---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Sat 06/25/11: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:21 AM - Re: Low oil Pressure Indication Test Results (john firth) 2. 02:11 PM - Re: Low oil Pressure Indication Test Results (Hugh McKay) ________________________________ Message 1 _____________________________________ Time: 01:21:10 AM PST US From: john firth Subject: Re: RotaxEngines-List: Low oil Pressure Indication Test Results Hello Hugh, have you a voltmeter to monitor the system voltage whilst doing the tests. It is possible that changing voltage could affect the reading of an electrical gauge. Cheers, john firth. G-JULZ On 24 Jun 2011, at 01:07, Hugh McKay wrote: > Alright guys, I hope I don=92t screw things up again. Here are the results (attached as a word document) of the final (on the ground) test to reconcile the difference between the VDO electric oil pressure gauge readings in the cockpit (which reads in bars) vs. a direct mechanical oil pressure gauge readings. I had a 1/8=94 line coming directly from the engine port where the oil pressure sender unit is normally attached out to a tee where I attached a new (Lockwood) oil pressure sending unit which was connected to the VDO gauge in the cockpit, and then reduced down to a very small nylon tube connecting to a mechanical oil pressure gauge (range 0-100 psi). The conditions of the test were 455 hours on the engine, engine has the Rotax replacement oil pressure regulator parts installed (new mushroom head, spring and cap screw), ambient temperature was 79 degrees F, oil is Mobil 1 Racing 4T, plane level and tied down securely. =46rom these results I am satisfied that I do NOT have a low oil pressure problem in my engine. > > Because the pressure sending unit is brand new, I do not believe that is the problem causing low pressure readings on the VDO gauge in the cockpit. =46rom these results I suspect I have either a VDO gauge that has gone bad, or a grounding/partial grounding problem. Any comments?? > > Hugh G. McKay III, P.E. > Senior Consultant > Worldwide Engineering Inc. > 4090 North NC Hwy. 16 > Denver, NC 28037 > Allegro 2000 ELSA > Rotax 912 UL > N661WW > > Ph. 704-661-8271 > Fax 704-483-5466 > email hgmckay@bellsouth.net > http://www.wwegeo.com > ________________________________ Message 2 _____________________________________ Time: 02:11:18 PM PST US From: "Hugh McKay" Subject: Re: RotaxEngines-List: Low oil Pressure Indication Test Results John, Yes I have a volt meter in the plane. Voltage is steady. I am going to pull the panel out enough to get to all the ground connections behind the panel and check all the other grounding points on the plane first to make sure they are all good. If they are all good solid grounds, it would seem to be the VDO instrument itself. The sending unit itself seems to be good because the Mechanical gauge indicated good oil pressure as noted in my tabulated results. The pressure indication on the VDO comes up to 4 bar (58 psig) as soon as the engine cranks. But, within a few minutes while taxing the VDO pressure begins to drop off down to the 2 bar (29 psig). On take off with the engine at max throttle the VDO gauge shows about 3 bar (43.5 psig). At cruise the VDO shows around 2.0 '2.3 bar (29-33.35 psig). I=92ll keep every one posted as I continue to search for the =93gremlin=94! Hugh G. McKay III, P.E. Senior Consultant Worldwide Engineering Inc. 4090 North NC Hwy. 16 Denver, NC 28037 Ph. 704-661-8271 Fax 704-483-5466 email hgmckay@bellsouth.net http://www.wwegeo.com From: john firth Sent: Saturday, June 25, 2011 4:16 AM Subject: Re: RotaxEngines-List: Low oil Pressure Indication Test Results Hello Hugh, have you a voltmeter to monitor the system voltage whilst doing the tests. It is possible that changing voltage could affect the reading of an electrical gauge. Cheers, john firth. G-JULZ On 24 Jun 2011, at 01:07, Hugh McKay wrote: Alright guys, I hope I don=92t screw things up again. Here are the results (attached as a word document) of the final (on the ground) test to reconcile the difference between the VDO electric oil pressure gauge readings in the cockpit (which reads in bars) vs. a direct mechanical oil pressure gauge readings. I had a 1/8=94 line coming directly from the engine port where the oil pressure sender unit is normally attached out to a tee where I attached a new (Lockwood) oil pressure sending unit which was connected to the VDO gauge in the cockpit, and then reduced down to a very small nylon tube connecting to a mechanical oil pressure gauge (range 0-100 psi). The conditions of the test were 455 hours on the engine, engine has the Rotax replacement oil pressure regulator parts installed (new mushroom head, spring and cap screw), ambient temperature was 79 degrees F, oil is Mobil 1 Racing 4T, plane level and tied down securely. From these results I am satisfied that I do NOT have a low oil pressure problem in my engine. Because the pressure sending unit is brand new, I do not believe that is the problem causing low pressure readings on the VDO gauge in the cockpit. From these results I suspect I have either a VDO gauge that has gone bad, or a grounding/partial grounding problem. Any comments?? Hugh G. McKay III, P.E. Senior Consultant Worldwide Engineering Inc. 4090 North NC Hwy. 16 Denver, NC 28037 Allegro 2000 ELSA Rotax 912 UL N661WW Ph. 704-661-8271 Fax 704-483-5466 email hgmckay@bellsouth.net http://www.wwegeo.com ------------------------------------------------------------------------------------- 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.