Joe Larussa Posted August 15, 2018 Report Share Posted August 15, 2018 I have a 77 M20J and the oil pressure gauge has starting twitching. Not digging it. It’s one of those cluster gauges where the oil line connects at the rear. Temp is totally normal. Thoughts? Quote Link to comment Share on other sites More sharing options...
Joe Larussa Posted August 15, 2018 Author Report Share Posted August 15, 2018 15 minutes ago, bluehighwayflyer said: I have one if you decide you want to replace your OEM gauge. Good luck with your diagnosis. Jim You have my interest! Quote Link to comment Share on other sites More sharing options...
Yetti Posted August 15, 2018 Report Share Posted August 15, 2018 You may need to add a quart of oil. Mine will do that when it needs oil. Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted August 15, 2018 Report Share Posted August 15, 2018 (edited) It is unlikely that the mechanical gauge is twitchy. When the oil pressure gets twitchy it usually means that the oil pickup is sucking in air. This can be caused by low oil level, a leaking suction screen or the gasket between the sump and the accessory housing is leaking. It could also be the oil pump itself. If it is an electrical gauge then a bad wire can make it twitchy. Edited August 15, 2018 by N201MKTurbo Quote Link to comment Share on other sites More sharing options...
flyboy0681 Posted August 15, 2018 Report Share Posted August 15, 2018 Just now, N201MKTurbo said: It is unlikely that the mechanical gauge is twitchy. When the oil pressure gets twitchy it usually means that the oil pickup is sucking in air. This can be caused by low oil level, a leaking suction screen or the gasket between the sump and the accessory housing is leaking. Which is exactly what happened to me two years ago. The needle was "twitching", but never headed into the red. When I shut down and checked the dipstick it showed - nothing. 1 Quote Link to comment Share on other sites More sharing options...
Igor_U Posted August 15, 2018 Report Share Posted August 15, 2018 3 hours ago, flyboy0681 said: Which is exactly what happened to me two years ago. The needle was "twitching", but never headed into the red. When I shut down and checked the dipstick it showed - nothing. Where did oil go? Quote Link to comment Share on other sites More sharing options...
flyboy0681 Posted August 15, 2018 Report Share Posted August 15, 2018 15 minutes ago, Igor_U said: Where did oil go? Into the ether. There was no oil in the case, there was no oil underneath and there was no oil within the cowl. The tear down revealed a stuck exhaust value, which means we were trailing smoke for quite a distance. Quote Link to comment Share on other sites More sharing options...
Joe Larussa Posted August 16, 2018 Author Report Share Posted August 16, 2018 16 hours ago, Yetti said: You may need to add a quart of oil. Mine will do that when it needs oil. How low on oil are you when that happens? Quote Link to comment Share on other sites More sharing options...
Joe Larussa Posted August 16, 2018 Author Report Share Posted August 16, 2018 So I tried a different oil pressure gauge with the same twitchy results. Then I landed and hooked the stock one back up. I added one quart of oil and it was solid as a rock. I had 6 quarts when I started. Heck if I know. 1 Quote Link to comment Share on other sites More sharing options...
Guest Posted August 16, 2018 Report Share Posted August 16, 2018 (edited) 17 hours ago, flyboy0681 said: Into the ether. There was no oil in the case, there was no oil underneath and there was no oil within the cowl. The tear down revealed a stuck exhaust value, which means we were trailing smoke for quite a distance. With a stuck exhaust valve was the engine vibrating? Clarence Edited August 16, 2018 by M20Doc Quote Link to comment Share on other sites More sharing options...
flyboy0681 Posted August 16, 2018 Report Share Posted August 16, 2018 2 hours ago, M20Doc said: With a stuck exhaust valve was the engine vibrating? Clarence Not one bit. As a matter of fact, I was flying that day with a buddy who flies for American and is an A&P and he didn't notice anything until the needle started dancing around. Quote Link to comment Share on other sites More sharing options...
Yetti Posted August 16, 2018 Report Share Posted August 16, 2018 14 hours ago, Joe Larussa said: How low on oil are you when that happens? Starts when it gets below 5 quarts Quote Link to comment Share on other sites More sharing options...
carusoam Posted August 16, 2018 Report Share Posted August 16, 2018 That describes an OilP sensor with an alternate oil level indicator. Two people indicate oil levels below 5qts allows air into the oil pick up line... with the addition of a quart of oil, the OilP readings stabilize again... Joe, have you added a JPI to your panel yet? Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Joe Larussa Posted August 16, 2018 Author Report Share Posted August 16, 2018 Just now, carusoam said: That describes an OilP sensor with an alternate oil level indicator. Two people indicate oil levels below 5qts allows air into the oil pick up line... with the addition of a quart of oil, the OilP readings stabilize again... Joe, have you added a JPI to your panel yet? Best regards, -a- I do have a EDM 700 but it doesn't have oil pressure hooked up yet. Was thinking of switching to the EDM 730. Quote Link to comment Share on other sites More sharing options...
flyboy0681 Posted August 16, 2018 Report Share Posted August 16, 2018 Just now, carusoam said: Joe, have you added a JPI to your panel yet? After this little incident (which cost > $30k), we had the oil pressure option added to the JPI 700. Imagine that, if we had the $265 sensor installed at the time, it may have saved over thirty grand. 2 Quote Link to comment Share on other sites More sharing options...
carusoam Posted August 16, 2018 Report Share Posted August 16, 2018 JPI has a few instruments that are great for integrating all the data from the usual sensors and include the FF and GPS data... Just use caution, if you have a plan to go certified 900/930 that uses a handful of different certified sensors. So if you plan on using your J as a forever-plane... certified is a great way to go... Or the 830(?) which is very similar with a color screen and updated graphics and faster processor (data points per time)... just not certified... Or see how much you can integrate with the existing 700... as old as it is... it is very capable. Including FF and GPS, I believe... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
flyboy0681 Posted August 16, 2018 Report Share Posted August 16, 2018 Our 700 has the fuel flow option, which is accurate almost to the ounce, which feeds into the GTN 750 fuel utilities page. We also added the oil temperature probe. 1 Quote Link to comment Share on other sites More sharing options...
Joe Larussa Posted August 16, 2018 Author Report Share Posted August 16, 2018 I Have oil temp just not pressure. Was going to add it but now thinking 730. Quote Link to comment Share on other sites More sharing options...
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