Primarily for general aviation discussion, but other aviation topics are also welcome.
#1704460
@Chris Martyr , since my question did not relate to the burping my 'jump in and start' comment referred to actions after properly checking oil level. :thumleft:

I turn over a few seconds ignitions off then stop, switch on ignitions and start, one other at my field does this, three others do not and simply turn over with ignitions on from the onset.

Thanks @Nomad63 , exactly the info I was curious about.
#1704471
I look at the dipstick first. I have an elderly Kitfox with the tank mounted very high - bad design, against Rotax rules - and if stood for a while the oil syphons down into the engine. If the oil has gone below the dipstick then the suction pipe may be exposed and doing the gurgling could suck air. In that case after gurgling and then checking the dipstick I do the check for a bit of pressure exercise.
If the oil is still on the dipstick I just gurgle, check the dipstick again, and start.
If your tank is mounted at a height as per Rotax instructions the syphon down to a dangerous level risk should not exist.
AIUI the turn it and check for pressure is part of purging - when it is known that there could be air in the system - not of routine gurgling. It's only necessaryif the engine has been turned without oil covering the suction pipe. It's not even necessary after an oil and filter change provided the engine has not been turned while doing it.
Last edited by MikeW on Sun Jul 07, 2019 8:45 am, edited 1 time in total.
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#1704472
Thanks for your explanation @MikeW . :thumleft:

At the risk of further confusion there is also a school of thought that burping is only strictly necessary if in fact the oil level is proved to be low on first pre burp checking. IE if the oil level is showing, say, half way between min and max then there is clearly sufficient oil in the system and burping is therefore not necessary.
#1704473
Miscellaneous wrote:Thanks for your explanation @MikeW . :thumleft:

At the risk of further confusion there is also a school of thought that burping is only strictly necessary if in fact the oil level is proved to be low on first pre burp checking. IE if the oil level is showing, say, half way between min and max then there is clearly sufficient oil in the system and burping is therefore not necessary.


I agree with that but didn't want to further complicate my reply (and I don't actually do it).
I believe if you can find a very old OM it does say start up, run briefly, shut down and then check oil level. Gurgling was introduced later when the syphoning danger was realised.
Last edited by MikeW on Sun Jul 07, 2019 8:46 am, edited 1 time in total.
#1704476
Here's another complication for you.
Strictly speaking, if the system has got into a state where it could have sucked air and you have to purge by turning until you get a bit of pressure, this should be followed up by running for a few minutes and then removing all the rocker covers and checking for no play in all the 8 rockers i.e. checking there is no air in the hydraulic cam followers.
No I do not do that routinely!
#1704479
It’s a very simple procedure that Rotax requires you to do, so why not ? The additional benefit is you get to feel compressions on all cylinders so could give you early warnings of valve/ piston problems,
Removing the oil from the Engine back to the oil tank before starting reducers drag of the crank through the oil, That’s why it’s called a dry sump, Certainly in winter it would reduce the starter motor load and knock on effect of battery voltage and making the Carp Ducati regulator work overtime,
#1704503
Isn't it amazing, the pampering we have to give these expensive supposedly high quality toys compared with what we expect of our relatively cheap car engines! Turn and go - and how often do they let you down?
Not to mention the price:sophistication balance.
Where else would you find an expensive new engine using Bing carbs? The motor cycle industry virtually abandoned them not that long after the 912 came out with them on.
#1704515
Burping tells you when all the oil has been pushed into the tank. At this point you will be able to dip it and obtain an accurate indication of how much you have. I generally only pull the prop through until the dipstick shows the oil level to be within range. I rarely bother turning it all the way until it gurgles except after an oil change, when I want to know exactly what level we are starting with.

In my understanding, the procedure is there in order to be able to assess the oil level, not for any other purpose.
#1704523
Conrad Beale ( Skydrive/Conair/Ex Rotax UK Dealer))used to talk about Hydrostatic lock and the possibility of bending a conrod during winter months when the oil is particularly thick if you did not 'burp' a Rotax 912, so returning the oil to the tank before starting. He said he had seen it happen!
#1704527
MikeW wrote:Isn't it amazing, the pampering we have to give these expensive supposedly high quality toys compared with what we expect of our relatively cheap car engines! Turn and go - and how often do they let you down?
Not to mention the price:sophistication balance.
Where else would you find an expensive new engine using Bing carbs? The motor cycle industry virtually abandoned them not that long after the 912 came out with them on.


What finally got me to pay up and learn to fly was when I caught up with a friend in 2007 who had learned to fly and bought himself a Sky Ranger. He took the engine cover off and proudly showed me that it was fitted with the future of light aviation, the 912 fitted with Bing carburettors. Crikey, I thought, I haven't seen those since a BMW flat twin from the late 70s.

Anyway.

1. Buy a Jabiru.
2. Check oil. 1/4 up the dipstick is fine otherwise it just blows out any more.
3. Climb in, fuel on, master switch on, ignitions on, throttle closed.
4. Hold choke fully on 'Clear Prop', turn starter. Off she goes after a couple of blades.
5. Warm up for a couple of minutes.
6. Fly.

PS. It's got a Bing....................
seanxair liked this
#1704535
Let me first say I do burp a cold engine, however:
The thought of prop turning without chocks or someone at the controls does not sit well with me.
The intro of the 912 brings forth several issues when viewed from those who are more used to "most/all?" Other aeroengines.
PS I have seen overfilling of rotax oil due to lack of burping.
PPS I also like to compression check these other engines and leave the prop just off compression to ease starting loads. I imagine this could start another topic