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"Burping" the oil in a 912

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Dennis.Kirby(at)kirtland.
Guest

Posted: Tue Jun 30, 2009 9:12 am Post subject: "Burping" the oil in a 912

Classification:  UNCLASSIFIED  

 

  

Here’s a question for our Kolb Friends flying the 912 –  

   

When checking the oil level during preflight, how many times must we turn the engine over in order to get an accurate oil level reading?  

   

The common wisdom regarding checking the oil (including instructions in the Rotax Maintenance Manual) tell of the need to “burp” the engine, which we do by turning the prop for several revolutions prior to checking the oil level.  Doing this transfers oil from the engine case back into the oil tank, thus giving an accurate oil level indication on the dip stick.  

   

Well, I did this yesterday when I went to fly my Mark-3, but managed to 1) NOT get an accurate oil level reading, resulting in 2) splattering of overflow oil all over my prop and tail after the flight!  

   

It seems that, as the 912 engine sits idle, oil slowly drains from the oil tank into the engine case.  The longer it sits, the more oil that drains out.  It had been six weeks since the last time I flew (fortunately, that is not common!), so I suspect THAT is the reason the oil level indicated so low at first.  I rotated the prop at least twenty revolutions, thinking it was enough.  I then checked the oil to find that it was still reading a bit low.  So I added half a quart.  

   

After flying, my tail was soaked with sprayed-out overflow oil.  (what a mess!)  I checked my oil level, and found that it was now way too high.  Obviously, I did not get all the oil from the engine to the tank on preflight, and I got an erroneous “low oil level” reading on the dip stick.  

   

So back to my question: how many revolutions must the 912 be turned?  Apparently, 20 is not enough!  

   

Dennis Kirby  

Cleanin’ up my Kolb with rags and 409 in  

Cedar Crest, NM  

      

Classification:  UNCLASSIFIED   

 

  [quote][b]

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Tue Jun 30, 2009 9:25 am Post subject: "Burping" the oil in a 912

Did you stop when it burped?  Or did you simply stop at 20?

On Tue, Jun 30, 2009 at 11:59 AM, Kirby, Dennis CTR USAF AFMC MDA/AL <Dennis.Kirby(at)kirtland.af.mil (Dennis.Kirby(at)kirtland.af.mil)> wrote:

 [quote]               

Classification:  UNCLASSIFIED  

 

Here’s a question for our Kolb Friends flying the 912 –  

  

When checking the oil level during preflight, how many times must we turn the engine over in order to get an accurate oil level reading?  

  

The common wisdom regarding checking the oil (including instructions in the Rotax Maintenance Manual) tell of the need to “burp” the engine, which we do by turning the prop for several revolutions prior to checking the oil level.  Doing this transfers oil from the engine case back into the oil tank, thus giving an accurate oil level indication on the dip stick.  

  

Well, I did this yesterday when I went to fly my Mark-3, but managed to 1) NOT get an accurate oil level reading, resulting in 2) splattering of overflow oil all over my prop and tail after the flight!  

   

It seems that, as the 912 engine sits idle, oil slowly drains from the oil tank into the engine case.  The longer it sits, the more oil that drains out.  It had been six weeks since the last time I flew (fortunately, that is not common!), so I suspect THAT is the reason the oil level indicated so low at first.  I rotated the prop at least twenty revolutions, thinking it was enough.  I then checked the oil to find that it was still reading a bit low.  So I added half a quart.  

   

After flying, my tail was soaked with sprayed-out overflow oil.  (what a mess!)  I checked my oil level, and found that it was now way too high.  Obviously, I did not get all the oil from the engine to the tank on preflight, and I got an erroneous “low oil level” reading on the dip stick.  

   

So back to my question: how many revolutions must the 912 be turned?  Apparently, 20 is not enough!  

   

Dennis Kirby  

Cleanin’ up my Kolb with rags and 409 in  

Cedar Crest, NM  

      

Classification:  UNCLASSIFIED   

 

   	  Quote: 	
		  



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[b]

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

tlongo

Joined: 17 Jul 2007
Posts: 14

Posted: Tue Jun 30, 2009 9:47 am Post subject: Re:

Check it after each flight, and if it has been a while and you don't remember start it and let it run for a couple of minuets then check it.

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Tue Jun 30, 2009 9:51 am Post subject: Re:

[quote="Dennis.Kirby(at)kirtland."]Classification:  UNCLASSIFIED  

 

  

Hereâ€™s a question for our Kolb Friends flying the 912 â€“  

   

When checking the oil level during preflight, how many times must we turn the engine over in order to get an accurate oil level reading?  

   

The common wisdom regarding checking the oil (including instructions in the Rotax Maintenance Manual) tell of the need to â€œburpâ€ the engine, which we do by turning the prop for several revolutions prior to checking the oil level.  Doing this transfers oil from the engine case back into the oil tank, thus giving an accurate oil level indication on the dip stick.  

   

Well, I did this yesterday when I went to fly my Mark-3, but managed to 1) NOT get an accurate oil level reading, resulting in 2) splattering of overflow oil all over my prop and tail after the flight!  

   

It seems that, as the 912 engine sits idle, oil slowly drains from the oil tank into the engine case.  The longer it sits, the more oil that drains out.  It had been six weeks since the last time I flew (fortunately, that is not common!), so I suspect THAT is the reason the oil level indicated so low at first.  I rotated the prop at least twenty revolutions, thinking it was enough.  I then checked the oil to find that it was still reading a bit low.  So I added half a quart.  

   

After flying, my tail was soaked with sprayed-out overflow oil.  (what a mess!)  I checked my oil level, and found that it was now way too high.  Obviously, I did not get all the oil from the engine to the tank on preflight, and I got an erroneous â€œlow oil levelâ€ reading on the dip stick.  

   

So back to my question: how many revolutions must the 912 be turned?  Apparently, 20 is not enough!  

   

Dennis Kirby  

Cleaninâ€™ up my Kolb with rags and 409 in  

Cedar Crest, NM  

      

Classification:  UNCLASSIFIED   

 

   	  Quote: 	
		  [b] 	




Hey Dennis,



A trick for this I initially learnt from Ronnie Smith (and subsequently found is suggested in the oil check video on rotax-owner.com) is to turn the prop over slowly instead of popping it through. This allows lots more blowby past the rings as you go through the compression strokes really slow. That pushes the oil out to the tank a lot faster. 



This way I get the gurgle in I'd say about 10 blades, somewhere in there where it used to sometimes take enough turns to make my arms tired....



LS

_________________
LS
Titan II SS

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Jun 30, 2009 9:58 am Post subject: "Burping" the oil in a 912

Dennis:

  

 Check your oil level on post flight.  The  engine is warm/hot and the oil is pushed out of the crankcase during  operation.

  

 If you want to do it during preflight, crank the  engine, let it run a couple minutes, shut down and check.

  

 912's have a great history of not requiring oil to  be added between changes.

  

 I usually end up adding a little too much during  oil change.  This ends up on prop and tail section during  flight.

  

 They will also blow oil when you get into a severe  down draft as oil is forced up to the top of the tank where crankcase pressure  forces it out the breather tube.

  

 A lot of oil will drain back into the crankcase if  the antisiphon valve is not the best.  Over the years, I have found  Rotax as well as Fram oil filters that would leak down. The longer they sit  idle, the more oil is going to drain back.

  

 john h

 mkIII

 [quote]    When checking the oil level during    preflight, how many times must we turn the engine over in order to get an    accurate oil level reading?

      

    

    

    

Dennis Kirby   

 

[b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

slyck(at)frontiernet.net
Guest

Posted: Tue Jun 30, 2009 11:08 am Post subject: "Burping" the oil in a 912

Why don't they locate the oil tank below the engine?



My suzuki tank is 2 feet below.  Gravity does a great job.

BB



On 30, Jun 2009, at 12:59 PM, Kirby, Dennis CTR USAF AFMC MDA/AL wrote:

 	  Quote: 	
		  Classification: UNCLASSIFIED



Here’s a question for our Kolb Friends flying the 912 – 

When checking the oil level during preflight, how many times must we turn the engine over in order to get an accurate oil level reading?

 

The common wisdom regarding checking the oil (including instructions in the Rotax Maintenance Manual) tell of the need to “burp” the engine, which we do by turning the prop for several revolutions prior to checking the oil level.  Doing this transfers oil from the engine case back into the oil tank, thus giving an accurate oil level indication on the dip stick.

 

Well, I did this yesterday when I went to fly my Mark-3, but managed to 1) NOT get an accurate oil level reading, resulting in 2) splattering of overflow oil all over my prop and tail after the flight!

 

It seems that, as the 912 engine sits idle, oil slowly drains from the oil tank into the engine case.  The longer it sits, the more oil that drains out.  It had been six weeks since the last time I flew (fortunately, that is not common!), so I suspect THAT is the reason the oil level indicated so low at first.  I rotated the prop at least twenty revolutions, thinking it was enough.  I then checked the oil to find that it was still reading a bit low.  So I added half a quart.

 

After flying, my tail was soaked with sprayed-out overflow oil.  (what a mess!)  I checked my oil level, and found that it was now way too high.  Obviously, I did not get all the oil from the engine to the tank on preflight, and I got an erroneous “low oil level” reading on the dip stick.

 

So back to my question: how many revolutions must the 912 be turned?  Apparently, 20 is not enough!

 

Dennis Kirby

Cleanin’ up my Kolb with rags and 409 in

Cedar Crest, NM

Classification: UNCLASSIFIED



 	  Quote: 	
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 [quote][b]

by0ung(at)brigham.net
Guest

Posted: Tue Jun 30, 2009 11:40 am Post subject: "Burping" the oil in a 912

Here’s a question for our Kolb Friends flying the 912 –  

   

When checking the oil level during preflight, how many times must we turn the engine over in order to get an accurate oil level reading?  

   

   

Dennis Kirby  

   

 	  Quote: 	
		  >>>>>>>>>>>>>>>>>>>>>.  

   
	


Dennis  

   

Remove the oil cap,  then rotate the prop until you can hear the blow by gasses start to sputter,   before the sputter it will be pushing back only oil..   when the sputter starts it will be a mix of oil and air.  

   

Cant tell you how many turns…   just till you hear it..  

   

Boyd  

   

       [quote][b]

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Wed Jul 01, 2009 3:08 am Post subject: Re: burping a 912

RE:

.....Hereâ€™s a question for our Kolb Friends flying the 912 â€“ 



When checking the oil level during preflight, how many times must we turn the engine over in order to get an accurate oil level reading? ....

To add a bit to what Lucien said, I've found that holding the prop against the high resistance part of the prop turning process, until the resistance bleeds down, speeds up the burping process and reduces the number of blade turns required to hear the burp. 



How many turns it takes depends upon how high the tank is relative to the case and how long it has been sitting.  I don't check the oil until I hear the burp, and have never had a too-much-oil mess.



I can't answer BB's question about why the thank is mounted where it is, but Rotax is very specific about the acceptable height range.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jul 01, 2009 3:52 am Post subject: "Burping" the oil in a 912

> When checking the oil level during preflight, how many times must we turn 

the engine over in order to get an accurate oil level reading? ....

Dennis K:



I went over to the airstrip yesterday to see if I still had an airplane.



Decided to check the oil and see if it would crank.  It has been sitting 

since I landed, the end of May.



Took 21 blades, or 7 complete revolutions of the prop, or 17 crank revs to 

get it to burp.  Probably a good idea to do the burp maneuver.  Should help 

prelube the engine before start up.



The 912ULS fired right up and ran well.



Last winter I put a small 2 amp solar panel on my hanger.  Keep it plugged 

into the mkIII battery.  Battery stays hot now during extended periods of 

storage.  Before the solar panel, the battery would pull down from operation 

of the aircraft clock, which is wired direct to the battery.  Nice not to 

have to jump start the airplane, plus it is much better for the life of the 

battery.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Ralph B

Joined: 14 Apr 2007
Posts: 367
Location: Mound Minnesota

Posted: Wed Jul 01, 2009 6:45 am Post subject: Re:

Dennis,



As John and others have said, check the oil level after your flight for an accurate reading on the dipstick. I would say it takes about 10 revs before hearing the "burp". Do this with the oil cap off. For some reason, anything over the lower level on the dipstick is siphoned out of the reservoir and ends up on the prop. On my Kolbra, I cannot get at the drain plug, so I have to siphon the oil out with a hand pump vacuum container. It works well, but leaves some oil in the reservoir. I remove the ring on the oil reservoir and stick a tube down there.



While on the topic, the oil of choice is Honda HP4 semi-synthetic motorcycle oil (without moly). This is what I use in my Goldwing too. It's good for the gears in the 912 as well as the engine.



Ralph B

_________________
Ralph B

Kolb Kolbra 912uls
N20386
550 hours

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