bgl

bgl

Member
I purge my Rotax engine oil before first flight of the day by turning the prop and getting a burp from the oil filler.The rest of the day or return flight home I just start the engine. Question If I check my oil when putting my plane away for the day and add if needed Do I have to purge the oil by turning the prop before starting or can I just start the engine. Maybe if I run the starter with the mag off to pump the oil through first then start the engine if I didn't flood it first.
 
bgl said:
I purge my Rotax engine oil before first flight of the day by turning the prop and getting a burp from the oil filler.The rest of the day or return flight home I just start the engine. Question If I check my oil when putting my plane away for the day and add if needed Do I have to purge the oil by turning the prop before starting or can I just start the engine. Maybe if I run the starter with the mag off to pump the oil through first then start the engine if I didn't flood it first.
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Pretty hard to flood a 912.

Turn it over with the starter, mags off, choke on, for 3-4 seconds, then mags on to start. Helps to reduces kick back potential in cold weather also.

It is very rare that you will need to add oil between changes. I check mine after flying.
 
Checking the oil level after you fly saves a whole lot of hand turning and burping the next time you fly - it's the easy way to check the oil level....

Bob Bogash
N737G
 
Yep, everything here makes sense. I still wind up the spring and check oil before every flight. I guess it's just OCD!
 
Just Curious

As a non-Rotax user, just what is it about the design of the Rotax that requires the "burping" technique?

And what happens if you don't "burp" the engine?
 
Pete - -

As the engine cools, it will take some oil back into the engine. Burping is the only way to know for sure how much oil is in the tank. It is much easier to burp AFTER flying. If you don't see oil on the floor next time, you don't have to check it then, or at least burp it. The level may not be the same as when you did it warm, but you get used to it.
 
Burping the Rotax

PCHunt said:
As a non-Rotax user, just what is it about the design of the Rotax that requires the "burping" technique?

And what happens if you don't "burp" the engine?
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The reason for so-called "burping" is to be able to get an accurate reading of the oil level by driving all of the oil that may be in the crankcase into the oil tank. A rather load burp occurs out of the tank. You then read the dipstick.

The Rotax, being the thoroubred that it is, has a dry sump oil system much like a Porsche. By turning the prop you are pressurizing the crankcase to move the oil all into the tank. On the Porsche we check the oil while the engine is idling, no propeller spinning to worry about.

You don't have to burp the Rotax and nothing will happen if you don't, provided you know there is adequate oil by some other method, like checking it after flying. Of course if you are not the only pilot, you would want to burp and check before you fly.

I don't rue the time spent burping the motor, it's all part of the fun for me. And I feel it can't hurt to move oil into all the bearings and lifters before you hit the starter. It kinda like petting yer horse before climbing aboard.

Tony
 
Most dry sump engines have a scavenger pump that returns the oil to the tank.
The Rotax depends on crankcase compression.
 
Tony_T said:
You don't have to burp the Rotax and nothing will happen if you don't, provided you know there is adequate oil by some other method, like checking it after flying. Of course if you are not the only pilot, you would want to burp and check before you fly.
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No need to burp the baby unless you want to - if the oil is above the minimum, you're good - burping will only return more oil back to the engine.

TODR
 
JBPILOT said:
Burping will not return more oil to the engine - tank yes.
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My bad. Posting before coffee = no no. Since I've had 2 cups today, I should be good to go :)

Our routine was to check the oil in the TANK. If it was good, no problem, go and fly. If not, burp the baby and have the oil return from the ENGINE to the TANK. If good, go and fly. If not, add and note on aircraft logbook (not the official one, just one we keep in the plane), and go fly.

If you keep the tank too full, which is in the top half of the stick range without burping, the engine will happily correct the situation by venting some out the vent line.

TODR
 
Burping with the starter

Just a note on using the starter with ignition OFF to burp the engine - ONLY do this if you intend to start the engine immediately after checking the oil. Cranking the engine over without firing WILL draw mixture into the cylinders (on a carburetted engine). If the engine is not started to burn this off, it will condense on the cylinder walls and tend to wash off any lubricant. If this is done too many times it will lead to rapid bore wear. :eek:

However - if the engine has not been run for a while, this technique can be used to get oil flowing (and oil pressure) before you pull the choke out and turn the ignition on. This helps ensure you have oil pressure immediately when the engine fires! :)
 
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