Oil Seeping between case halves

Don't fix what is not broken :)

I would not worry about that yet. There are no gasket between the pump and the housing I believe, just some loctite compound. The oil could be coming because lack of sealing compound, but also due to small cracks in the aluminium casing. Opening will just make it worse. 

I believe you can fly another 600 hours without any worries, just inspect it.

Also, the amount of oil that has left the engine thru the leakage is very small. If it would be so much so you need to top up, it would be a real mess everywhere. I believe your engine is using oil internally due to too much carbon on the lower piston ring. Nothing to worry about too.

Oil leaks are tough to find as the oil runs everywhere in flight. Most likely from one of the many o-rings that seal the motor.

hello Bruce

So let's consider this and be careful.  First there is no oil bath, only crankcase pressure that drives the oil back to the oil sump.  I doubt that the actual leakage is any type of crack or damage to the aluminium.  It may be possible that the Loctite sealant is allowing some weeping but also unlikely.  Secondly consider that Rotax will not give out the splitting process to the case, that is reserved for only approved overhaul facilities and considered too complex for people without the correct tooling and approvals.  That might be an option if you ship it to a shop listed with approvals for that type of work.  The 2009 vintage crankcase has a complex angle torquing procedure and the case bolts are stretch bolts.  Those bolts would all have to be replaced once removed so a full bolt kit would need to be installed.  Additionally there was an upgrade to the bolts so a small machining process at the overhaul shop is needed to mill off 3mm on one of the bolt bosses just behind the oil pump on the number 2 cylinder side...sounds complicated and it can be so best done by an approved facility.  

Food for thought.  There is a process shown in the installation manual to check the crankcase pressure when you are verifying your installation.  the crankcase pressure is a critical check to be sure that we do not have too much back pressure within the case.  Perhaps consider this as a way to see if there is not excessive pressure that might drive oil out of any proosity or even O-ring on the engine.  

You said some weeping is from the oil pump housing.  This area is sealed with 3 O-rings.  i would remove the pump and replace them with new and at the same time be  sure to put Loctite 5910 (Loctite 598 is the automotive equivalent and easier to find in the USA) on the small part line for the case halves.  Just a small dab on the parting line on the 12 and 6 clock position of the parting line is sufficient.  this helps seal in any oil weeping that is coming from that area around the cam end were it drives the oil pump.  If you find that cavity under the cam filled with oil that is most likely where the weeping is coming from.  Oil can travel a long way and follow the entire crankcase parting line on the lower side so do this first before you commit to an expensive case splitting.  

Let us know how it works out.

Cheers

Thanks for all of that info. I knew I didn't want to split the case. So that was out of consideration. I will replace the O rings in the Oil Pump housing and see if that helps. In fact as you mentioned that may be the only place it is weeping and it is spreading from there.

Thanks again