Oil Temperature Probe = $800??

[Jeff_S]

Hey all,

I've had a flaky oil temp situation for some time now, where it will mysteriously drop out for awhile and then come back.  It's a measurement issue for sure, not an actual oil problem. This is a G1000-equipped plane.  We've changed the connector where the wire from the probe connects to the wires going into the cannon plug. We've cleaned out the cannon plug. Problem still comes and goes. So Savvy (Paul K) suggested the next best troubleshooting step was to change the oil temp probe.  My A/P finally has gotten to this work and after getting a part number from Mooney he's showing a price of $800+ for this little doohickey! That seems like a lot...but hey, it is aviation after all.

Just looking for opinions or other options on how I might get this little doodad to see if it solves the problem. Thanks!

Jeff

[skykrawler]

Seems like it should be a thermistor - changes resistance based on temp.   I would try to verify the sensor is bad by connecting an ohmmeter between the sensor terminal and a ground on the engine while the oil is hot or by removing the sensor and using hot water.

When you say it "drops out" do you mean the indication drops to zero?  If so, this implies an open in the circuit.  Generally these sensors lower resistance as the temp goes up. An analog gauge will read full scale if you ground the sensor wire.

 

[cbarry]

 Not a mechanic, but I would want to rule out a simple grounding issue that may be the cause.

[ArtVandelay]

I had this problem, I fixed it by disconnecting the probe’s leads, cleaning, and reconnecting. With the JPI (I assume yours are similar) the leads of the probes are eyelets and are just bolted to eyelets of the engine monitor wires.

[Jeff_S]

@skykrawler Yes, the signal just drops out completely and the big red X comes up on the G1000. So I agree that wiring would seem the most likely cause, and as I noted we did put in a clean connector and cleaned the cannon plug where the wiring connects to the rest of the G1000 system.  But digging into all that wiring in the panel to find a pesky ground problem could chew through a lot of labor hours, so that's why we thought changing the probe could be a less expensive first step.

Except at $800, I'm not sure that logic still holds.  We could take the probe out and test in hot water, but again, the problem is intermittent so we could leave it there for days and it may or may not show back up.  That's why if there is a less expensive probe available this at least allows me to try something in the plane to see if the problem goes away.

I appreciate everyone's thoughts!

Jeff

[A64Pilot]

Very often finding the source of the overpriced gizmo is the trick, then buy the much lower priced identical item, like the defrost blower motor that was in another thread or the $ 500 or whatever it was gear switch that can be bought without the plastic wheel for $25, or the $800 or whatever it was landing gear solenoids that are actually $15 or so golf cart solenoids.

It’s very unlikely that temp sending unit was built only for a G1000 equipped Mooney, possible but unlikely. Trick is of course finding the source of supply.

You should be able to connect a multimeter to it while it’s connected to the G1000, fly and when the signal drops out, check to see if the multimeter shows any change.

I hope of course it’s not the Garmin

[carusoam]

Good news Jeff….

Sort of…

I had the OilT sensor of the O1 fail due to age….

Its thermistor stops behaving properly and fails slowly towards cold temps, and oddly takes hours and days to become useless….

 

The O1’s thermistor is also shared with many M20Js….

There are a few sitting on shelves in hangars owned by M20Js with JPI 900s in them….

 

The big problem… availability of the O1’s thermistor was terrible back in the pre-pandemic days…

 

Soooo… briefly…

Your failure sounds more like a wire connection problem than a thermistor wearing out…

Hopefully, finding a loose connection gets you back on your way quickly…

Since it’s G1000 related…

You may want to post a pic and a part number…

Finding a temporary solution might help with the problem solving…

I may have posted pics and part numbers of mine a few years ago… since I got help with a replacement from an awesome MSer…   

 

PP thoughts only, not a mechanic…

Best regards,

-a-

[MarkD34M]

Jeff:

I have an Ovation 1 and my recollection is, the probe goes into the oil cooler on the IO550. If you have the same set up and can confirm the part number I can send you one to try before you buy a new one. I have a spare (ask me how I know - I did the same thing you did but mine was the gauge).  I believe Mooney part number is 102-000606.  PM me if you'd like me to send it down.

Mark

[Jeff_S]

14 hours ago, A64Pilot said:

 

You should be able to connect a multimeter to it while it’s connected to the G1000, fly and when the signal drops out, check to see if the multimeter shows any change.

I hope of course it’s not the Garmin

@A64Pilot Thanks for this thought.  I'm trying to visualize how that would work. Where exactly would I connect a multimeter so that I could see it in-flight? The wires coming in through the firewall are all bundled together and go into one of the Garmin LRUs so I'm not sure how I would implement your idea. Can you help me understand this?

[skykrawler]

Somebody else probably knows more.....the Garmin architecture typically has the analog I/O connected to device/unit (GIA?) which performs the conversion and then a digital bus to the G1000 display unit.  So the poor connection, if that's the problem, is likely to this I/O device.   Your A&P should be looking at the wiring diagram.

You said:  I've had a flaky oil temp situation for some time now, where it will mysteriously drop out for awhile and then come back. 

but haven't qualified "for awhile" or when.  Only in flight? Also on ground? Engine running, not running.

[Jeff_S]

6 hours ago, skykrawler said:

You said:  I've had a flaky oil temp situation for some time now, where it will mysteriously drop out for awhile and then come back. 

but haven't qualified "for awhile" or when.  Only in flight? Also on ground? Engine running, not running.

It started this Spring and is totally unpredictable.  Sometimes it doesn't happen at all. Sometimes it shows up on the ground even before starting up, other times not until I'm in flight. It always has seemed to come back on, eventually, but it's something I need to get fixed.

[Jeff_S]

I hesitate to post this because...you know...karma.  But it appears (he says knocking on his skull, the closest thing to wood in the immediate vicinity) that the oil temperature dropout situation has been resolved.  I put the plane in with the avionics shop and they reseated the GEA 71 engine interface that all the probes go to. Ran through a full suite of diagnostics with Garmin, and came back with the expected NTF (no trouble found).

Except that I suspect simply re-seating the GEA 71 was the answer.  I live on the Atlantic coast, and corrosion creeps up in all sorts of places. Since that maintenance, the oil temp has behaved perfectly (oh shoot, there I go...don't jinx it!) so I'm keeping my fingers crossed. I just wanted to add to this thread in case people find it in the future with a similar problem.  Hopefully I will not have any reason to revisit this thread again!

[buddy]

Jeff what avionics shop did you use? I’ve also got the G1000 in my M20R and used Premier down at FXE the last time I had a problem and found them to be very knowledgeable.

[MatthiasArnold]

Besides re-seating the GEA also additional re-seating of the (big) firewall-through AMP style connectors could help in such situations.. I did both to resolve similar problems in the past. 
Not an avionics engineer, just an ordinary electronics & software engineer ;-)
Best, Matthias 

 

[Fly Boomer]

2 hours ago, MatthiasArnold said:

Not an avionics engineer, just an ordinary electronics & software engineer ;-)

Do you use DC-4 or DeoxIT or similar?

[A64Pilot]

On 11/20/2022 at 8:58 AM, Jeff_S said:

@A64Pilot Thanks for this thought.  I'm trying to visualize how that would work. Where exactly would I connect a multimeter so that I could see it in-flight? The wires coming in through the firewall are all bundled together and go into one of the Garmin LRUs so I'm not sure how I would implement your idea. Can you help me understand this?

Sorry just saw this, but I’m sure that if a wire doesn’t connect directly to the thermistor itself there will be a plug connection very close to it to facilitate its replacement.

If a wire connected directly to the thermistor I’d probably just put an alligator clip on the terminal and of course run the wire through the firewall and connect to the multimeter.

If there is a plug then of course there are ways to “break” into the plug, sometimes it’s as simple as sticking a needle into the backside of the plug, remember this is temporary and doesn’t need to be airworthy, just have to make sure it can’t cause a problem.

Find an electrician and or avionics person and ask their advice, often us A&P’s aren’t real knowledgeable with electrics

[Will.iam]

4 hours ago, A64Pilot said:

Sorry just saw this, but I’m sure that if a wire doesn’t connect directly to the thermistor itself there will be a plug connection very close to it to facilitate its replacement.

If a wire connected directly to the thermistor I’d probably just put an alligator clip on the terminal and of course run the wire through the firewall and connect to the multimeter.

If there is a plug then of course there are ways to “break” into the plug, sometimes it’s as simple as sticking a needle into the backside of the plug, remember this is temporary and doesn’t need to be airworthy, just have to make sure it can’t cause a problem.

Find an electrician and or avionics person and ask their advice, often us A&P’s aren’t real knowledgeable with electrics

This is the most versatile kick ass multimeter i have ever used. And i use it on all sorts of projects. I just wish i had it when i was going for my electrical engineering degree it would have been super convenient. The ability to track 2 different measurements and remotely can not be emphasized enough. It would be perfect for this situation as you could connect it inside the cowling and get the reading remotely in the cabin while flying. I just used it the other day as i was going to install an electrical outlet and wanted to make sure i had killed the power to the wires at the circuit breaker box. No problem just connect it to the wires and the go out in the garage with my phone and turn off breaker switches until i got the breaker that cut the power. By focusing the build quality on the high resolution ADC and not having to invest in a screen display or processors to display it because you use your own phone. You get a device that is much better in precision and acquisition with much more functionality then other models costing much more and usually more limited in functions. I highly recommend it. 

 

[EricJ]

5 minutes ago, Will.iam said:

This is the most versatile kick ass multimeter i have ever used. And i use it on all sorts of projects. I just wish i had it when i was going for my electrical engineering degree it would have been super convenient. The ability to track 2 different measurements and remotely can not be emphasized enough. It would be perfect for this situation as you could connect it inside the cowling and get the reading remotely in the cabin while flying. I just used it the other day as i was going to install an electrical outlet and wanted to make sure i had killed the power to the wires at the circuit breaker box. No problem just connect it to the wires and the go out in the garage with my phone and turn off breaker switches until i got the breaker that cut the power. By focusing the build quality on the high resolution ADC and not having to invest in a screen display or processors to display it because you use your own phone. You get a device that is much better in precision and acquisition with much more functionality then other models costing much more and usually more limited in functions. I highly recommend it. 

 

"Currently Unavailable"   

[Will.iam]

Oh i just remembered i used that multimeter when i was cleaning out my lift detector switch as i would listen to the beeps of continuity of the wires from the switch get more solid and clear as i sprayed derxit into the switch and work it back abd forth until i got a clean tone. I also used it on my sonar speaker replacements making sure they had good contact with the wires. 

[Will.iam]

7 minutes ago, EricJ said:

"Currently Unavailable"   

What the hell is this world coming to? I swear some big corp multimeter company like fluke must have bought them out as it is awesome and at a 10th the price of some of the simple oscilloscopes. All i can say is if you find one working on ebay, buy it!  

[EricJ]

58 minutes ago, Will.iam said:

What the hell is this world coming to? I swear some big corp multimeter company like fluke must have bought them out as it is awesome and at a 10th the price of some of the simple oscilloscopes. All i can say is if you find one working on ebay, buy it!  

Probably infringed on somebody's patent.

[Will.iam]

5 minutes ago, EricJ said:

Probably infringed on somebody's patent.

Actually i just deep dive into the site’s support chat and one partner left to finish his degree and the other co-founder kept running the business as a one man band. He finally got burned out in 2018 and has backed away from the project for a while. He did do a 1000 batch run in 2021 but everybody is back out of stock. He even admitted that he is a designer and engineer not a logistics and customer support personnel. So the more mature the mooshimeter becomes the more it doesn’t fit his skill set and needs the later skills type of guy to expand the product. Sounds a lot like mooney factory issues. How to increase scale big enough to lower manufacturing cost to turn a profit worth pursuing.  There are other wireless products on the market but they only goto 60v that not even good enough to test house hold voltage. And the competitors app on the phone is not as functional nor as smooth. He needs to offload the business to someone that does have the logistics and most importantly the money to get this into mass production instead of 1000 run batches. He is still active as the app gets updated when a new iphone or system software update comes out but has not made a comment on the support forum in over a year. 

[Will.iam]

BTW the UL testing they had to do to get this approved sounds like as big a pain the butt as getting an aircraft certified. Read their blog about the modifications they had to do to get this device to pass rf interference, lightning strikes, heat oven, high humidity electric zaps all because they wanted a 600v remote multimeter. Also had to encode a software sleep mode so customs wouldn’t flag it shipping to other countries as they don’t like boxes that try to pair to your bluetooth. 
https://moosh.im/category/announcements/

 

[EricJ]

9 hours ago, Will.iam said:

BTW the UL testing they had to do to get this approved sounds like as big a pain the butt as getting an aircraft certified. Read their blog about the modifications they had to do to get this device to pass rf interference, lightning strikes, heat oven, high humidity electric zaps all because they wanted a 600v remote multimeter. Also had to encode a software sleep mode so customs wouldn’t flag it shipping to other countries as they don’t like boxes that try to pair to your bluetooth. 
https://moosh.im/category/announcements/

 

At that stage they can always sell the product or business to somebody else rather than just let it die.    I always suspect there's more behind the story than usually told.

[MatthiasArnold]

On 5/23/2023 at 12:28 AM, Fly Boomer said:

Do you use DC-4 or DeoxIT or similar?

Being based in Germany, I usually utilize the products made by "Kontakt Chemie" (since decades).
They offer a comprehensive portfolio:

http://www.kontaktchemie.com/KOC/KOCproductsV2.csp