Oil check procedure shows sometimes low

by Przemysław Wiśniewski in 912 / 914 Technical Questions 9 years ago

Hi. I'm trying to track problem with oil level.
A few times I found by morning, that oil level is below minimum or minimum. After I added 0,5l I found that oil is thrown by ventilation...

I found, that sometimes my engine shows to low level but next day everything is ok without adding...

I found also, that If I'll "gurgle"/check hot oil after flight and then check it next day I have good level. If after flight I leave plane just and next day "gurgle" oil by morning sometimes it shows low..
Probably there is any problem with transfering cold oil back to tank. When I'll make it on hot and then check next day on cold everything is ok.
Oil tank is located like in my other plane, plane is C42 and engine 912ULS.

I'm using aeroshell rotax oil and making good check procedure, in other planes I have no problems.
Tubes are standard rotax, not bended..

What can be reason of this magic?

Re: Oil check procedure shows sometimes low

by Roger Lee » 9 years ago

Roger Lee

127 5.2k 4.78k

The oil level check isn't exact. It can vary some. Don't get too worried about minor fluctuations. Many think they are using oil between changes and in fact it is just a minor accuracy irregularity. If you are having a real oil reduction issue you'll see evidence on the bottom of the plane, all over the engine or in the exhaust pipe. The oil level check can vary between hot and cold checks and even on different days.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Oil check procedure shows sometimes low

by Wes Huff » 9 years ago

Wes Huff

1 3 0

I've wanted to ask this question for a while and this seems like the right tread. What do you think it means (if anything) that my 912ULS burps on the first compression stroke. Not the first complete rotation of the prop. The first compression.
My previous 912 took several rotations of the prop. Just wondering.

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Re: Oil check procedure shows sometimes low

by Roger Lee » 9 years ago

Roger Lee

127 5.2k 4.78k

The check can be different between different aircraft and engine setups. Some gurgle with1-2 rotations and some take a lot of rotations. It all depends on how much oil is in the bottom of the case to move back to the bottom of the tank. It can vary aircraft to aircaft and sometimes day to day on the same plane.
I wouldn't worry too much of some small differences.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Oil check procedure shows sometimes low

by Przemysław Wiśniewski » 9 years ago

Przemysław Wiśniewski

65 247 3

But I have big differences. Sometimes it show's below minimum leve. Than I should add oil but now I know, that later I will have too much. It's hard to say also if engine burn's oil and how much.
In other planes i have minor differences but never from half to under-minimum.

It can be with oil tank? Maybe dirty mesch or sth else?.

I must to be carry about oil consumption because I have small leakage from cylinder stund (previous thread) and I have to monitor it but if one day I have minimum and after add 100ml next day I have neat maximum then something is wrong..
I haven't smoke from pipe, compressions are ok so no reason to think that engine burn's oil.

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Re: Oil check procedure shows sometimes low

by Roger Lee » 9 years ago

Roger Lee

127 5.2k 4.78k

"But I have big differences. Sometimes it show's below minimum level. Than I should add oil but now I know, that later I will have too much. It's hard to say also if engine burns oil and how much."

I have seen this on quite a few engines and don't worry if I know the oil level is variable on that engine and I know there are no leaks or engine oil usage signs. Just adding oil because you think it is low has caused quite a few to overfill.

I think too many people overly worry about slight changes in oil level checks. The level can vary from day to day and engine to engine.

Since you know you have that leaking stud then keeping a close eye on the oil level is advisable and a low oil level could be a true indication.

If you are truly using oil it has to go someplace. It doesn't evaporate so it has to show signs of leaving the engine some place. It has to be a leak around the engine somewhere which shows up many times on the underside of the plane if it is a good leak. If it is only a drop or two from a valve cover then that may not leave the engine compartment and may be so slight as to not really affect the oil level. If you are burning oil that should show up on plugs and in the exhaust pipe and you should have oil level checks that get lower and lower on the stick. Normal oil level checks can vary some on the dipstick. I'm pretty sure you said somewhere you use AeroShell Sport Plus 4. That is 3 liters and all three liters should be used for an oil change. Some here in the US don't use AeroShell and use a US brand oil measured in quarts. That is 8 ounces less than Aeroshell. 3 liters during an oil change usually puts you close or at the top of the flat area on the dipstick.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Oil check procedure shows sometimes low

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