High oil temp when climbing

[Prior owner]

3 hours ago, M20Doc said:

The hose radius for the oil cooler transfer hoses and the remote oil filter look tight.  

Have you calibrated your factory oil temp gage by dropping the thermocouple in boiling water?

Clarence

Yes, I checked it with a handheld thermocouple unit in boiling water last year when I had it out to make a new pigtail with new pins. The factory  cluster gauge was within a couple of degrees of the thermocouple. Also swapped another cluster gauge in, and it was reading the same. 
 

I’m going to take another look at all the other oil hoses next week as well.

Edited July 13, 2020 by PilotCoyote

[Prior owner]

3 hours ago, Ross Taylor said:

Hey @PilotCoyote - I don't know if this helps, but I have the Eaton Aeroquip 666/667 teflon hose chart and bend radius info handy (from a recent fuel flow transducer installation)...if this happens to be the hose you've got?

Yes, I’ve got the same hoses. The 4.62 inside bend RADIUS would give me a hose wrapped around a 9.24 Diameter.....which I do not have.
 

I Would like to see how others have routed their oil cooler hoses!

Edited July 13, 2020 by PilotCoyote

[Prior owner]

I think these hoses were ordered up with a fairly bad guess as to length and fitting arrangements... I’m thinking that the installer wanted to make sure that the left magneto would be accessible and removable without disconnecting the oil hoses (which it is).

It sure would be helpful to see other M20C hose installations.

[47U]

My ‘63 had provision for the routing of the hoses over the top of the left bank of cylinders, perhaps yours were made to that length?  See the two holes that are plugged in my baffling, just forward of #2 cylinder?  That’s the #2 rocker box oil drain line B-nut, for perspective.  I was doing some baffling repair at the time.  There was a service bulletin (M20-110) to move the routing to under the cylinders. 

Then again, you have the remote oil filter above the copilot footwell.  Does that change everything?

tom 

[Prior owner]

It is possible that my hoses went over the top in the past and that might explain why they are so long.  I was the first person to remove the oil cooler hoses after they were installed during the engine overhaul, and they are in the same position now as when I found them. I’ll have to check my baffling to see if I have those two large holes. 
 

[Edit] whoops I meant to say: The remote oil filter housing does change things- both filter hoses screw into the vernatherm/temp probe housing..but it doesn’t affect the oil cooler hoses.

Edited July 13, 2020 by PilotCoyote

[Prior owner]

Had a very interesting discussion with Aero Classics Oil Coolers tech rep....

Mooney M20C’s either came with the Harrison or the Stewart Warner oil cooler (that much I knew).

The Harrison has poor heat rejection compared to the Stewart Warner, so if your aircraft has the SW cooler, it will run cooler.

The Aero Classics oil cooler that is typically specified as a replacement at most aircraft parts suppliers is PN 8000075. This is a 7 row cooler. This is the one that I have. It is better than the Harrison, but my understanding is that it is not as good as the SW cooler.

Aero Classics also has another cooler that is certified for the M20C that is a 6 row cooler with a taller fin design. It has the exact same physical dimensions. It has 30% greater heat rejection than the oil cooler model that I have. It is also about twice the price. He said that these coolers do a great job of cooling the oil in the M20C’s.
 

I removed my oil cooler, soaked it in Marvel Mystery oil overnight, flushed it, cleaned it in an ultrasonic cleaner with stoddard solvent, ran shop air through it, checked the air flow rate and solvent rate through it, and it seems completely unobstructed...however, these oil coolers are designed very simply- the oil does not zig-zag through the cooler, it simply flows from one side to the other taking the path of least resistance. It might be very difficult to tell if one of the oil rows was blocked...  but in my limited experience, it seems to be flowing just fine.

I don’t know what I’m going to do at this point. Going to check the hoses again. New hoses and upgraded cooler will run me $1200 +. 
 

So, what cooler do you have installed in your C/D? Does it run hot or not? From what I gleamed talking to the rep, the SW oil cooler does a pretty good job cooling the oil in the M20C. Perhaps those of us with the SW cooler aren’t having oil temp issues? 
 

 

Edited July 14, 2020 by PilotCoyote

[brndiar]

 My 43 years old & new oil cooler.

P.s. even with old one I did not have a high oil temp. Issue. 

(1977 M20C).

Lg, m

Edited July 15, 2020 by brndiar

[47U]

I’ve got the Harrison cooler, installed in 2004 along with new hoses.  (Looks like I’m probably due for hoses.)  No cooling issues.  This is 20” / 2400 rpm, 85 OAT.  About 1200 hrs SMOH w/ new Lyc cylinders.  Even climbing to altitude on a hot day, I don’t seem to have oil temp issues.  Guess I’m a lucky one.  Brainstorming here... could there be an issue with the remote oil filter?  

tom

 

[Andy95W]

1 hour ago, 47U said:

  Brainstorming here... could there be an issue with the remote oil filter?  

 

Doubtful, I think.  I have the same remote filter and my oil temp (on a JPI engine monitor) runs 180-190°, and even on a hot day only about 195°.

[Prior owner]

1 hour ago, 47U said:

 Brainstorming here... could there be an issue with the remote oil filter?  

tom

 

Well, the fact that you have the Harrison cooler pretty much blows my "inefficient oil cooler theory" right out of the water...!

I am going to have to look at everything, including the remote oil filter installation.

[Guest]

9 hours ago, PilotCoyote said:

Well, the fact that you have the Harrison cooler pretty much blows my "inefficient oil cooler theory" right out of the water...!

I am going to have to look at everything, including the remote oil filter installation.

I was discussing your issue with my local engine guy, and we questioned the flow/connections to your oil cooler.  Do you have the hose from the engine nearest the oil filter going into the bottom of the cooler and the return from the top of the cooler going into the left most fitting on the accessory cover.  

Reversed flow would reduce cooler efficiency.

This picture might help.

Clarence

 

Edited July 16, 2020 by M20Doc

[carusoam]

Hmmmm

is there a pictorial explanation for the flow in our oil coolers?

I can imagine plumbing improperly can be an easy mistake....

It may be possible to be stuck with air bubbles occupying some volume of the cooler making cooling and flow challenges...

Best regards,

-a-

[Guest]

51 minutes ago, carusoam said:

Hmmmm

is there a pictorial explanation for the flow in our oil coolers?

I can imagine plumbing improperly can be an easy mistake....

It may be possible to be stuck with air bubbles occupying some volume of the cooler making cooling and flow challenges...

Best regards,

-a-

This might help explain the connections.  The oil coolers mounted in the cowl are somewhat vertical, oil should enter the lower cooler fitting and exit the upper fitting.

Clarence

Edited July 16, 2020 by M20Doc

[Prior owner]

5 hours ago, M20Doc said:

I was discussing your issue with my local engine guy, and we questioned the flow/connections to your oil cooler.  Do you have the hose from the engine nearest the oil filter going into the bottom of the cooler and the return from the top of the cooler going into the left most fitting on the accessory cover.  

Reversed flow would reduce cooler efficiency.

This picture might help.

Clarence

 

Well Doc, thank you. Now I have a completely new set of questions....

Below is a pic of my oil cooler hoses, as they were installed when I bought the plane ( I have not changed the routing). I highlighted the connections for clarity (sorry, I wish I had a better picture of the accessory housing handy).

The red hose with the 90 degree fitting goes to the bottom of the cooler.
The green hose goes to the top of the cooler.

In the Lycoming Operators Manual I found what is supposed to be an accessory housing for my engine, an O-360 A2D... but my housing doesn’t look like that. I found a pic of a housing that looks like mine in an old Lycoming Overhaul Manual. I highlighted that picture to  match the highlighting of the picture I took of my accessory housing & hose arrangement.

Is something wrong here? Both of my cooler hoses are attached to the TOP of the accessory housing.... isn’t the oil flowing from the engine to the cooler supposed to be connected to the fitting below the oil screen housing, the return to the top of the accessory housing (below my remote oil filter housing)??

 

[Prior owner]

Oh man, it looks as though things are really messed up..

[47U]

You beat me to it...

 

[Prior owner]

7 minutes ago, 47U said:

You beat me to it...

 

No wonder the vernatherm pressure valve is open all the time- the oil cooler circuit is obstructed by a plug! Amazing that the cooler has been circulating oil and getting hot! 
 

Nothing is attached where I circled in blue..I hope M20doc can confirm this...

Edited July 16, 2020 by PilotCoyote

[47U]

So, the remote oil filter connections are mixed up with the oil cooler connections, improperly?  

[Prior owner]

9 minutes ago, 47U said:

So, the remote oil filter connections are mixed up with the oil cooler connections, improperly?  

No, the remote oil filter connections come from the airwolf vernatherm housing that is supplied with the Remote oil filter STC kit. They are correctly attached to the oil filter hoses. There must be a plug screwed into the accessory housing below the airwolf housing where the Outlet to the oil cooler is. So, I guess that the vernatherm stays pushed open Due to the blockage and oil is diverted to the cooler with the crazy arrangement that I have.... 

Edited July 16, 2020 by PilotCoyote

[47U]

So, you need to swap the plug for a hose and put the plug where the hose was, and that’s it?

[Prior owner]

Just now, 47U said:

So, you need to swap the plug for a hose and put the plug where the hose was, and that’s it?

I believe so....but I don’t think the plug at the top is an NPT, So I’ll need a different plug. This is crazy..!

[47U]

PROGRESS!

[takair]

I think you are plumbed per one of the optional configurations that is Shown in Figure 7-3, referenced in the figure that doc posted. The operators guide has that shown with variations that are acceptable. 

[Guest]

Looking at your picture above and your confirmation of the routing at the cooler, I have to agree with Rob that the outlet from the engine to the cooler is using the upper alternate fitting.

I would remove this hose and the fitting to verify that they are unrestricted.  If they are clear, connect your pressure pot to the line and force oil to the cooler and verify that it flows to your line marked in green.

Clarence

[Prior owner]

4 hours ago, takair said:

I think you are plumbed per one of the optional configurations that is Shown in Figure 7-3, referenced in the figure that doc posted. The operators guide has that shown with variations that are acceptable. 

Well dang....and there I was thinking we found the problem... thanks for that important bit of info.