Clean oil tank / Purge
Oh! Sorry! Rotax 4-Stroke...? Okay :lol:
Keeping to Rotax,
I'm wondering about practices regarding cleaning out the oil tank and then possibly purging the oil lines,
In the maint man, fig 23 shows the oil system, fig 27 the oil tank, sec 11.6 for cleaning, 11.7 purge.
I ask people, and I hear if you clean the tank, you must purge. Then I ask more, and I learn it's if you aerate much of the suction side that requires the purge.
11.7 says purge if the "lubrication system was opened and voided." In an oil change, which does not require a purging (also see RO video on oil change), the oil tank is opened (cap) and voided (drained), and filter changed..., leaving me to think that THAT is not the opening and voiding they're concerned about.
I've been operating on belief that a significant amount of air in the suction side would make the oil system lose prime.
Yet, when, during an oil change, the tank is opened cap off and fully drained, the oil in the suction side tube that sticks down into the tank will drain/clear, somewhat, via dripping, which introduces air into that suction side of the system---just not enough to require purging. Then, when the tank is refilled, the oil would NOT refill that part of the suction line, because of the air in the line above it, leaving air in the line after the oil change.
Soooooo.......
How would that be different from disconnecting the top of the drained oil tank, lowering the tank below the tubes above, cleaning it out (say after using 100LL), then raising tank again/securing it, refilling?
So far, it seems functionally the same as an oil change, per allowing air into the downward part of the suction line.
I see the importance of a purge if a lot of air were introduced there, but I don't see how a tank cleaning, like this, would require it, any more than an oil change, which does not.
I would be pleased for some of you to correct my flawed thinking.
Thank you