romair Posted October 21, 2015 Report Posted October 21, 2015 I'm puzzled by high oil pressures that last for about 10 minutes from start-up. I have seen it as high as 160psi. It will usually go back to normal range after 10 minutes or so, and in cruise it is normal at 66-67 psi. I opened the pressure relief element, the ball looks fine, and the spring has some erosion on one of its sides, but not very significant. I do not think this is an instrumentation problem. Any other ideas for things to look for? Engine is an IO360A3B6D Thanks Quote
RobertGary1 Posted October 21, 2015 Report Posted October 21, 2015 Try verifying it with a calibrated gauge. Our cockpit gauges can go wacky. -Robert 1 Quote
KSMooniac Posted October 21, 2015 Report Posted October 21, 2015 I doubt it could be that high in reality. I'll second the idea to plumb in a good mechanical gauge and see if it is real. Quote
romair Posted October 21, 2015 Author Report Posted October 21, 2015 The monitor is an EI mvp 50. While I understand the doubts about that being real, it does not make sense that frequently on start up the oil pressure goes haywire, then during flight it is within normal without going high again until the next flight. Why would the gauge be inaccurate only at the beginning? Quote
KSMooniac Posted October 21, 2015 Report Posted October 21, 2015 Perhaps something is getting hot or moving after the engine warms up? You could ask EI as I've read their tech support is very good. What does that system use for oil pressure sensing? Quote
romair Posted October 21, 2015 Author Report Posted October 21, 2015 Here is an example where the oil pressure goes all the way up to 140 psi. Things are fairly unstable initially, then the rest of the flight quite stable. Quote
Bob_Belville Posted October 21, 2015 Report Posted October 21, 2015 I'll be interested in what some of our engine gurus have to say. I replace the oil pressure adjustment spring with the next size up to get cruise OP into the middle of the green range and now the OP spike like your graph for a few minutes or less. Max for me is closer to 100 psi. Quote
N601RX Posted October 21, 2015 Report Posted October 21, 2015 (edited) I would check the electrical connections at the sensor and if you don't find anything send the above plots to EI and ask their opinion. I don't believe it is possible for oil pressure to go that high especially at low rpm. Edited October 21, 2015 by N601RX 1 Quote
RobertGary1 Posted October 22, 2015 Report Posted October 22, 2015 I'm skeptical that your pressure is really that high. But Lycoming says the danger of high pressure (aside from a possible indication of a problem) is that you can damage seals etx. -Robert Quote
carusoam Posted October 22, 2015 Report Posted October 22, 2015 (edited) A lot of transitions from start up to run-up to take-off in that graph? best regards, -a- Edited October 22, 2015 by carusoam Quote
Seed3r Posted October 22, 2015 Report Posted October 22, 2015 Looks like fun Lets try this, Looking at the graph i can see startup, then at min 5 higher power taxi or warmup attempt, min 8 runup, min 10m takeoff... Drops in preasure correspond with hikes of MAP and FUel flow, so when u make engine work and cycle the oil around the system do you have oil temp graphed as well ? Quote
Yetti Posted October 22, 2015 Report Posted October 22, 2015 Sound like the upper limit is being hit which would be a loose wire or a short Quote
carusoam Posted October 22, 2015 Report Posted October 22, 2015 (edited) Things that things that effect the oilP... 1) Oil T. The warmer it gets, the Lower the viscosity becomes. What oil are you using? What is the OAT lately? 2) There is an oil cooler by-pass. There is an oil temp that opens the by-pass and sends the oil through the cooler. If the oil's heat exchanger/radiator is blocked that could cause some pressure issues. A mechanic can easily rinse out the oil lines and determine if there is a blockage there. 3) I believe there is also a settable valve that a mechanic can adjust to set the oil pressure for the engine. Essentially a flow resistor at the end of the oil's long path. The ball and spring mentioned a couple of times above. 4) Blocked oil screens. Most sensitive to cold oil. It Would be best to identify that the pressure gauge is calibrated before making any changes or cleaning things out that don't need it. Since, it only happens at start-up and doesn't continue after things warm up. I would be looking to the POH for some real answers. What are the top and bottom of the green arc for OilP. Does the ship's OilP gauge match the EI MVP's? Or has the ship's gauge been removed? Some other odd questions that come to mind.... - Is there an OilP redline? - What happens when the OilP is too high? Keep in mind, I am only a PP and not a mechanic. Best regards, -a- Edited October 22, 2015 by carusoam 1 Quote
romair Posted October 23, 2015 Author Report Posted October 23, 2015 Here it is graphed with oil temp. Yes, there is a oilP redline and this is far exceeding it... I live in Tx - outside temps have been quite warm. Also, this is a new behavior. The ball and spring have been inspected, look okay except some mild scoring on the spring on one side (not sure why), but I have a new one ordered. The ship's gauge has been removed. Quote
Guest Posted October 23, 2015 Report Posted October 23, 2015 You need to install a mechanical test gauge in parallel with the line to,the transducer to do a comparison. I think it is likely a faulty transducer or wiring fault. Clarence Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.