Observed oil temp difference based on probe location

[shawnd]

Engine: Continental TSIO360MB

After my recent avionics upgrade, I switched from JPI 830 to Garmin's GEA 110 + GI 275 EIS. The JPI had its oil temperature probe was installed in a tapped hole in the front of the engine below the crank since it was non-primary (see sample reference picture from JPI). The Mooney OT cluster gauge was connected to a temperature probe at the oil cooler end plate based on TCM documentation. I assume this is the "factory location" and as a result Garmin's OT probe was also installed there.

 

With my JPI, I used to get "normal" engine readings of 180+ degrees. However, with the new setup, I am getting 135F on a cold day (OAT -2 C at altitude) at altitude, and around 165F today when ground temp was around 60F.  I am assuming there is a difference in measured temps due to location - front of the engine is the oil right after it passes by the cylinders whereas the measurement of oil by the cooler is much later and has allowed the oil to cool down as it travelled back. Questions:

1. Is this correct?
2. How much temperature difference is expected?
3. If (1) is true, is there a way to measure the hottest oil temperature to gauge the behavior of the engine correctly?

Thank you as always.

Shawn

[Ragsf15e]

2 minutes ago, shawnd said:

Engine: Continental TSIO360MB

After my recent avionics upgrade, I switched from JPI 830 to Garmin's GEA 110 + GI 275 EIS. The JPI had its oil temperature probe was installed in a tapped hole in the front of the engine below the crank since it was non-primary (see picture). The Mooney OT cluster gauge was connected to a temperature probe at the oil cooler end plate based on TCM documentation. I assume this is the "factory location" and as a result Garmin's OT probe was also installed there.

 

With my JPI, I used to get "normal" engine readings of 180+ degrees. However, with the new setup, I am getting 135F on a cold day (OAT -2 C at altitude) at altitude, and around 165F today when ground temp was around 60F.  I am assuming there is a difference in measured temps due to location - front of the engine is the oil right after it passes by the cylinders whereas the measurement of oil by the cooler is much later and has allowed the oil to cool down as it travelled back. Questions:

1. Is this correct?
2. How much temperature difference is expected?
3. If (1) is true, is there a way to measure the hottest oil temperature to gauge the behavior of the engine correctly?

Thank you as always.

Shawn

My plane also has a garmin eis but my oil temp probe is a jpi probe. It’s in the primary spot next to the oil cooler.  My plane is new to me, so I’ve still been getting use to it, but I haven’t seen the oil above 140 degrees yet, albeit in cold winter flying.  I wish I had an answer to your questions.  Im going to try covering some of the cooler and see if that changes my oil temp.

[Fix]

Following, since I have the same "problem" with my original gauge showing my ~140F on a hot day.
It's in for annual and I'll see if we can check the probe and take it from there.

[Will.iam]

13 hours ago, shawnd said:

Engine: Continental TSIO360MB

After my recent avionics upgrade, I switched from JPI 830 to Garmin's GEA 110 + GI 275 EIS. The JPI had its oil temperature probe was installed in a tapped hole in the front of the engine below the crank since it was non-primary (see picture). The Mooney OT cluster gauge was connected to a temperature probe at the oil cooler end plate based on TCM documentation. I assume this is the "factory location" and as a result Garmin's OT probe was also installed there.

 

With my JPI, I used to get "normal" engine readings of 180+ degrees. However, with the new setup, I am getting 135F on a cold day (OAT -2 C at altitude) at altitude, and around 165F today when ground temp was around 60F.  I am assuming there is a difference in measured temps due to location - front of the engine is the oil right after it passes by the cylinders whereas the measurement of oil by the cooler is much later and has allowed the oil to cool down as it travelled back. Questions:

1. Is this correct?
2. How much temperature difference is expected?
3. If (1) is true, is there a way to measure the hottest oil temperature to gauge the behavior of the engine correctly?

Thank you as always.

Shawn

I have tsio-360mb and that picture is not what my engine looks like.  Fyi

[shawnd]

Just now, Will.iam said:

I have tsio-360mb and that picture is not what my engine looks like.  Fyi

Yes - it's just to illustrate the location of the alternate probe location. Source:  pages 5-6 https://www.jpinstruments.com/wp-content/uploads/2012/10/INST-103-RevE-10-09-RPM-modified-.pdf

[M20F]

1 hour ago, Will.iam said:

I have tsio-360mb and that picture is not what my engine looks like.  Fyi

That is because that picture references every type of engine except a TSIO-360MB. 
 
I am a bit lost as to why this picture was chosen.  

[shawnd]

1 hour ago, M20F said:

I am a bit lost as to why this picture was chosen.  

It was a better source to reference given its JPI's own installation manual.  See my post above with the reference link. Main point that it drove was the different points in the engine where the JPI OT probe could be installed. I edited my original post to clarify this a bit.

[shawnd]

16 hours ago, Ragsf15e said:

My plane also has a garmin eis but my oil temp probe is a jpi probe. It’s in the primary spot next to the oil cooler.  My plane is new to me, so I’ve still been getting use to it, but I haven’t seen the oil above 140 degrees yet, albeit in cold winter flying.  I wish I had an answer to your questions.  Im going to try covering some of the cooler and see if that changes my oil temp.

 

2 hours ago, Fix said:

Following, since I have the same "problem" with my original gauge showing my ~140F on a hot day.
It's in for annual and I'll see if we can check the probe and take it from there.

This is good feedback @Ragsf15e and @Fix- this means I likely don't have to have the A&P folks dunk the probe in hot water and see if it's registering temperatures correctly. So most likely it's narrowing it down to location of the probe.

[Fix]

11 minutes ago, shawnd said:

This is good feedback @Ragsf15e and @Fix- this means I likely don't have to have the A&P folks dunk the probe in hot water and see if it's registering temperatures correctly. So most likely it's narrowing it down to location of the probe.

My idea is to remove probe at put it in water or heat it with something with reference termometer and see how my gauge reads.

 

 

[cbarry]

Prior to a panel upgrade, my Eagle had the Moritz gauges and a JPI 700.  I could expect to see about a 20 degree (F) inflight difference between the two oil temp probes’ readings.  I may be wrong, but this was one way to tell if the oil cooler was working well.  Now with just the JPI 900 using the probe location the JPI 700 did (the cooler side), I believe the  “working oil” to still be about 20 degrees warmer—all else being equal.

[pkellercfii]

I made the switch from a JPI EDM 800 to an EDM 900 for my TSIO-360-MB just over a year ago. With my case as well, that changed the location of the oil temp probe from the supplemental position in the crankcase nose to the engine type certificated location at the base of the oil cooler. I'd say that my average measured oil temps haven't changed much as a result of the probe location change, but I do see much faster variation in oil temperature from the new location. That observation is pretty much entirely the result of inspecting the logged engine data after flights. Your reported oil temp of around 160 F with OAT around 60 F sounds is very similar to what I'm seeing. On a recent flight from PGD to my home base of TTA, just after top of climb over S. Florida in January I was seeing an oil temp just over 160 F with the OAT at 50 F.  The OAT fell to around 15 F near the end of that flight, resulting in the oil temp dropping to around 140 F or less.

I can't provide any advice regarding the Garmin EIS. I've never dealt with any Garmin EIS. Keep in mind that the engine service manual specifies that the vernatherm is supposed to close completely at oil temps between 168 and 172 degrees F, so we really shouldn't be seeing oil temps very much higher than 170 F from certified primary oil temp instruments on TSIO-360-MBs. The highest oil temp I recall seeing from my EDM-900 was about 195 F, just after landing on a hot summer day.

--Paul Keller

 

[M20F]

5 hours ago, shawnd said:

It was a better source to reference given its JPI's own installation manual. 

I wouldn’t assume that to be right.  Call JPI or your installer.  A picture that isn’t your engine should not be your basis of reference.  
 
This is a @$50K question potentially, why take chances. 

[Z W]

I happened to be looking at my Savvy reports yesterday for the last 12 months. It says my oil temps are about average for M20Ks in their system at 163 dF. They definitely get a lot lower in the winter months. It has always given me the note that they "are not high enough to purge the engine of moisture." For whatever that's worth.

I believe my probe is at the base of the oil cooler. This is a TSIO-360-MB2B with a G500Txi EIS. I'll verify the probe location next time I have the cowl off.

[pkellercfii]

I used to get uptight about my TSIO-360 engine oil temps being too low at around 160-170 F. After hearing at an IA renewal seminar that peak oil temps will typically reach ~50 F above the supply temperature for NA engines and ~75 F above supply temp for turbos, I’m not concerned about 160-170 F oil supply temps anymore. In fact, that IA renewal seminar makes it sound like Continental’s vernatherm spec of 170 F for the TSIO-360-MB is about right.

—Paul Keller

 

[Marc_B]

19 hours ago, M20F said:

I am a bit lost as to why this picture was chosen.  

Continental Maintenance Manual shows picture for IO-550R and TSIO-550 oddly enough and doesn't show the TSIO-360 at all.  I don't find a picture or diagram for the TSIO-360 in the Mooney IPC, Service Manual, or TCM IPC.  Probably just the only picture included in the install manual.

 

@shawnd From MVP manual:  "Oil temperature can vary throughout an engine. Your engine’s oil temperature specifications are based on a specific location of the oil temperature probe. If the MVP is to be used as the primary oil temperature instrument, install the oil temperature probe (P-120) in the primary oil temperature pick up point for your engine."

I know that it's not the same engine monitor, but still...the basic gist is that the engine/aircraft manufacturer was using a specific location for measurement of oil temperature to use as the temp spec range.  So if you measured this in other locations it my not be the same.  Did you ever pay attention to the temp range on the primary analog dial previously and does it jive with your new data?

 

[M20F]

3 hours ago, Marc_B said:

Continental Maintenance Manual shows picture for IO-550R and TSIO-550 oddly enough and doesn't show the TSIO-360 at all.  I don't find a picture or diagram for the TSIO-360 in the Mooney IPC, Service Manual, or TCM IPC.  Probably just the only picture included in the install manual.

 

@shawnd From MVP manual:  "Oil temperature can vary throughout an engine. Your engine’s oil temperature specifications are based on a specific location of the oil temperature probe. If the MVP is to be used as the primary oil temperature instrument, install the oil temperature probe (P-120) in the primary oil temperature pick up point for your engine."

I know that it's not the same engine monitor, but still...the basic gist is that the engine/aircraft manufacturer was using a specific location for measurement of oil temperature to use as the temp spec range.  So if you measured this in other locations it my not be the same.  Did you ever pay attention to the temp range on the primary analog dial previously and does it jive with your new data?

 

My advice is call Maxwell he is an authorized EI dealer, installed mine and thousands of MVP-50’s, and Paul or somebody (maybe even Don) will tell you. 
 
Why guess this is an easy one. 

[Fix]

On 3/2/2025 at 7:26 PM, Fix said:

Following, since I have the same "problem" with my original gauge showing my ~140F on a hot day.
It's in for annual and I'll see if we can check the probe and take it from there.

At annual we found it's location well hidden on the oil cooler and not funny to remove just to check it.
Also the connection on top of the probe was loose, and surely why it's not working as it should or at least near end of it's life.
Didn't want to mess with it there since I didn't have a replacement.

Yesterday I finally changed my Oil temp probe, with correct tools, time and headache...

I did a quick ohm reading of the old and new probe.
Old probe was around 780ohm and new was 620ohm in ambient temperature.
Less ohm = higher reading on the gauge, so this appears to be correct.

Will test fly next couple of days to verify.

M20K 252 - TSIO 360 SB
Part: Rochester 3080-37 Oil Temp Probe 5/8-18 Nf3 100-250F


 

Cover sheet is removed...

Edited July 9 by Fix

[Ragsf15e]

4 hours ago, Fix said:

At annual we found it's location well hidden on the oil cooler and not funny to remove just to check it.
Also the connection on top of the probe was loose, and surely why it's not working as it should or at least near end of it's life.
Didn't want to mess with it there since I didn't have a replacement.

Yesterday I finally changed my Oil temp probe, with correct tools, time and headache...

I did a quick ohm reading of the old and new probe.
Old probe was around 780ohm and new was 620ohm in ambient temperature.
Less ohm = higher reading on the gauge, so this appears to be correct.

Will test fly next couple of days to verify.

M20K 252 - TSIO 360 SB
Part: Rochester 3080-37 Oil Temp Probe 5/8-18 Nf3 100-250F


 

 

I had similar low readings over the winter, but in the summer I am seeing 180 on the same probe. Yesterday I flew with takeoff temp at 93f and isa +18 up to 10,000’ and my temp was ~180-190 all the way up. Settled around 170 in cruise.  I think the oil cooler is very effective in cold temps.

(same engine as you)

[Fix]

2 hours ago, Ragsf15e said:

I had similar low readings over the winter, but in the summer I am seeing 180 on the same probe. Yesterday I flew with takeoff temp at 93f and isa +18 up to 10,000’ and my temp was ~180-190 all the way up. Settled around 170 in cruise.  I think the oil cooler is very effective in cold temps.

(same engine as you)

I had low reading all time.
I started to notice it this January when it was cold out side and the oil temp lower than I would expect.
And before cover the Oil Cooler I wanted to know if my oil temp was correct.

I assume that the needle should stand straight up when you have 180f.
Hope to test fly on Friday.