High Oil Pressure proven
in 912 / 914 Technical Questions
6 years ago
I have experienced a sudden, dramatic increase in oil pressure from one flight to the next start up 2 weeks later. Engine details: 912 ULS, 2007 model, 820 hours, SN 5649712. Normal pressure is 43 psi and steady since new. Suddenly on cold start it went to 100 psi. Warming at idle of 2200 rpm it dropped to 78 psi. When warmed up, pushing the throttle up above 2700 rpm caused a sudden pressure drop to 68 psi. When down throttled below 2700 rpm there is a sudden increase to 78 psi. This has been relatively consistent throughout the following steps that I have taken presented in chronological order. Conventional wisdom is that "It's always the VDO gauge or a bad ground." So I put in a new gauge and checked the wiring. I replaced the old style pressure relief valve bolt and spring with the new version but not the ball which looked good. There was some wear on the old spring where the ball has sat for 820 hours. There is no shim below the spring. No change in pressure results so I installed a mechanical gauge and this confirmed that the high pressure was real. I did an oil and filter change and examined the magnetic plug which was almost spotless. I have sent an oil specimen for analysis but won't get the results soon. I have not opened the old oil filter yet for examination of the filter media. The 5 year rubber replacement has been followed with this engine. Something clearly happened but I am at a loss as to how I should proceed.
