---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Mon 07/06/09: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:11 AM - Re: Fuel in oil 912ULS (Thom Riddle) 2. 04:56 AM - Re: Rotax 2 stroke (Catz631@aol.com) 3. 06:34 AM - Re: Rotax 2 stroke (lucien) 4. 09:25 AM - Re: Fuel in oil 912ULS (rampil) 5. 09:41 AM - Re: Fuel in oil 912ULS () 6. 10:10 PM - Re: Fuel in oil 912ULS (K Dilks) ________________________________ Message 1 _____________________________________ Time: 04:11:34 AM PST US Subject: RotaxEngines-List: Re: Fuel in oil 912ULS From: "Thom Riddle" Peter, I think of only two ways that fuel could get into the oil supply. 1)The engine is running so rich that there is raw fuel going into the combustion chambers and mixing into the oil on the cylinder walls. 2) You clean the oil tank with fuel and don't drain it and let it dry completely before refilling with fuel. If there is any other way, it does not come to mind. -------- Thom Riddle Buffalo, NY http://riddletr.googlepages.com/sportpilot-cfi http://riddletr.googlepages.com/a%26pmechanix A complex system that works is invariably found to have evolved from a simple system that works. - John Gaule Read this topic online here: http://forums.matronics.com/viewtopic.php?p=251698#251698 ________________________________ Message 2 _____________________________________ Time: 04:56:14 AM PST US From: Catz631@aol.com Subject: Re: RotaxEngines-List: Rotax 2 stroke LS, Thank you so much for your tips !!!! I will print this page and pass it to the guys today. They are having so much fun with the plane and I don't want them to ruin their day by having to plant the aircraft in a field with an engine failure ! I remember my old two stroke SAAB had a "free wheeling" devicethat disengaged the engine when you coasted with your foot off the pedal. Now I remember what it was for. Dick Maddux Milton,Fl **************Looking for love this summer? Find it now on AOL Personals. ________________________________ Message 3 _____________________________________ Time: 06:34:59 AM PST US Subject: RotaxEngines-List: Re: Rotax 2 stroke From: "lucien" Dick Maddux wrote: > LS, > Thank you so much for your tips !!!! I will print this page and pass it to the guys today. They are having so much fun with the plane and I don't want them to ruin their day by having to plant the aircraft in a field with an engine failure ! I remember my old two stroke SAAB had a "free wheeling" devicethat disengaged the engine when you coasted with your foot off the pedal. Now I remember what it was for. > Yep - the rotax 2-strokes aren't among those that just quit or sieze for no reason, so you can expect lots of hours and hours with just fuel/oil and flying with them and very little if any trouble. A couple other things: - The CHT figures for the air-cooled motors in the 2-stroke manuals are wrong, off by almost 100F hot. The correct operating range is more like 280-330F and I'd call 350F the max. The 503 when broken-in runs around 300F normally, the 447 around 330 or so. The 447 will hit 350F in a climb easy but the 503 takes effort to get that hot. - the most common installation error is too long of a pulse line, the line running from the pulse output on the motor to the pneumatic pump. No longer than a foot and preferably 10" or less is what you want. If this line is too long, no matter what it's made of, the pump won't be driven enough to pump with full effectiveness. You can get totally mysterious fuel starvation events when this line is too long. - the only weakness on the 2-strokes is the crank seals. They start to leak after about 50 to 60 hours, so this requires regular inspection. When you start getting the black fluid collecting under the fan housing, it's time to start planning a teardown/reseal.... LS -------- LS Titan II SS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=251722#251722 ________________________________ Message 4 _____________________________________ Time: 09:25:33 AM PST US Subject: RotaxEngines-List: Re: Fuel in oil 912ULS From: "rampil" I don't know if 1% fuel contamination is actually a problem or outside the expected range for Rotax 9xx. It would seem an inconsequential amount in terms of physical dilution of oil and reducing lubrication but I have no idea as to whether it is relevant chemically. Having an oil thermostat might treat the symptom, but as Thom said the common way gas gets into oil is via leaky rings. The first step in diagnosis would be a compression test to test the rings. It is a required component of the annual inspection anyway. Rotax advises that the compression test should be performed when the engine is close to it usual warm operating temperature so that the rings, cylinders and pistons are in expanded thermal equilibrium. (I tried my engine cold and it tested fine, but others recently observed that their engine leak mightily when cold) Ira (in the midst of my 5yr annual) -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=251775#251775 ________________________________ Message 5 _____________________________________ Time: 09:41:03 AM PST US From: Subject: Re: RotaxEngines-List: Fuel in oil 912ULS Check the fuel pump Diaphram, if its weeping it can allow fuel to enter the gearbox/engine regards ivor ---- Peter Thomson wrote: > I have found my oil analyses consistently show 1.2-1.5% fuel in the oil > sample. > > Other oil properties (Shell Advance Ultra full synthetic, changed at 50 hrs > on > unleaded gas) are fine. Engine runs quite cool, but no moisture in oil. > > Any experiences here ? > > Peter > Zenair CH701SP > Rotax 912 ULS 380 hrs since new > OIl analysis by Blackstone ________________________________ Message 6 _____________________________________ Time: 10:10:18 PM PST US Subject: RotaxEngines-List: Re: Fuel in oil 912ULS From: "K Dilks" The fuel dilution is a feature of using blow by gas to return the oil to the oil tank, there will always be some unburnt fuel in this. The designers take this into consideration so hence the need to get the oil temp up to evaporate the contamination out of the oil. 1% is ok but if you know you are running cool then do something about it. Long runs at low power / idle will accelerate the dilution situation. Worst case is when folks fill up with Jerry cans that have a small amount of diesel fuel , this goes strait to the crank case and in worst cases will increase the volume seen in the oil tank. Kev -------- Austria ............. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=251878#251878 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.