High Oil Temps - Where to Start

gwav8or · February 18

Went up today to fly for a bit. On takeoff, I noticed the oil temp was a tad high but it wasn't bad. Around 180 IIRC. Once I got to about 5500, I noticed the temp was at redline. I backed the MP/RPM back to 24/24 and kept it at full rich mixture. Cowl flaps remained open. The oil temp came down to about 240 but wouldn't go below that. Even backing MP down to 20" it stayed close to redline. Normally, I see temp around 160-170, don't remember it ever being over 180, especially in cruise.

Where do I start with troubleshooting?

**Ragsf15e** · February 18

1 hour ago, gwav8or said:

Went up today to fly for a bit. On takeoff, I noticed the oil temp was a tad high but it wasn't bad. Around 180 IIRC. Once I got to about 5500, I noticed the temp was at redline. I backed the MP/RPM back to 24/24 and kept it at full rich mixture. Cowl flaps remained open. The oil temp came down to about 240 but wouldn't go below that. Even backing MP down to 20" it stayed close to redline. Normally, I see temp around 160-170, don't remember it ever being over 180, especially in cruise.

Where do I start with troubleshooting?

Was your oil pressure different than it normally is?

gwav8or · February 19

Was your oil pressure different than it normally is?

Oil pressure was top of green arc on takeoff. By the time it got to altitude it had dropped to about 74. Which is about normal.

Oil temp was normal at run up, about 120.

CHT was normal as was EGT. I only have single probes for CHT/EGT though.

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**hammdo** · February 19

Grant just had a new panel installed, so that could have tweaked something….

-Don

M20F · February 19

If your oil pressure is normal but the temp is at levels you indicate would check the temp probe. Oil temp of 240 is going to degrade pressure.

**Ragsf15e** · February 19

57 minutes ago, gwav8or said:

Oil pressure was top of green arc on takeoff. By the time it got to altitude it had dropped to about 74. Which is about normal.

Oil temp was normal at run up, about 120.

CHT was normal as was EGT. I only have single probes for CHT/EGT though.

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As @hammdo said, temp that high should make a noticeable decrease in pressure. Id check the probe.

**cliffy** · February 19

Put the probe in boiling water and see what the temp shows.

Ground it with an alligator clip wire you make up.

Check it cold- check it hot using an IR temp gun.

**Shadrach** · February 19

Having just gone through an issue with faulty reading, I don’t think the thermocouple has failed, but worth checking. Problems can be caused by maintenance, but they are normally binary (it works or it doesn’t). I cannot envision a maintenance induced issue that causes it to read 60° high.
I would expect increased oil burn at those temps and a decrease in oil pressure. No chance that you winterized the cooler earlier in the season and then went flying on an unseasonably warm winter day?

gwav8or · February 19

Having just gone through an issue with faulty reading, I don’t think the thermocouple has failed, but worth checking. Problems can be caused by maintenance, but they are normally binary (it works or it doesn’t). I cannot envision a maintenance induced issue that causes it to read 60° high.
I would expect increased oil burn at those temps and a decrease in oil pressure. No chance that you winterized the cooler earlier in the season and then went flying on an unseasonably warm winter day?

Oil pressure may have been a couple psi lower but still within normal range for what I typically see. Oil pressure was about 74-75 and I typically see just below 80.

No winterization.

The oil temperature needle was kinda bouncing off redline, from about 230-250 from what I recall.

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gwav8or · February 19

Grant just had a new panel installed, so that could have tweaked something….
-Don

Yeah I’m gonna go check the oil temp probe and the connections to the indicator this afternoon.

I got a full panel done so I agree and think the most likely scenario would be the connection to the indicator since the whole cluster was removed and reinstalled.

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gwav8or · February 19

Went to the airport today and the oil temp was showing 150 after sitting for over 24 hours. Obviously oil temp wasn't that high in reality.

Tapped on the housing of the indicator (not on the glass) and the reading came down to about 80. Ambient temps today are around 60.

Should I send it off to have it overhauled or should I fly it and see what happens?

If send for overhaul, who should I send it too? Looks like Rudy's also overhauls Oil temp gauges, I'll give them a call but open to other recommendations.

Looks to me like the part number is 169C-910-11?? Looks like there is or used to be another digit/character to the left of the C maybe?

Edited February 19 by gwav8or

**Fly Boomer** · February 19

22 minutes ago, gwav8or said:

Looks to me like the part number is 169C-910-11?? Looks like there is or used to be another digit/character to the left of the C maybe?

A few years ago, another MooneySpacer was selling the following, so I suspect your number is correct:

CHT Cluster Gauge Garwin 169C-910-12
Oil Temp Cluster Gauge Garwin 169C-910-11
Oil Pressure Cluster Gauge Garwin 169C-914-1
Cluster Gauge Box Garwin 22-169
L & R Fuel Gauges Garwin 169C-910-28 1 and 2

**cliffy** · February 21

There is a place in Lock Have PA that also overhauls them In fact 2 places there.

You're lucky you have the six individual units Each ca be overhauled separately and not as a 6 pac for the early ones.

There is also replacement units new available from several suppliers

gwav8or · February 21

There is a place in Lock Have PA that also overhauls them In fact 2 places there.
You're lucky you have the six individual units Each ca be overhauled separately and not as a 6 pac for the early ones.
There is also replacement units new available from several suppliers

I looked around for replacement units but couldn’t find them. Can you share a source?

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**cliffy** · February 21

I think these are what I was thinking about

https://mitchellproducts.com/product/modular-gauges-fuel-quantity-gauges/

gwav8or · February 29

Well crapola as my dad used to say.

I sent my oil temp indicator to Rudy Aircraft Instruments and they called me Tuesday to let me know that it is too far gone and can't be overhauled.

So, I'm now earnestly searching for a replacement for a Garwin 169C-910-11.

I called Mitchell Products and the sales guy that I talked too and gave the above part number too gave me their part number that he said would replace my indicator. Unfortunately, he didn't seem to know what he was talking about. The Garwin gauges are modular and square and the replacement part number he gave me wasn't even close to being a replacement.

So if anybody has a Garwin 169C-910-11 laying around, let me know?

Jblanton · February 29

Might try Sigma Tek in Augusta, KS.

169CL Cluster Gauges (sigmatek.com)

**Shadrach** · February 29

There are three complete Garwin clusters of eBay right now. All sold as working when removed:

https://www.ebay.com/itm/256388531976?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=vPetlGimTdK&sssrc=2047675&ssuid=hlthMC2_SPa&widget_ver=artemis&media=COPY

https://www.ebay.com/itm/175867767018?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=rtQKZv-ZQei&sssrc=2047675&ssuid=hlthMC2_SPa&widget_ver=artemis&media=COPY

https://www.ebay.com/itm/186315130728?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=V0vyyRaQSM2&sssrc=2047675&ssuid=hlthMC2_SPa&widget_ver=artemis&media=COPY

you could keep the remaining as spares or try to sell them individually on eBay

JayMatt · February 29

https://www.instagram.com/p/CwQpsXPPsof/?img_index=1

Vernatherm

**Shadrach** · February 29

Also, @Alan Fox might have one.

gwav8or · February 29

1 hour ago, Shadrach said:

There are three complete Garwin clusters of eBay right now. All sold as working when removed:

https://www.ebay.com/itm/256388531976?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=vPetlGimTdK&sssrc=2047675&ssuid=hlthMC2_SPa&widget_ver=artemis&media=COPY

https://www.ebay.com/itm/175867767018?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=rtQKZv-ZQei&sssrc=2047675&ssuid=hlthMC2_SPa&widget_ver=artemis&media=COPY

https://www.ebay.com/itm/186315130728?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=V0vyyRaQSM2&sssrc=2047675&ssuid=hlthMC2_SPa&widget_ver=artemis&media=COPY

you could keep the remaining as spares or try to sell them individually on eBay

Yeah, those look to be the same as the one I have and I'll look into getting one of them. However, my concern is that the one I pulled out of my plane is a Garwin 169C-910-11 and all the ones I've seen at LASAR, BAS, salvage places, etc are Garwin 169D-910-11. I'm not sure of the difference between the "C" variant and the "D" variant and if there would be any compatibility issues. While I'd absolutely love to go ahead and put in the JPI 900 that I plan on doing later in the year, I just dropped $$ on a panel upgrade and I'm not sure if my CFO (wife, aka better 2/3) would be too positive toward spending the extra $$ right now lol.

**Rick Junkin** · February 29

26 minutes ago, gwav8or said:

I'm not sure of the difference between the "C" variant and the "D" variant and if there would be any compatibility issues.

I have one I pulled out of my '89 M20M last year. I'm headed out to the hangar in a bit and will look at the model number and let you know.

Cheers,
Junkman

gwav8or · February 29

7 minutes ago, Rick Junkin said:

I have one I pulled out of my '89 M20M last year. I'm headed out to the hangar in a bit and will look at the model number and let you know.

Cheers,
Junkmn

Awesome, thank you!

**Shadrach** · February 29

2 hours ago, gwav8or said:

Yeah, those look to be the same as the one I have and I'll look into getting one of them. However, my concern is that the one I pulled out of my plane is a Garwin 169C-910-11 and all the ones I've seen at LASAR, BAS, salvage places, etc are Garwin 169D-910-11. I'm not sure of the difference between the "C" variant and the "D" variant and if there would be any compatibility issues. While I'd absolutely love to go ahead and put in the JPI 900 that I plan on doing later in the year, I just dropped $$ on a panel upgrade and I'm not sure if my CFO (wife, aka better 2/3) would be too positive toward spending the extra $$ right now lol.

Yours looks like there is a D preceding the C.
Texas Air Salvage. They have several vintage Mooneys in their parts donar inventory.

1C4604CF-22CD-459D-B71D-AB7B553D56D0.jpeg.2c7a9f0fdf507e22d1e8698dc359705d.jpeg

**Rick Junkin** · February 29

1 hour ago, gwav8or said:

Awesome, thank you!

My bad, my removed gauges are the cluster type. I thought I might be able to remove the oil temp gauge from the cluster block but no luck so far.

Not so many cheers,
Junkman

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