Costa Leite Posted September 26, 2021 Report Posted September 26, 2021 Dear All Yesterday I went to the hangar to wash our 1998 M20J Allegro. After the wash I went for a short local flight to dry the aircraft. After departure I imediatly notice a High Oil Temperature indication, around 220º, on SigmaTec gauges. I then double checked the JPI 700 indication, and it was normal at 190º. OAT was 20º on this gusty day. I then checked CHT temp and they were also normal, around 360º, and Oil Pressure was also normal and in green. While I reduced engine setting for cruise flight at 1000´AGL, I also selected cowl flaps full open. But the Oil Temp remained really high during all flight, reaching a maximum of 240º on gauge, but they kept normal on JPI 700, reaching a maximum of 195º, and the CHT and Oil Pressure remained normal during all flight, both on gauges and on JPI. So, I am guessing this can be a Oil Temp Sensor - Venatherm problem?? Any other thoughts on what can be the cause of this problem? Is it possible to clean/fix something in the Vernatherm? Or maybe is it time to buy a new one? Can anyone share the partnumber and tips on where to but it? (PS: I send below pictures of the gauges after shutdown, and thats why the Oil Pressure is showing a bit lower than normal.) Cheers Fredi Quote
PT20J Posted September 27, 2021 Report Posted September 27, 2021 1. Those look like Sigma-Tek gauges. I don’t think Mooney used Moritz gauges until 1999 after M20Js were out of production. 2. If all other indications were normal, why would you suspect the vernatherm rather than the gauge? I would verify the accuracy of the factory gauge before doing anything else. Skip 1 Quote
carusoam Posted September 27, 2021 Report Posted September 27, 2021 Great news… those aren’t the befallen Moritz gauges…. Moritz have digital displays at the bottom of each instrument… So… 1) Check to see if you have two different OilT sensors…. Probably do… 2) When the ships OilT gauge goes higher than usual… the responding OilP gauge should be reading lower than usual… 3) The JPI OilT sensor is probably in a different location than the ship’s gauge… in the past, did they read similarly? 4) The vernatherm health is an interesting thought… but, it alters the oil temperature universally… 5) Now you have some sleuthing to do… where are the two OilT sensors located? 6) Did the ship’s OilT sensor get moved from its normal location for any reason? 7) Good probability that the OilT sensor is a thermistor… and it may be starting to fail… 8) Thermistors are easy to test… ice water and boiling water, and check their response… 9) know that thermistors don’t last forever… unfortunately… 10) My experience… my OilT thermistor gave up the ghost, slowly…. Getting it replaced required making a friend of an MSer in Canada going through a JPI upgrade…. If for some reason you need a new OilT sensor… find out which one it is… lead times may be in months… PP thoughts only, not a mechanic… Best regards, -a- Quote
Costa Leite Posted September 27, 2021 Author Report Posted September 27, 2021 Sorry that I confused Moritz with Sigma Tek. Of course I don’t have Moritz and do have sigma-tek gauges. Historically, the two readings are very similar, and the JPI usually shows 5° lower temps. Our mechanic once told me that the ship OilT sensor is located on the oil line that goes to the Oil Cooler and the JPI sensor is located on the oil line that exit the cooler, and so this was the reason for the slight difference between them. We never touched these sensors ever! I don’t really understood what the vernatherm was doing but right now I figured out! Thanks. So, I agree it must be something with the SigmaTek gauge or with its sensor, because all other readings are totally normal. 2 Quote
PT20J Posted September 27, 2021 Report Posted September 27, 2021 Good news the gauges are Sigma-Tek since I believe those can still be repaired. More likely it is the sender, however. Your mechanic isn’t quite correct: it would be a poor oil cooler if it only lowered the oil temperature by 5 deg The factory sender is located near the oil filter. The JPI sender should be located at the front on the engine. Both locations are after the oil cooler. They agree within a few degrees on my 1994 M20J with Sigma-Tek gauges. The oil in the sump is perhaps 40 deg or so hotter. That’s good because you want it hot enough to boil off any water that forms as a product of combustion or from condensation. Skip 2 Quote
Costa Leite Posted September 27, 2021 Author Report Posted September 27, 2021 Thanks Skip! I always wondered why the cooler only reduced 5°?! Buy it sounds logically now that the JPI sender is slight fresher because of its position. Does anyone knows the PN of this sender? Quote
PT20J Posted September 27, 2021 Report Posted September 27, 2021 1 hour ago, Costa Leite said: Thanks Skip! I always wondered why the cooler only reduced 5°?! Buy it sounds logically now that the JPI sender is slight fresher because of its position. Does anyone knows the PN of this sender? Sure, glad to help. The parts catalog lists a Rochester 3080-37. https://www.aircraftspruce.com/catalog/inpages/rochoiltemp.php Skip Quote
carusoam Posted September 28, 2021 Report Posted September 28, 2021 Great details Skip! The Rochester details at Spruce also include a chart of temp vs. resistance… Something that can be checked by the mechanic…. (Or the owner) Chances are, you can prove the sensor has gotten a bit faulty… Best regards, -a- 1 Quote
Costa Leite Posted September 28, 2021 Author Report Posted September 28, 2021 Thanks a lot to both of you!! I will trace this issue and post here the results, as always. Cheers, Fredi Quote
PT20J Posted September 28, 2021 Report Posted September 28, 2021 Just saw this article that may be of interest. https://www.kitplanes.com/bad-indication-or-a-real-problem/?utm_source=ActiveCampaign&utm_medium=email&utm_content=KITPLANES+Weekly&utm_campaign=KP+Weekly+2021%2F09%2F21 Skip 1 Quote
Guest Posted September 28, 2021 Report Posted September 28, 2021 You can use a “decade box” to simulate different resistance values it the circuit to test the gauge. Clarence Quote
Costa Leite Posted October 6, 2021 Author Report Posted October 6, 2021 It’s interesting that on last couple flights, with 02:00hrs duration each, the OilTempGauge always showed around 30° higher temps than JPI on taxi, take-off and climb, but during cruise the OilTempGauge started to decrease the “error” and showed almost the same temp as JPI, just like before this problem started. Next week our mechanic will test the sender to check its conformity, and I will post here the results. Quote
Costa Leite Posted October 23, 2021 Author Report Posted October 23, 2021 We tested the sender and the gauge. The problem seems to be with the sender, as predicted. But the P/N is not a Rochester 3080-37. It is a NORWICH 102-00066, and these are hard to find :/ Also, the resistance range of this sender is much narrow than topical Rochester senders… is seemed more or less between 100 and 180, in contrast with 30 to 500 range of Rochester Quote
Guest Posted October 23, 2021 Report Posted October 23, 2021 It’s a Norwich, not a MERs it MFRs or manufacturers . Clarence Quote
Costa Leite Posted October 24, 2021 Author Report Posted October 24, 2021 Exactly! Norwich of course. Thanks Clearence for the warning. Do you know where I can find one? I would appreciate very much any help on this chase! Quote
Guest Posted October 24, 2021 Report Posted October 24, 2021 3 hours ago, Costa Leite said: Exactly! Norwich of course. Thanks Clearence for the warning. Do you know where I can find one? I would appreciate very much any help on this chase! I thought that someone replied to you in another thread here. The fellow with the spare mentioned where he sold it. Clarence Quote
Costa Leite Posted October 24, 2021 Author Report Posted October 24, 2021 Actually that was a different part number. But I already send and email to Commodore, but didn’t get any reply yet. I will give them a call tomorrow. Quote
Costa Leite Posted November 4, 2021 Author Report Posted November 4, 2021 Hi All My efforts to find 1x OilSender PN NORWICH 102-00066 for a 98M20J Allegro are not getting any positive result. It’s easier to find Rochester Senders for earlier M20 models, but impossible to me to find Norwich senders. Does anyone have one? Or does anyone have a late J or K, or early Ovation, that is going on digital engine instrument upgrades and might have these spare parts? Many Thanks! Fredi Quote
N201MKTurbo Posted November 4, 2021 Report Posted November 4, 2021 (edited) 1 hour ago, Costa Leite said: Hi All My efforts to find 1x OilSender PN NORWICH 102-00066 for a 98M20J Allegro are not getting any positive result. It’s easier to find Rochester Senders for earlier M20 models, but impossible to me to find Norwich senders. Does anyone have one? Or does anyone have a late J or K, or early Ovation, that is going on digital engine instrument upgrades and might have these spare parts? Many Thanks! Fredi Norwich was acquired by Esterline which was acquired by Transdigm. https://www.transdigm.com/ https://www.auxitrolweston.com/ Here is an old phone number for them, might be worth a call: 1- 607-336-7636 Edited November 4, 2021 by N201MKTurbo Quote
N201MKTurbo Posted November 4, 2021 Report Posted November 4, 2021 I think this is the same sensor: http://www.2040-parts.com/ns-norwich-aero-aircraft-temperature-sensor-probe-102-00002-i996359/ You just need to find a connector for it. I think they are used in Cirrus aircraft. I think they are both nickel RTDs 1 Quote
Costa Leite Posted November 6, 2021 Author Report Posted November 6, 2021 On 11/4/2021 at 11:04 PM, N201MKTurbo said: I think this is the same sensor: http://www.2040-parts.com/ns-norwich-aero-aircraft-temperature-sensor-probe-102-00002-i996359/ You just need to find a connector for it. I think they are used in Cirrus aircraft. I think they are both nickel RTDs Thank you! I am already chasing it Quote
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