FlyingMonkey Posted November 23, 2014 Report Share Posted November 23, 2014 Once again, after months of perfect 40-50psi operation, my oil pressure started reading low again today. It was 30psi most of the flight, and dipped at times to 18-20psi. This is the third crappy VDO sender on the airplane in 18 months, it has been relocated to the firewall using the Lockwood kit, and has dual grounds including one directly to the battery negative terminal. I also have the new mushroom oil pressure regulator part installed. I checked, cleaned, and tightened all connections, but it still reads ~30psi in flight. Is there anything I can do other than replace the sender again? Bang on it with a hammer maybe? ???? Can colder weather be affecting it? It was perfect all summer and fall until today. Link to comment Share on other sites More sharing options...
Tom Baker Posted November 23, 2014 Report Share Posted November 23, 2014 You can remove and test the sender to see if really is bad. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 23, 2014 Author Report Share Posted November 23, 2014 You can remove and test the sender to see if really is bad. What would be the test procedure for the sender? Another possibility is a bad gauge...I do have a spare factory gauge that could be swapped in for testing. Link to comment Share on other sites More sharing options...
Roger Lee Posted November 23, 2014 Report Share Posted November 23, 2014 Just pick up a test gauge and tubing at Ace Aviation for around $20 and put it inline and check the system and see if it is the sender. Most likely it is that or a bad connection. You can remove the screw plug just in front of the regular oil pressure sending port down by the oil pump. You'll know real quick what is going on. Link to comment Share on other sites More sharing options...
Dan Kent Posted November 23, 2014 Report Share Posted November 23, 2014 You could go with a Kavlico 101693-000 from Dynon ($85). I believe your panel has a 5V source as the sensor has 3 wires. At least that's how it was when I got their fuel pressure sensor. Pg 20 of http://dynonavionics.com/downloads/order_form.pdf I believe Dave (S3flyer) had this installed and he doesn't have the SV system, so I think the 5V is available from non SV Dynon systems. If possible, you may want to get the fuel pressure sensor also. Mine is rock solid. Link to comment Share on other sites More sharing options...
Tom Baker Posted November 23, 2014 Report Share Posted November 23, 2014 Remove the sender and test it on the bench using a compression tester. Buy a 1/4" to 1/8" pipe thread adapter and screw a air hose fitting in it that will plug into the compression tester. You can use the one that is screwed into the fitting that screws into the sparkplug hole, or you can get another one. Plug the sender into the compression tester and increase the air pressure while taking readings with a ohm meter. If you search I have posted a chart showing the ohm readings that relate to the given pressures. By dialing up the pressure slowly you can chart the ohms up the chart, and see if there is a bad spot on the sender. I edited to change bushing to adapter. Link to comment Share on other sites More sharing options...
Tom Baker Posted November 23, 2014 Report Share Posted November 23, 2014 You could go with a Kavlico 101693-000 from Dynon ($85). I believe your panel has a 5V source as the sensor has 3 wires. At least that's how it was when I got their fuel pressure sensor. Pg 20 of http://dynonavionics.com/downloads/order_form.pdf I believe Dave (S3flyer) had this installed and he doesn't have the SV system, so I think the 5V is available from non SV Dynon systems. If possible, you may want to get the fuel pressure sensor also. Mine is rock solid. He has analog engine gauges. He would have to create a 5V source, and it still might not work with his gauge. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 23, 2014 Author Report Share Posted November 23, 2014 Thanks guys..when I have some free time over the holiday week I will fully investigate. Link to comment Share on other sites More sharing options...
WmInce Posted November 23, 2014 Report Share Posted November 23, 2014 Thanks guys..when I have some free time over the holiday week I will fully investigate. Seriously, I am very impressed with the resources available on this forum. There are some very experienced people. Thanks to all of you who contributed. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 26, 2014 Author Report Share Posted November 26, 2014 Looking things over and wanting to do the easiest fixes first, we found that the oil pressure sensor wire had a loose connection. A new ring terminal was crimped in place. We then taxied around the airport for some time, including some run ups, letting the engine and oil get fully warm. Pressure stayed 40-50psi the whole time. I'm hoping this is the answer, I will fly a bit in the next couple of days to confirm the fix. Link to comment Share on other sites More sharing options...
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