High oil temperature

[CPeterJr]

1963 C shows high oil temperature all year, but just a slim green glimmer between the needle and red line in summer. Cylinder temperature low green. Mixture 100° rich of peak. Opening cowl flaps lowers oil temperature slightly.Otherwise engine 1,850 hours on overhaul is excellent with fantastic oil analysis reports. Suggestions and/or comments, please.

[Andy95W]

First, you should really get a modern engine monitor that will give you an accurate reading.

In the meantime, make sure it stays in the green and don’t worry about it.  Everything sounds fine the way you described it.

[MikeOH]

Mine's the same way; right on the ragged edge in summer (230 per my Insight G3 engine monitor)

I've OHed the oil cooler, replaced the oil lines, vernatherm, baffles, you name it.  Great compressions, oil consumption ok (1 qt/8-10 hrs)

Bugs me still, but 5 years in and I'm just living with it.

[Utah20Gflyer]

I had an issue when I bought my plane of high oil temp readings.  A thorough cleaning of the harness/sensor connection resolved the issue.  A wire in poor condition losing continuity could also cause the same issue.  Something to check, although there are many other potential causes.  

[DCarlton]

39 minutes ago, MikeOH said:

Mine's the same way; right on the ragged edge in summer (230 per my Insight G3 engine monitor)

I've OHed the oil cooler, replaced the oil lines, vernatherm, baffles, you name it.  Great compressions, oil consumption ok (1 qt/8-10 hrs)

Bugs me still, but 5 years in and I'm just living with it.

I wrestled with similar issues for years trying all the same fixes with my mechanic.  Never really resolved it until I overhauled the engine.  Now all my temps are fine regardless of how I fly the airplane.  OT, OP, CHT, EGT all good.  Never identified root cause.  

[Prior owner]

Aero classics has a better oil cooler available for the C model. Installed in my plane it reduced oil temps year-round, but it was only a small reduction in temperature. 

[Mooney Dog]

Personally if its in the green then its good. In the summer itll be warmer and in the winter itll be colder. If oil pressure stays the same and other temps are good then it sounds all good to me.

[A64Pilot]

On 6/25/2022 at 1:36 AM, DCarlton said:

I wrestled with similar issues for years trying all the same fixes with my mechanic.  Never really resolved it until I overhauled the engine.  Now all my temps are fine regardless of how I fly the airplane.  OT, OP, CHT, EGT all good.  Never identified root cause.  

Most likely blow-by, blow-by is of course HOT

[Guest]

On 6/24/2022 at 5:43 PM, CPeterJr said:

1963 C shows high oil temperature all year, but just a slim green glimmer between the needle and red line in summer. Cylinder temperature low green. Mixture 100° rich of peak. Opening cowl flaps lowers oil temperature slightly.Otherwise engine 1,850 hours on overhaul is excellent with fantastic oil analysis reports. Suggestions and/or comments, please.

You could remove the temperature sensor from the engine and place it in a can of water, then heat it with a propane torch and see how it compares.  Boiling water should give you 212 ish degrees.  You could also place a thermometer in the water to add additional comparison points.

Old wiring and poor cone are a good possibility.
 

Clarence

[M20F]

I would echo with the older gauges it is hard to know what you really have.  Clarence’s suggestion is a good one you can try easily yourself.  Also ensure all the gaps around the cooler have RTV closing them off.  

That being said people get way too worked up as to where they are in the green.  Anywhere in the green is ok, that is why it is green. 

[Shadrach]

On 6/25/2022 at 12:50 AM, MikeOH said:

Mine's the same way; right on the ragged edge in summer (230 per my Insight G3 engine monitor)

I've OHed the oil cooler, replaced the oil lines, vernatherm, baffles, you name it.  Great compressions, oil consumption ok (1 qt/8-10 hrs)

Bugs me still, but 5 years in and I'm just living with it.

That is not an issue common to all F models.  My F runs 180-190° the summer maybe over 200° when it’s very hot or during a prolonged climb (OATs 80-100° ) and the cooler must be “winterized” in the cold months to ensure temperatures >150°. 

[Shadrach]

3 hours ago, M20F said:

 Also ensure all the gaps around the cooler have RTV closing them off.  

I have never seen an oil cooler that is sealed with RTV on a Mooney. Is this a common thing that I’ve just not seen? My cooler has 4 bolts go through the front cowl and hold it against the inside of the front lower cowling. Potential for leakage appears to be as close to nil as makes no differenc. 

[M20F]

13 minutes ago, Shadrach said:

I have never seen an oil cooler that is sealed with RTV on a Mooney. Is this a common thing that I’ve just not seen? My cooler has 4 bolts go through the front cowl and hold it against the inside of the front lower cowling. Potential for leakage appears to be as close to nil as makes no differenc. 

Mine has some gaps around the doghouse.  Not major but sealing them up made a huge difference.  I have the relocated cooler. 

[Shadrach]

19 minutes ago, M20F said:

Mine has some gaps around the doghouse.  Not major but sealing them up made a huge difference.  I have the relocated cooler. 

Interesting. Does your bird actually have a doghouse style cowl? My 67 does not but it came off the assembly line in July, perhaps early 67s were different. The baffle seals on my plane butt up to the top cowl piece. There is no separate plenum as there is on the earlier model years. I’m betting the OP does not have the rear mounted cooler.

[M20F]

5 hours ago, Shadrach said:

Interesting. Does your bird actually have a doghouse style cowl? My 67 does not but it came off the assembly line in July, perhaps early 67s were different. The baffle seals on my plane butt up to the top cowl piece. There is no separate plenum as there is on the earlier model years. I’m betting the OP does not have the rear mounted cooler.

Bad choice of words on my part.  I have a SWTA cowling due to RayJay.  Also bad on my part assuming a relocation.  For me though a little of the magic red dropped my oil temp by about 20 degrees.  The air was flowing but it was going through the baffling cracks and not the cooler.  

So I guess to restate look at the cooler and if you see any daylight around it squirt some RTV to block it.  

[Guest]

I use pieces of appropriate sized black foam weather stripping to seal the top and bottom face of the oil cooler to the mount on the cowl.  I can’t say if it helps or not, but I’ve seen this on lots of other pre J models.

Clarence

[Shadrach]

1 hour ago, M20Doc said:

I use pieces of appropriate sized black foam weather stripping to seal the top and bottom face of the oil cooler to the mount on the cowl.  I can’t say if it helps or not, but I’ve seen this on lots of other pre J models.

Clarence

The best minor mod I made to the oil cooler was fabricating nut plates for each side. Decreases reinstallation time to just a minute or two.

[47U]

On 6/24/2022 at 2:43 PM, CPeterJr said:

Suggestions and/or comments, please.

You didn’t say, but is there any chance you’re running chrome cylinders?

Otherwise, JohnZ and the Doc have good suggestions to verify the vernatherm and oil temp sensor.

Oh, and make sure your gauge cluster has a good ground, just because.

[MikeOH]

18 hours ago, 47U said:

You didn’t say, but is there any chance you’re running chrome cylinders?

Otherwise, JohnZ and the Doc have good suggestions to verify the vernatherm and oil temp sensor.

Oh, and make sure your gauge cluster has a good ground, just because.

@47U

Ok, I'll bite. What's up with chrome?

[Ragsf15e]

2 hours ago, MikeOH said:

@47U

Ok, I'll bite. What's up with chrome?

Theory is they have additional blowby which shows up as high oil use and warmer oil.  My oil temp is fine, usually 185, but I live somewhere cold and north of @M20Docapparently.

[47U]

2 hours ago, MikeOH said:

Ok, I'll bite. What's up with chrome?

Just my perception that chrome is less consistent to result in an acceptable break-in after overhaul, potentially resulting in more blow-by and higher oil temps/consumption.  

[MikeOH]

I seem to recall there's a color code for the cylinders as to type?  I can't remember which color chrome is.  Anyone? Bueller??

[47U]

14 minutes ago, MikeOH said:

I can't remember which color chrome is.

Chrome is orange.  

[Marauder]

I seem to recall there's a color code for the cylinders as to type?  I can't remember which color chrome is.  Anyone? Bueller??

Lycoming color codes:

Engine gray or unpainted – Standard steel cylinder barrels.
Orange stripe – Chrome-plated cylinder barrels.
Blue stripe – Nitride-hardened cylinder barrels.
Green stripe* – Steel cylinder 0.010 oversize.
Yellow stripe* – Steel cylinder 0.020 oversize.
​*Color code applicable only to engines overhauled in the field. Lycoming does not sell oversize cylinders.


Sent from my iPhone using Tapatalk Pro