Sport Pilot Talk

In the last few days I started noticing quite a bit of water on my oil tank cap.

Is this a symptom of a blocked oil breather tube ( I checked it visually but I should probably disconnect it and blow it with some air ) or should I look for some other culprit ?

This is just after 15 minutes engine ground run ...

Normal condensation I get when night temps are low, especially if humdiity has been high. Water collected in the oil boils off to steam above 212°F, and it has to go somewhere. Better your oil tank and cap than in your engine creating corrosion. Just wipe the water off the cap when you see it.

MrMorden wrote:Normal condensation I get when night temps are low, especially if humdiity has been high. Water collected in the oil boils off to steam above 212°F, and it has to go somewhere. Better your oil tank and cap than in your engine creating corrosion. Just wipe the water off the cap when you see it.

May I ask? Does anyone flying a Rotax ever see temps above 212F consistently? It’s got to be near 100 on the ground, as Inrecall. Remember, I’m a short timer flying the Rotax. On my last several flights, with temps 60-75F, oils 148-180F

In my case I have been chasing some engine gremlins recently ( carbs synch etc ) and have been doing lot of ground runups for the last 2 weeks so most likely the condensation comes from the fact that I never got to warm up the engine to reach 200 F ( or at least this was the explanation I was given at the Rotax Owners forum and it makes sense )

As far the temps - I do use the aluminium strips approach during winter and in the summer I have no problem reaching 212 F

Sling 2 Pilot wrote: May I ask? Does anyone flying a Rotax ever see temps above 212F consistently? It’s got to be near 100 on the ground, as Inrecall. Remember, I’m a short timer flying the Rotax. On my last several flights, with temps 60-75F, oils 148-180F

Oh, hell yes. My oil temps are consistently 225-240°F here in Georgia in the Summer, and I get 245°F in a hard climb and have to step climb in the dead of Summer. Roger Lee told me not to worry unless it gets over 250°F; I try to mitigate if it hits 245.

When you start getting air temps above 80°F you will see higher oil temps. It also depends on your field elevation and cruise altitudes. The CHTs stay pretty cool on the Rotax because of liquid cooling.

MrMorden wrote:

Sling 2 Pilot wrote: May I ask? Does anyone flying a Rotax ever see temps above 212F consistently? It’s got to be near 100 on the ground, as Inrecall. Remember, I’m a short timer flying the Rotax. On my last several flights, with temps 60-75F, oils 148-180F

Oh, hell yes. My oil temps are consistently 225-240°F here in Georgia in the Summer, and I get 245°F in a hard climb and have to step climb in the dead of Summer. Roger Lee told me not to worry unless it gets over 250°F; I try to mitigate if it hits 245.

When you start getting air temps above 80°F you will see higher oil temps. It also depends on your field elevation and cruise altitudes. The CHTs stay pretty cool on the Rotax because of liquid cooling.

Thanks MrMorden, I was above 200 on my cross country from CA to NY, but as of late, just seeing the temps posted above. Also, my newer Rotax 912 ULS, only has a coolant readout, no individual CHT’s. I do have four EGT’s.

Sling 2 Pilot wrote: Thanks MrMorden, I was above 200 on my cross country from CA to NY, but as of late, just seeing the temps posted above. Also, my newer Rotax 912 ULS, only has a coolant readout, no individual CHT’s. I do have four EGT’s.

Yesterday ground OAT was 94°F (940ft field elevation), and my cruise oil temps were 220°F to 230°F at low altitude (2000ft or less AGL). I hit 245°F in a climb to 4500ft. Once I got above 3000ft or so the temps stopped going up, and if I kept climbing they probably would have gone down a bit even while still climbing. When I leveled out the temps went back down to 230°F pretty quickly. If I was going a long distance I would have climbed to 6500 or higher and cruise temps would have probably stayed easily at 210-220°F or so.

Cirrus engines tended to generate a watery, milky sludge in the oil cap/dipstick.

It was put forth that removing the oil cap while securing the plane allowed water vapor/steam to escape. Of course, one needed protocols in place to ensure the cap made it back in place before the next flight.

Not saying it’s something we should start doing with the ROTAX, but just food for thought.