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eng compression

D

drmax

Well Known Member
Hello. I've read a bunch, now will reach out here for opinions. I'm looking at a craft with 0-360 with c/s prop. Eng 12 yrs old. Time since new, 400 hrs.
It's lived in GA its life, and has flown regularly. Compressions on all cyclinders are mid 60's. I can't listen for air leaks anywhere, as I'm not there. The checks are performed by an AI. I do have another individ. lined up to do compression ck, boroscope, and oil analysis, of course for a chunk of change. My question to you...what are the odds it needs engine work? They are gonna run it and do another comp. test. This AI states...."those are good readings". (mid 60's) That throws a flag in my mind, questioning the integrity of that AI.
DM
 
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If the check is done cold then they might be fine. I would try and get a check done after the aircraft has been flying. I think those meet lycomings standards however I would not be happy. It might also be a point in price negotiations. New cylinders have come down in price. You might price out a set and try and get half the cost off the purchase price.

George
 
ok

sailvi767 said:
If the check is done cold then they might be fine. I would try and get a check done after the aircraft has been flying. I think those meet lycomings standards however I would not be happy. It might also be a point in price negotiations. New cylinders have come down in price. You might price out a set and try and get half the cost off the purchase price.

George
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they're gonna ck again, after running, like 30 minute flt. if they can't not listen, for where there may be a leak...then I don't think they know what they're doing...and I don't want the headache. If they ck and compressions are up, then I may proceed. You'd think his mech. would have put an ear to it, by now. unreal. thx for the reply
 
The plane needs to be flow full throttle for a short while, then whipped into the hangar, cowls off and do the leak down.

A Leak Down is not a very revealing test. It really only guides you into looking further if something is bad.

The next thing is a boresecope which you should get the images emailed to you, post them here or to me if you like.

There may be small corrosion marks from not being flown enough, but that does not condemn the engine however it may mean slightly lower leak downs and slightly more oil consumption/blow by, but nothing that is terminal.

If it is the right airframe, and the right price, then proceed.
 
drmax said:
Hello. I've read a bunch, now will reach out here for opinions. I'm looking at a craft with 0-360 with c/s prop. Eng 12 yrs old. Time since new, 400 hrs.
It's lived in GA its life, and has flown regularly. Compressions on all cyclinders are mid 60's. I can't listen for air leaks anywhere, as I'm not there. The checks are performed by an AI. I do have another individ. lined up to do compression ck, boroscope, and oil analysis, of course for a chunk of change. My question to you...what are the odds it needs engine work? They are gonna run it and do another comp. test. This AI states...."those are good readings". (mid 60's) That throws a flag in my mind, questioning the integrity of that AI.
DM
Click to expand...
DM:

Think about it... The engine is 12 years old... Lycoming recommends a Major at 12 years.
The plane has ONLY flown for 400 hrs in 12 years... Am I reading you correctly? That is only 33 Hrs per year IF it was that much per YEAR and had not sat for a few years.
Mid 60's.. Mid 60's like 63 to 66 PSI... Acceptable but not great.
NOW! What does the PRICE reflect? If the price is low GO- FOR -IT!
BTW - Compression's will change with every flight. Fly it more and you may see an improvement.
Oil Analysis - My Opinion - WASTE of TIME and Money. Spend the money on a oil change. And if you are going to fly the plane a lot... Just use Mineral Oil (M20W50) for the next 10 hours and do another compression check. I'd bet you have rust in the barrel and the rings are not seating.

Barry
 
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Compressions

I bought a 172 with similar compressions-really wanted the plane. Next annual, compressions were lower, bought new cylinder, found out when apart that the cam lobe was worn beyond tolerances and resulted in a major overhaul. This was an extreme case of what can go wrong but was my experience on a mid-time engine.

Good luck.
 
Barry_Barry said:
DM:

Think about it... The engine is 12 years old... Lycoming recommends a Major at 12 years.
The plane has ONLY flown for 400 hrs in 12 years... Am I reading you correctly? That is only 33 Hrs per year IF it was that much per YEAR and had not sat for a few years.
Mid 60's.. Mid 60's like 63 to 66 PSI... Acceptable but not great.
NOW! What does the PRICE reflect? If the price is low GO- FOR -IT!
BTW - Compression's will change with every flight. Fly it more and you may see an improvement.
Oil Analysis - My Opinion - WASTE of TIME and Money. Spend the money on a oil change. And if you are going to fly the plane a lot... Just use Mineral Oil (M20W50) for the next 10 hours and do another compression check. I'd bet you have rust in the barrel and the rings are not seating.

Barry
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what is low? c/s prop...same age. ifr, one steering servo trutrack, slider canopy, 7 on paint job/interior, elect. flaps/trim, leading edge landing lts. (pnl is older)
I have thought about the 12 yr issue. And I'm wondering how to get the compressions higher. i'm not about to buy this, just to stare an overhaul in the face.
 
John Owen said:
I bought a 172 with similar compressions-really wanted the plane. Next annual, compressions were lower, bought new cylinder, found out when apart that the cam lobe was worn beyond tolerances and resulted in a major overhaul. This was an extreme case of what can go wrong but was my experience on a mid-time engine.

Good luck.
Click to expand...
I'm assuming the eng had higher time on it, though for cam to be worn?
 
engine compression

many lycoming o-320 engines reach 20 years in service or even 30 to 40 years in service before they reach 2000 hours since new.(and need a major overhaul)

i have never understood lycomings "overhaul at 12 years" statement.

every engine is different.proceed accordingly.

good luck. and enjoy the hunt.
 
lawrence said:
many lycoming o-320 engines reach 20 years in service or even 30 to 40 years in service before they reach 2000 hours since new.(and need a major overhaul)

i have never understood lycomings "overhaul at 12 years" statement.

every engine is different.proceed accordingly.

good luck. and enjoy the hunt.
Click to expand...

oh yeah, and while i have 'yalls attention...if you know of a 6A for sale, send me a PM.
 
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