Primarily for general aviation discussion, but other aviation topics are also welcome.
#1704387
Given the oil system and procedure for checking oil level there is a practice of turning the engine over ignition off prior to start in order circulate oil to avoid starting with 'no' oil in the system.

I'd be interested to hear views from those with some knowledge of the systems.

Do you not turn it over and just start?
Do you turn it over until there is pressure?
Do you turn it over a few times to begin the flow?
Other?

TIA
#1704400
Okay, let me start again….must be the wine. :oops: :shock:

As you'll know the Rotax does not have a sump for the crankshaft to pick up oil and throw it around. The burping scavenges the 'oil system' of oil by pulling it back to the external sump/tank. To compound that the act of turning the engine over to burp also removes oil from all internal surfaces. :(

Having done all that a common practice, at least in my neck of the woods, is, when starting, to turn the engine over on the starter, ignition off. The idea is that turning the engine over draws oil from the external sump/tank to the engine prior to the loads being imposed when running.

I thought the practice widespread, I'm getting the impression from responses that it is maybe not so. :D
#1704404
1.Pull the Prop through by hand untill it Burps.
2. Check the oil on the dipstick in the oil tank.
3. Start the engine....Oil Pressure will come up immediately.
Thats all there is to it!
Never fear, oil is not removed from all surfaces!
The oil filter is still full of oil also the oil cooler will still have oil in it.
Oil pressure will come up immediately!
Last edited by Shoestring Flyer on Sat Jul 06, 2019 9:51 pm, edited 2 times in total.
#1704405
Miscellaneous wrote:Okay, let me start again….must be the wine. :oops: :shock:

As you'll know the Rotax does not have a sump for the crankshaft to pick up oil and throw it around. The burping scavenges the 'oil system' of oil by pulling it back to the external sump/tank. To compound that the act of turning the engine over to burp also removes oil from all internal surfaces. :(

Having done all that a common practice, at least in my neck of the woods, is, when starting, to turn the engine over on the starter, ignition off. The idea is that turning the engine over draws oil from the external sump/tank to the engine prior to the loads being imposed when running.

I thought the practice widespread, I'm getting the impression from responses that it is maybe not so. :D


“Burping” the engine is done slowly and as you pull over each cylinder the pressure in the sump pushes the oil back in the tank. The oil pump is not turning quick enough to move any oil out of the galleries or surfaces.

Some people turn the engine over on the starter and then switch the mags on to lesson “kickback” especially with heavy VP prop and/or not having the soft start module fitted, mainly on the “S” version.
T67M liked this
#1704416
You would probably find it useful to source a Rotax912 Operators manual, either hard copy or if you Google it they can be found in lots of places on-line.
Also worth subscribing to if you have a Rotax engined aircraft is https://www.rotax-owner.com/en/ ..... Lots of advice, videos and useful tips for any Rotax owner. Some parts of Rotax- owner. com you can access without subscribing.
#1704429
Cheers @Shoestring Flyer , I have all the manuals I could desire and am familiar with them. It's the standard; oil pressure should come up within 10 secs.

Without going in to the pros and cons of what the manual says I was asking what in practice happens in the field. After all it's not unusual for the manual's instruction to be tweaked in the field. :wink:

It seems the standard is to jump in and start up. :D
#1704455
ArthurG wrote:...turn over without spark on, check oil pressure comes up, then mags on and start...

Ah ha, someone who does as I describe. :D

Thanks Arthur. The purpose of my question was to establish how wide spread the practice is. So far it seems not very.
#1704459
Miscellaneous wrote:It seems the standard is to jump in and start up. :D



Not where I'm based it's not , Misc.

I fly behind a far superior engine [ :D ] but all the Rotax 9-series users where I'm based do exactly what Shoestring suggested.

If your engine has stood for some time , it may take slightly longer to 'gulp' than when in regular use , which is why it's a good idea to pull the prop. through a few blades whilst you listen .

It's called 'good practice' old boy . :D