Rotating Rotax backwards

RalphInCA

RalphInCA

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RalphInCA
I was told never to rotate a Rotax engine (like in a light sport) backwards.

Why is this not permitted, and how much backwards rotation can you do before you will damage whatever it is you will damage?
 
I believe it can pull air into the oil system which would then need to be purged buy a special procedure. That said a little bit backwards doesn't hurt - like to find top dead center - that sort of thing.
 
Which Rotax?
Assuming 912/ 914, it pulls air into the lifters which can collapse which can result in damage. As noted, a little bit is usually OK.

You can find all of the documentation on line.
 
Capt. Geoffrey Thorpe said:
Which Rotax?
Assuming 912/ 914, it pulls air into the lifters which can collapse which can result in damage. As noted, a little bit is usually OK.

You can find all of the documentation on line.
Click to expand...

I agree the Rotax 912/914 series sshould not be turned backwards, but I don't know how introducing a little air into the tappets would cause damage. The valves are non interference with the pistons.

The purge system Rotax calls out is way over kill due to the varied installations. The height of the remote oil tank seems to be the concern. On a new engine install I would pull the plugs and use the starter to determine if the engine was making oil pressure. Never had a problem. :dunno:
 
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You have to turn the prop in the right direction about twenty times to get the motor to burp the air out of the oil system.
 
Geico266 said:
I agree the Rotax 912/914 series sshould not be turned backwards, but I don't know how introducing a little air into the tappets would cause damage. The valves are non interference with the pistons.

The purge system Rotax calls out is way over kill due to the varied installations. The height of the remote oil tank seems to be the concern. On a new engine install I would pull the plugs and use the starter to determine if the engine was making oil pressure. Never had a problem. :dunno:
Click to expand...
Rotax claims that there have been instances of engine damage. I don't recall exactly which of the hundreds of documents they publish makes that statement.
 
RalphInCA said:
Good stuff, thanks. In that writeup I did notice this:

"CAUTION: Do not turn the engine if any part of the oil system is open."

I have been opening up the oil filler cap, and then burping the engine. I guess I should leave the oil filler cap closed?


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Click to expand...

How would you hear the burp?
 
RalphInCA said:
Good stuff, thanks. In that writeup I did notice this:

"CAUTION: Do not turn the engine if any part of the oil system is open."

I have been opening up the oil filler cap, and then burping the engine. I guess I should leave the oil filler cap closed?


Sent from my iPhone using Tapatalk
Click to expand...
No - you are OK - you just don't want to turn it with the filter off, or an oil line disconnected. Having the cap open won't get air into the oil lines.

FWIW - the only time I burp is if the oil looks low enough that I think I might need to add.
 
The cap doesn't count as part of the oil system. It's really not a big deal. If you just need to turn the prop back a bit to align the bottom blade straight down, no worries. You just don't want to go more than a blade or so back. If you do get air in a lifter, it will self bleed, just don't try to make power clearing it, just let it click along at idle, it will go away. If it doesn't then usually you have to pull a rocker cover and stake the valve to collapse the lifter and clear the air bubble with the engine running.
 
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Henning said:
The cap doesn't count as part of the oil system. It's really not a big deal. If you just need to turn the prop back a bit to align the bottom blade straight down, no worries. You just don't want to go more than a blade or so back. If you do get air in a lifter, it will self bleed, just don't try to make power clearing it, just let it click along at idle, it will go away. If it doesn't then usually you have to pull a rocker cover and stake the valve to collapse the lifter and clear the air bubble with the engine running.
Click to expand...
ummm. The 912/914 relies on crankpressure from blowby to move the oil from the crankcase to the tank. Running with the rocker cover off will cause the oil to stay in the crankcase as the tank goes dry. I don't know the flow rate for the pump, but you have less than 3 quarts to play with.
 
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