Skaugi Posted July 6, 2019 Report Posted July 6, 2019 dropped my exhaust on my M20k 1979 and saw this little gem dangling with no broken wire in sight. The attached line is an oil line that goes to the turbo. Looks like some sort of pressure switch but coming off the turbo seems weird to me. Please help......this is going to bother me, I don’t like dangling things on an airplane. Quote
MIm20c Posted July 6, 2019 Report Posted July 6, 2019 Might be an oil pressure sensor. If no pressure is present it might have a warning light that emits. Quote
carusoam Posted July 8, 2019 Report Posted July 8, 2019 @Skaugi it’s been a few days... Might be wise to look at all the detail on the sensor itself...anything legible on the label...? i see the words 0-10 Barr on part of it... it may have a Rochester part number too... Based on what I see that may be a pressure sensor? 10 Barr is 145psi according to Alexa... sound familiar? Get the part number from it and identify if it may be an oil P sensor... typical range...matches. Expect Something is missing it’s sensor and won’t give a reading when turned on... depending on failure mode selected, it may go to full scale when disconnected... or zero... Got a JPI? Or is this an ordinary ship’s sensor... Turbos and oil pressure sensors, don’t usually go together... they should, but they don’t... There is a wire end there somewhere... keep looking for it. PP thoughts only, not a mechanic... Best regards, -a- Quote
Skaugi Posted July 8, 2019 Author Report Posted July 8, 2019 Definitely appreciate the responses. I have a JPI 711 installed on the airplane and all works like it should. Maybe when the JPI was installed there was a different pressure sensor installed at a different location. It does make sense to me that this could be some sort of temp sensor because it is installed on the hottest part of engine (turbo). Ill keep researching but I really appreciate the feedback. Quote
PT20J Posted July 8, 2019 Report Posted July 8, 2019 Is it in the illustrated Parts Catalog? If not, is there a logbook entry for its installation? Can you read the numbers on the label? If so, you should be able to look up the part number and find out what kind of a sensor it is. If it's not in the IPC, not part of an STC and unused, it should be removed. Quote
carusoam Posted July 8, 2019 Report Posted July 8, 2019 Quite often, having a JPI you may get duplicate sensors... for temps and pressures... It really helps to know where each sensor is mounted... and where displayed... https://www.aircraftspruce.com/catalog/inpages/EDM711.php and https://www.jpinstruments.com/shop/edm-700/ The above links show details for the 711... I believe the 711 is specific to a 700 series for a six cylinder engine... but looks like JPI dropped the name in later installs... Looks like the way JPI works.... is confusing to the new owner. On start-up of the Jpi... it searches for all the sensors... and only reports the ones that it finds... The day the wire became disconnected it simply stopped reporting it... If you aren’t watching the scroll of data all the time you won’t notice it missing... To determine how long the wire has been disconnected.... download the data from the JPI.... It should show in the earlier flights and then be missing in the later ones... Check you AC logs to see when the JPI was installed, it will probably list all of the various sensors that were installed. it is possible that the same sensor model is installed for the ship’s sensor, and the JPI’s sensor... PP thoughts only, not a mechanic... Best regards, -a- Quote
jaylw314 Posted July 8, 2019 Report Posted July 8, 2019 5 hours ago, Skaugi said: Definitely appreciate the responses. I have a JPI 711 installed on the airplane and all works like it should. Maybe when the JPI was installed there was a different pressure sensor installed at a different location. It does make sense to me that this could be some sort of temp sensor because it is installed on the hottest part of engine (turbo). Ill keep researching but I really appreciate the feedback. If you have a 711, that is the same as an EDM 700 but primary for (depending on the options selected) CHT, oil temp and TIT. so I suspect that is the factory oil temp sensor, and a new one compatible with the EDM 711 was installed elsewhere. That suggests you have the oil temp primary option on your EDM 711 1 Quote
Skaugi Posted July 8, 2019 Author Report Posted July 8, 2019 Ok both my oil pressure gauges work on the EDM and the instrument cluster. The single wire at the end of the sensor had been pulled out at sometime and i cant find it anymore so maybe it was just removed with the installation of the EDM. Thank you all for the help. Quote
N231BN Posted July 8, 2019 Report Posted July 8, 2019 (edited) I'll be more detailed this time. That is the factory oil pressure sender. It is supposed to be clamped to the engine mount tube above the co-pilot's foot well. The reason it is attached to the turbo is the location normally used on the crankcase for oil pressure is used to supply oil to the turbocharger. Edited July 8, 2019 by N231BN 1 Quote
carusoam Posted July 8, 2019 Report Posted July 8, 2019 Now... it is time to find the other OilP sensor to see if it has been wired to the two different gauges... using a voltage signal, it may be possible to supply two different gages with one sensor... The 711 is primary for some things... (But, I didn’t see OilP on the list) It makes a crummy display, because button pushing is required to get the data quickly... Best regards, -a- Quote
jaylw314 Posted July 8, 2019 Report Posted July 8, 2019 I don't believe the EDM 711 has the option of an oil pressure input? Quote
carusoam Posted July 8, 2019 Report Posted July 8, 2019 Jay, See the list I posted for the 700 series... 711 is listed, so it applies... it has OilP as a sensor option... May not be primary though...? The AS link doesn’t show all the sensors for some reason... Best regards, -a- Quote
CaptRJM Posted July 8, 2019 Report Posted July 8, 2019 Most certainly the factory oil pressure sender that feeds the ships stock gauge. It is a Bosch 0-10 Bar (atmosphere) that is relabeled. It should not be dangling around! Mine is has a clamp that secures it to the engine mount Quote
N231BN Posted July 8, 2019 Report Posted July 8, 2019 Ok both my oil pressure gauges work on the EDM and the instrument cluster. The single wire at the end of the sensor had been pulled out at sometime and i cant find it anymore so maybe it was just removed with the installation of the EDM. Thank you all for the help. If that is disconnected and your factory gauge still works, you should figure out where the sender is that is feeding your factory gauge. If they are using the front location (by the governor) it won't give you an accurate indication of oil pressure to the turbo which is important. Quote
jaylw314 Posted July 8, 2019 Report Posted July 8, 2019 3 hours ago, carusoam said: Jay, See the list I posted for the 700 series... 711 is listed, so it applies... it has OilP as a sensor option... May not be primary though...? The AS link doesn’t show all the sensors for some reason... Best regards, -a- Hmm. I was looking at my install manual for the 711, and I didn't find an oil pressure option in there? My install manual may be out of date...or my glasses Quote
carusoam Posted July 9, 2019 Report Posted July 9, 2019 Install manuals are for installing.... hard to understand for ordinary PPs without assistance.... Go with the pilot’s manual for the 711... much easier for the PP to cope with. There is a chart... that lists all the sensors. Some are listed as optional... The 711 appears to be a very capable device... Unfortunately, it can be primary for most of the Temps but not so for the others on the list... There is also an STC document that may describe the Primary situation a touch better... From the JPI site... the file name looks to add some confusion as well... it covers 700, 800, and 711... https://www.jpinstruments.com/wp-content/uploads/2012/10/PG-EDM-800-Rev-X-pls-110817.pdf Wonder if I can use the Primary 12 CHT & EGT sensors with a JPI900... That would save hours of install time... PP thoughts only, JPI also has the install guides posted... Best regards, -a- Quote
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