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CT2K

Lower compression after oil change

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CT2K   

This week I got my oil change done at the ULM club. The guys changed the oil, oil filter and spark plugs. I flew something like half an hour after the engine was serviced and noticed the following three points:

- After the 30 minute flight I let the engine rest and then turned the propeller manually to gurgle and gauged the oil. It showed nearly one cm above Max level. Is that bad, or dangerous, or shall I leave it because it won't stay there all the time anyway?

- Turning the propeller manually I also noticed there was les compssion in the way that I felt far less resistance than before the oil change. Indeed, the propeller now turns much easier and smoother manually.

- Last thing I noticed was that during takeoff the engine showed way less nerve and climb rate was low compared to before.

 

Any clues as what all that can be due to, and how best to recover the brilliant behaviour the engine had before the oil change?

 

for information the engine has 600 hours.

 

Many thanks for stopping by and for sharing your valuable thoughts.

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CT2K   

Burped warm as well as cold and the difference with before is there in both cases and it is definitely clear.

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Oil levels lie. Yours is fine. High oil level in a dry sump is no big deal. It could be lower another day or the people that changed the oil failed to burp the engine well before the change and a little more oil than normal was left in and not drained.

Many times different perceptions in performance without real numbers and exact same flight conditions are just perception and not real.

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CT2K,

A significant reduction in torque needed to hand prop the engine and a noticeable reduction in spunk during takeoff could both be explained by a couple loose sparkplugs. Maybe the folks who did the maintenance for you forgot to tighten the plugs on the bottom of one side. Though improbable, it might be worth putting a wrench on all eight just to make sure.

Mike Koerner

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CT2K   

Gentlemen, many thanks for all your valuable contributions. Will explore the lose sparkplugs route.

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CT2K   

Given you took the time to kndly share your thoughts, I thought I owe you this little update/feedback:

Measurement of sparkplugs tightening showed they were not loose.

The guys at the club did the oil change and tightened the new sparkplugs to 20 N when the engine was still warm (very warm actually) so now and when engine is cold sparkplugs show they are tightened even higher than the recommended 20N.

the thought around here about compression diffrerence may be due to oil difference. The CT was bought second hand so we don't know what was the previous oil. The oil used for the change is Yacco. They used 2 litres of this one:

https://www.yacco.com/product/222-avx-500-4t-sae-10w40/

and they topped up with this one:

https://www.yacco.com/product/300-avx-1000-2t/

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Each engine may have its own personality. Some may feel more compression than the next guy. Oil burping happens with 4 turns vs 15 turns. Some gearboxes squeak on shutdown and others don't. Some may get vapor lock easier than another.ect....

 

Don't get worried if yours is a bit different than the other guy's.

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CT2K   

Roger Lee, many thanks for your reassuring words.

My gratitude goes to all those who contributed and shared their wisdom and experience, whether it is to this question of compression or to all other questions I have asked since I joined. I have to say that I always got my questions answered. I also benefited a lot from reading other available discussions.

Also, thanks to all those who cared and stopped to read.

 

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Anticept   

If you want to make it easier to burp, let the air get by the rings at TDC, then quickly rotate to the next TDC. I can burp one within 2 prop rotations usually.

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