Hi all,
I just wanted to give you an update on my Rotax leaking crankcase. About a
year ago I saw a small oil leak start on the engine just behind the gearbox
on the flat machined surface on top of the engine. After a while the
leaking area started to slowly progress along the case towards the back of
the engine and then along the bottom. While I was at the Oshkosh airshow I
went and talked to the mechanic from Kodiak to get his opinion. He told me
that some 912 / 914's were getting crankcase fretting and over time the
cases were damaged to such an extend that they had to be replaced. His
advice to to have the engine stripped and inspected.
Well this winter I removed the engine and took it to Leading Edge Airfoil
who has a rotax trained A&P on staff. He stripped the engine and sure
enough it was showing signs of fretting. The engine has about 750 hours on
it at the moment. Fortunately it was not too bad and he was able to dress
the cases and re assemble the engine. He used a different sealant, 5150 I
believe it was called instead of the red Locktite sealant that was on
before. He tells me that Rotax now specify this sealant. It is a heavier
material and apparently is swells a little after application, perhaps from
heat, I am not sure. He felt confident that this would tighten things up
and I should not have any problems. A couple of other things to note, at
750 hours there was no sign of wear in any part of the engine. The only
thing he mentioned was a slight scuff on a cam follower that would have been
---From not priming the engine properly after an oil change. I remember
exactly when I did that ! He as able to polish it out. There was a little
bit of oil flashing on some of the piston skirts and he told me that this
was from using either mineral or semi synthetic. I have been using the
recommended Penzol motorcycle oil although this has dropped off the list in
recent times, so I changed to the Valvoline Durablend. He was strongly
recommending I go to a full synthetic oil. He also wanted me to stop using
the Challenger oil filters, he tells me that they have less pleats in them.
The only other thing of note was the Turbo charger bracket was broken.
So it would appear that Kodiak was right and if I hadn't had this work done
I would have lost the cases. While he had it apart he overhauled the
gearbox which was due, replaced the plugs, and the rubber boots on the
carburettors, so my oil leak repair came to 3900 dollars. Ouch. Rotax
really have no shame, the gasket set is over a 1000 dollars for something
that has a trivial manufactured cost but there is little that any of us can
do about that matter.
The aircraft is going to be a little while before it is flying again, I have
decided to take a crack at some cooling modifications while it is all apart.
Paul
|