is 77, 75, 78, 65 compression in a LCO O360 a prob

[tomcat27]

is 65 psi compression in one cylinder of a Lycoming O360 a problem?
the plane/engine has approx 500 hours SMOH; and I saw "78/80" written on the valve covers each day during pre-flight; so I wasn't concerned. of course, having to add two quarts of oil in 15 hours of flight didn't make sense to me, so we pulled the maintenance records. the recent annual showed 77, 75, 78, 65. all prior annuals showed all readings in the 75-80 range. to me this is a red flag!!! why didn't the mechanic have a concern?

I also find the whole concept puzzing: most private plane engines (Continentals, Lycomings) are 1950's technology: low RPM (2600 redline in this one), low compression. I know that "reliability" is the goal; but really?!?!?!?

 

[maxdustington]

Mechanic is a BITOGer and is currently trying 20W50 mixed with some power bait to get that compression up

 

[tomcat27]

true, there is 66 20w50 in there... there was a sticker (not an OEM sticker) on the engine calling for 70W
I wish I'd known about the low compression before flying it! and the recent throttle cable break was kinda scary!!! and the radio failure last year! I also have a new-found fear of birds. and since when do birds fly @ 5000 feet AGL???

 

[CT8]

Originally Posted By: maxdustington
Mechanic is a BITOGer and is currently trying 20W50 mixed with some power bait to get that compression up
Power bait is might fine stuff.

 

[BrocLuno]

I'd wanna know why it's 65 PSI ... Broken rings, bad scratchs in the cylinder, what's goin on. Dry/wet test and a pressurized leak-down at TDC and BDC will tell more. Also looking at cylinder walls with a bore scope would be good.

 

[Billbert]

What is power bait?

 

[maxdustington]

Originally Posted By: Billbert
What is power bait?


http://www.berkley-fishing.com/berkley-powerbait/

There is a legendary BITOG thread about some dude who "accidentally" had a power bait fall in his oil fill and asked for advice.

Can someone please find that thread and link it? I read it once a long time ago, but I don't even know what to search for besides "power bait"

 

[CT8]

Originally Posted By: Billbert
What is power bait?
Bait for fishing . There was a poster that "by accident " had some power bait fall into his engine.

 

[CT8]

Originally Posted By: Billbert
What is power bait?
link to BITOG post about powerbait.

 

[maxdustington]

Originally Posted By: CT8
Originally Posted By: Billbert
What is power bait?
link to BITOG post about powerbait.


CT8 you are awesome, BITOG was fun to read when the trolls were around.

 

[Yah-Tah-Hey]

Originally Posted By: tomcat27
is 65 psi compression in one cylinder of a Lycoming O360 a problem?
the plane/engine has approx 500 hours SMOH; and I saw "78/80" written on the valve covers each day during pre-flight; so I wasn't concerned. of course, having to add two quarts of oil in 15 hours of flight didn't make sense to me, so we pulled the maintenance records. the recent annual showed 77, 75, 78, 65. all prior annuals showed all readings in the 75-80 range. to me this is a red flag!!! why didn't the mechanic have a concern?

I also find the whole concept puzzing: most private plane engines (Continentals, Lycomings) are 1950's technology: low RPM (2600 redline in this one), low compression. I know that "reliability" is the goal; but really?!?!?!?
The "mechanic" is probably a Spartan grad.