to bail my ass out of a bind, like busting RPM in a dive. If I know I punished an engine, I'll typically take a peek and if it was a deceleration overload, will feel better measuring the fat ends of the rods and replacing the bolts. Engines don't like being driven by the prop, especially with the throttle closed (if you have to do it hard, do it ICO and WOT for least stress, but least braking as well).

Personally, any time I'd have to split the case beyond mid time, and had any thoughts of selling within a couple hundred hours and/or few years I would complete the OH. OH is the biggest return on your aviation expense dollar. The cost of the engine prorates nearly directly to 75% TBO where it remains at core value forever until it self destructs.
 
flyingron said:
The #4 cylinder blew apart on my Gopher engine was a good sign.

Actually it was the sign that I needed to put a more sane engine on the aircraft rather than overhauling the old one.
Click to expand...

I met a cool old UFO/QB/OX5 when I was a student by helping him swap an IO-520 into a Navion on the ramp between lessons. He ended up a really good flying mentor. Spent WWII in Liberators over the Atlantic on sub patrol. That was a great flying plane with the 285hp engine.
 
As far as most owners here are novice mechanics, the advice of their A&P is the only consideration they need.
 
Henning said:
When oil analysis comes back showing I am getting into the bearing shell or other anomalies, excess oil leaking from the case (excess burning or blow by is a top end issue), obvious lower end noise like a rod knock, flat cam lobe (depending where along the OH cycle you are if you have to do a cam, the economics says do the overhaul, but can be done for considerably less as a repair), suddenly developed tracking issue with the prop and/or increase in vibration. Then there would also be occasions where I need to exceed operational limitations to bail my ass out of a bind, like busting RPM in a dive. If I know I punished an engine, I'll typically take a peek and if it was a deceleration overload, will feel better measuring the fat ends of the rods and replacing the bolts. Engines don't like being driven by the prop, especially with the throttle closed (if you have to do it hard, do it ICO and WOT for least stress, but least braking as well).

Personally, any time I'd have to split the case beyond mid time, and had any thoughts of selling within a couple hundred hours and/or few years I would complete the OH. OH is the biggest return on your aviation expense dollar. The cost of the engine prorates nearly directly to 75% TBO where it remains at core value forever until it self destructs.
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Long before you see any analysis that tells you that you are into the bearing shell, the oil pressure will be notices as very low.

Rod knocks in our little aircraft engine will last about 30 seconds before the engine will throw that rod out thru the case.

the rest of your post is an opinion of worth.
 
Any A&P with more than 2 brain cells will not except the liability of any engine that does not meet the requirements of FAR 43.2.
 
Thanks mate (and everyone else's) insightful and non-bickering comments. :)

Henning said:
When oil analysis comes back showing I am getting into the bearing shell or other anomalies, excess oil leaking from the case (excess burning or blow by is a top end issue), obvious lower end noise like a rod knock, flat cam lobe (depending where along the OH cycle you are if you have to do a cam, the economics says do the overhaul, but can be done for considerably less as a repair), suddenly developed tracking issue with the prop and/or increase in vibration. Then there would also be occasions where I need to exceed operational limitations to bail my ass out of a bind, like busting RPM in a dive. If I know I punished an engine, I'll typically take a peek and if it was a deceleration overload, will feel better measuring the fat ends of the rods and replacing the bolts. Engines don't like being driven by the prop, especially with the throttle closed (if you have to do it hard, do it ICO and WOT for least stress, but least braking as well).

Personally, any time I'd have to split the case beyond mid time, and had any thoughts of selling within a couple hundred hours and/or few years I would complete the OH. OH is the biggest return on your aviation expense dollar. The cost of the engine prorates nearly directly to 75% TBO where it remains at core value forever until it self destructs.
Click to expand...
 
Well, except that Mr. Busch tries hard to convince his followers that all A&Ps are out to screw the average owner and that they can't be trusted. That's why they need to pay him for his services...so he can protect them from from the unscrupulous A&P.

If A&Ps were honest then...

well...

????

;)
 
timwinters said:
Well, except that Mr. Busch tries hard to convince his followers that all A&Ps are out to screw the average owner and that they can't be trusted. That's why they need to pay him for his services...so he can protect them from from the unscrupulous A&P.

If A&Ps were honest then...

well...

????

;)
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You don't need to know everything, but life sure is easier if you know enough to know when you're getting ****ed.;)
 
Henning said:
You don't need to know everything, but life sure is easier if you know enough to know when you're getting ****ed.;)
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And if it is hurting while you are doing it, you are doing it wrong! :yikes:
 
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