High Oil Pressure?
New to Rotax ownership. My plane has a Rotax 912 ULS (circa 2007 vintage, serial number 5649159). It lived the first 65 hours of it's life at higher altitudes (Montana) and likely much colder temperatures. I'm running AeroShell Sport Plus 4 oil, and the standard ROTAX oil filter. I've flown it about 20 hours since purchasing it, and am just about ready for my first 25-hour oil change. I had all the hoses (oil, fuel, etc.) replaced as part of the purchase, because they were 13 years old. I put 16.5 hours on the plane flying it home from Utah to the Dallas area, and had no engine oil pressure warnings. But when I had time to go through the "settings" on the GRT EIS 2004 system, the oil pressure high warning was set to 90 PSI instead of the 73 PSI I would have expected (normal range is 29-73 PSI according to the Rotax 912 ULS manual). So I changed that warning threshold to 73 PSI, and started monitoring the oil pressure more closely on the next couple of flights.
Since changing that warning threshold, I've noticed the oil pressure readings seem to be on the high side of the normal range pretty much all the time. With the lower "warning" threshold, I'm getting occasional High Oil Pressure warnings from the EIS. My first two flights were very short duration, and I only saw those warnings at idle RPM (or slightly above), with the oil pressure reading as high as 80 PSI near idle, and decreasing as the RPM increased, so that at 3500 or above, it was in the upper 60's.
On my last flight (which was about 2 hours in duration), the oil pressure seemed to stabilize at the higher end of "normal" range (right around 70 PSI). But when I decreased the power for landing, the High Oil Pressure warning alerted again, and the oil pressure was reading 80 PSI at near idle RPM.
I've read through some of the "oil pressure" posts on this forum, and it appears that the most likely culprit is either the sender unit, or the spring/ball in the pressure regulator itself. I will also check for loose or corroded ground (though the symptoms appear to be reversed from the typical grounding issue).
Is there anything else I should be checking? I know people have mentioned that the VDO gauge itself could be at fault, but the GRT EIS 2004 would appear to be working normally for everything else, so I don't think that could be the problem.
Thanks! – Jim Parker
