---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Wed 06/21/17: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:41 AM - Re: Variable Oil Pressure Reading (rampil) 2. 06:05 AM - Re: Variable Oil Pressure Reading (Roger Lee) 3. 10:20 AM - Re: Variable Oil Pressure Reading (JohnF) 4. 01:56 PM - Re: Variable Oil Pressure Reading (Roger Lee) ________________________________ Message 1 _____________________________________ Time: 05:41:25 AM PST US Subject: RotaxEngines-List: Re: Variable Oil Pressure Reading From: "rampil" Hi Barry! Cavitation requires massive pressure changes usually caused by flow in hydrodynamic systems, high speed flow and shear. There is essentially no flow in a dead end tube to a pressure diaphragm. If there is a bubble, maybe you will get a bit of to-and-fro, but not the kind of shear to create cavitation. Same reason bends really don't affect pressure transducer lines. Small pressure changes like 0 to 60 psi would have to occur with huge acceleration to cavitate oil, a fluid designed to have high surface tension. Adding a length of tubing increases inertance and a wee bit of resistance. Burping these engines is all about refilling the reservoir and preventing entrained bubbles from blocking oil channels in the block which would depress lubrication and heat transfer. Nothing to do with resonance phenomena. -- If you can't measure something accurately, you can't understand it: paraphrased from Lord Kelvin For the curious, check out the electrical analog, a pi filter here at https://en.wikipedia.org/wiki/Capacitor-input_filter -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470322#470322 ________________________________ Message 2 _____________________________________ Time: 06:05:42 AM PST US Subject: RotaxEngines-List: Re: Variable Oil Pressure Reading From: "Roger Lee" Hi John, You didn't say if you did a full oil purge? If you didn't you still need to do one before a flight. Yes air in the system can cause pressure swings and sometimes after a purge, but should go away. -------- Roger Lee Tucson, Az. Rotax Instructor & Rotax IRC Light Sport Repairman Home 520-574-1080 TRY HOME FIRST Cell 520-349-7056 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470323#470323 ________________________________ Message 3 _____________________________________ Time: 10:20:38 AM PST US Subject: RotaxEngines-List: Re: Variable Oil Pressure Reading From: "JohnF" Thanks for your suggestions/ideas. As I suspected last evening at home while thinking over the problem it struck me that when doing the air purge after replacing fuel and oil hoses that upon reflection that evening that I had "pumped" a lot of oil out of the engine while doing the purging. I had originally put in 3-liters of new Aeroshell Sport Plus 4, but I suspected I had emptied too much while purging. This morning I refilled the oil to the top of the flats on the oil dip stick, purged the oil system again, buttoned up the plane, and ran it up. One thing I wanted to do is monitor the operation of the Thermostasis unit. It worked perfectly, and got me up to 50-degrees C in a few minutes, high enough to apply takeoff power if need be. The oil pressure was rock solid, moving from 66psi/81-degrees F, to 55psi-122-degrees F in those 3 or 4 minutes. Problem was low oil quantity...now fixed. Reminds me what a mechanic once told me: If you have a problem, look at the last thing you did. Seems good advise still. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470333#470333 ________________________________ Message 4 _____________________________________ Time: 01:56:02 PM PST US Subject: RotaxEngines-List: Re: Variable Oil Pressure Reading From: "Roger Lee" Hi John, Glad it worked out. I usually put in 3.5 liters for a good oil purge. One thing about the oil purge is you don't need a lot of oil to come out. A small quantity is fine. You're just trying to make sure the lifters have oil and there are no huge air voids in the engine. It doesn't take that much excess oil to do that. If you run low on oil during a purge you can pump air into the system and cause those air voids. -------- Roger Lee Tucson, Az. Rotax Instructor & Rotax IRC Light Sport Repairman Home 520-574-1080 TRY HOME FIRST Cell 520-349-7056 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470346#470346 ------------------------------------------------------------------------------------- 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.