Coolant in the oil tank?
Hello Rotax forum members,
Since this is the first time I post something here (long time reader) I will introduce myself: I recently finished an Europa XS Monowheel and I have a 912ULS engine in it. The engine I have was purchased "rebuilt" from a Rotax authorized heavy maintenance facility. Not overhauled. The entire engine/gear box was disassembled, inspected, what needed to be new was replaced and in general looks like a good job. I did have a few issues with the accessories but all was easily fixed. The engine is SN 5,65X,XXX vintage (I think it was born around 2008). The engine now has 85 hours and has run well (we estimate 2000 hrs when it was pulled out of a CTLS and rebuilt)
I decided to change the oil today even if not at 100 hrs (oil was replaced also at 25 hrs). When I removed the oil tank plug I found that the first thing to come out briefly was an orange liquid. It wasn't much (tablespoon maybe, hard to tell) but it's clearly some sort of contamination. I can see a few droplets of the orange stuff in my funnel walls. Since my coolant is orange I assume it is coolant. It doesn't mix with the oil. The oil is quite dark but doesn't seem to have any water in suspension as it is pretty clear.
Since not much contamination was found I am going to replace the oil/filter and fly a few hours and inspect again. I did open the oil tank to clean and it was fairly quite clean once I wiped the oil off the wall. Couldn't see anything that looked like coolant inside despite some oil accumulated on the bottom screen tray. I'm also going to drain the fuel and replace with something else.
A few facts: My engine runs somewhat cool. Oil temp is around 180 when cruising (5000 RPM) in Florida summer and rarely goes up much more than that except during climb. I just came from a trip from SC to FL with the engine running good but oil temps were low (150 ish). During the trip I stopped for fuel at an airport with 93 Mogas. Not sure about the quality of that fuel and I have some doubts. The fuel was a bit yellowish but clear.
So my question is: Can coolant really get into the oil circuit? if so how? I was told this is very strange. Are there any seals in the head that will allow coolant to migrate to the oil?
The fuel pump does show a few drops on the drain hole but it nothing on the engine compartment looks dirty as if the pump leaked badly. I was told these drops are normal. I assume that since the water pump has an oil and water seal separated by a space with air it would be unlikely to see coolant get into the oil through here.
The coolant has gone down (expansion tank) since I first flew the airplane back in March but I just returned from a 7 hour trip and the level at the reservoir has not changed.
Is it possible for the coolant to make it to the oil?
Chris
