High oil temp when climbing

[Prior owner]

I was going to reseal my oil cooler at the cowl, but now I am really curious as to whether a slightly tired vernatherm will make any difference at all....so, As much as I dislike removing and replacing the cowls on my plane, I am going to do this: I will only change out the vernatherm for a new one.  I’ll leave everything else untouched. Then I’m going to go fly the plane on a 90+F day and report back. 
 

Hopefully I’ll get the new vernatherm by Friday. A member suggested that I test it before I install it, as a comparison. So I’ll do that as well ( uncalibrated meat thermometer- the same thermometer that I used to test the old vernatherm).
 

I also think we should take a poll regarding how many of us running warmer oil temps also have chrome cylinders. I have read that this can contribute to higher oil temps due to increased blow-by. 

[takair]

31 minutes ago, PilotCoyote said:

I was going to reseal my oil cooler at the cowl, but now I am really curious as to whether a slightly tired vernatherm will make any difference at all....so, As much as I dislike removing and replacing the cowls on my plane, I am going to do this: I will only change out the vernatherm for a new one.  I’ll leave everything else untouched. Then I’m going to go fly the plane on a 90+F day and report back. 
 

Hopefully I’ll get the new vernatherm by Friday. A member suggested that I test it before I install it, as a comparison. So I’ll do that as well ( uncalibrated meat thermometer- the same thermometer that I used to test the old vernatherm).
 

I also think we should take a poll regarding how many of us running warmer oil temps also have chrome cylinders. I have read that this can contribute to higher oil temps due to increased blow-by. 

As far as sealing the cooler, you can try it temporarily without pulling the cowl or cooler and it can get you some data. I had CermiNil before and now nitride and oil temps run about the same. 180-190. Looking back to when I had the higher temps, I think it was a combination of things that got them lower, the last was a new cooler. I think I ended up with a Niagara. Will look up later. 

[Ragsf15e]

9 hours ago, PilotCoyote said:

I was going to reseal my oil cooler at the cowl, but now I am really curious as to whether a slightly tired vernatherm will make any difference at all....so, As much as I dislike removing and replacing the cowls on my plane, I am going to do this: I will only change out the vernatherm for a new one.  I’ll leave everything else untouched. Then I’m going to go fly the plane on a 90+F day and report back. 
 

Hopefully I’ll get the new vernatherm by Friday. A member suggested that I test it before I install it, as a comparison. So I’ll do that as well ( uncalibrated meat thermometer- the same thermometer that I used to test the old vernatherm).
 

I also think we should take a poll regarding how many of us running warmer oil temps also have chrome cylinders. I have read that this can contribute to higher oil temps due to increased blow-by. 

I also wonder about how many of us or the other io-360a1as in the “cohort” have the oil cooler relocated behind the engine?  Supposedly it cools better there because it gets more airflow and doesn’t get beat up by bugs and rocks.  I’d love to hear from someone who did the relocation.  STC is $550 from lasar.

For the record, I do have chrome cylinders with plenty of blowby and a standard, front oil cooler.  It works fine normally but I don’t usually fly in real warm weather.

[Ross Taylor]

@Ragsf15e I've got the higher-than-I'd-like (200-230) oil temps with the standard oil cooler location.  Does moving the oil cooler really help?

[Brian E.]

59 minutes ago, Ross Taylor said:

@Ragsf15e I've got the higher-than-I'd-like (200-230) oil temps with the standard oil cooler location.  Does moving the oil cooler really help?

Same question here on a C model.  Never had cooler serviced though--EDM alarms at 220....very annoying.

[Ragsf15e]

2 hours ago, Ross Taylor said:

@Ragsf15e I've got the higher-than-I'd-like (200-230) oil temps with the standard oil cooler location.  Does moving the oil cooler really help?

Well I’m not sure if it helps, but Lasar advertises the relocation STC as Improving air distribution...

“Oil Cooler Relocation (M20E – M20F, 1967 & later with open baffle)

No. 126

Speed Increase Parts Hardware & STC Labor Hours 1.0 mph $550 10+

Description Moves the oil cooler from the lower cowl to a position behind the #4 cylinder. Provides better air distribution for both the cylinders and the oil cooler, while streamlining the lower cowl. Fits 200hp models with open baffle system.”

https://lasar.com/mods

 

[Ross Taylor]

Thanks @Ragsf15e - I did look that up after your first mention of it...but I wasn't sure if it really helped in practice.  Regardless, I did just notice that it's only for '67 and later.  Ours is a '66.  And, by the way, what are open baffles?  We've got the enclosed doghouse, not the open-top (what's that properly called?) that I see on some old Mooneys.  I'm still learning...

BTW - I did have a new vernatherm installed, but that didn't seem to make a difference in our case.

[MATTS875]

On 5/18/2020 at 12:04 AM, Ragsf15e said:

Cruise is kind of a different animal.  Curious though... what is your oil pressure at takeoff and what does it do as oil temp rises up that high?

In climb, it’s common for people to see high oil temp by climbing at Vx or Vy for a long time, maybe running too lean in climb (thus hotter cht), etc.  in cruise, those usually aren’t issues.

Both cases need to make sure the reading is accurate which is why I asked about pressure.  Oil pressure is very sensitive to temp changes.  Very.  It will drop noticeably as temp rises.  On my JPI, I can start to see pressure drop a couple psi with ~10 degrees increase in Oil temp.

I’m all set now. I had a baffling issue as well as a new vernatherm installed. Oil temps are good

[Tcraft938]

On ‎5‎/‎19‎/‎2020 at 4:07 PM, Htmlkid said:

 

it’s a Mooney M20F and the data is from a JPI 730 temps get to 230 on extended climbs

First I'm not a Mooney expert or A&P.  What I am, is a 1 year owner of a C model an in the process of breaking in a overhauled to new specs engine and my A&P likes to include me in the work "you learn your airplane and keep me honest".  Based on the strong recommendation of Pen Yann Aero and my A&P I would recommend you shallow your climb to a cruise climb.  While higher oil temps are normal during break-in, getting too hot is really bad.  I was told, first 30 hours takeoff, clean up as soon as possible, climb at 85 mph to safe altitude (about 400'), lower nose to get the 105 mph Vy for another 1000' and then lower the nose and pitch to maintain a cruise climb of around 120 mph or more.  All of this was to be done at full power and full prop rpm, the engine likes that better and gets more cooling air.  Albeit I have a carb engine you have fuel injection.  When get to 120-125mph I find my rate of climb is very similar to holding 105mph.  The only thing I'm giving up is I'm going a little farther over the ground for every foot I climb.  I was also told to run it hard once in cruise, nothing less than 75% power until oil consumption stabilizes, "if you fly and weather permits, don't fly for less than an hour, set the power and go and for God Sake, NO touch and goes!!".Yesterday I took off on a 92 degree day 670' msl, climbed to 6,500' for cool smooth air.  Hottest cylinder (assuming accurate instruments) was 368 and oil temp was 194.  During cruise climb hottest cylinder 344 and oil stayed at 184.  If you're dialing back the power and prop while pitching for slower airspeed you're really diminishing cooling air to the oil cooler and cylinders, for a longer period of time and not good for engine break in (what I've been told/taught).  Are you still using mineral oil for your break-in?  None of what I said, is enough to "solve" your problem, but it can help a bit especially once you get things sorted out.  When we installed the engine he flushed the oil lines and cooler and some junk came out, not much.  His point was, "you paid big buck for a nice OH, do you want to potentially pump junk we don't know about through the new engine?"  Oregon Oil cooler had one on the shelf for $240 and we got new oil lines, the others were 23 years old and could squeeze them a bit.  The other consideration I just thought of, are you on the ground much with the engine running or long taxi?  I was also told to minimize that.  Being at a non-towered airport that's easy.  First several flights did much of the checklist items while taxi, runup at end of runway with exercise the prop the last item.  If it's good, full prop, release the brakes, full power and go.  I hope it all works out well for you.  I will be curious to read the result after the new cooler and hoses.  

[Brian E.]

On 7/6/2020 at 11:50 AM, Tcraft938 said:

  During cruise climb hottest cylinder 344 and oil stayed at 184. 

Those a great numbers--wish I could be so cool.  My C oil temp is nearly always ~220 except for the coolest New England days. Servicing the cooler and hoses this week...

[Prior owner]

Small update:

New Vernatherm arrived. I tested it against the old one...here are the numbers using my candy thermometer-

Expansion from room temp to 150 deg F.     Expansion from 150 - 185 degrees F

Old Vernatherm:          0.007“                           0.140”

New Vernatherm:        0.046”.                          0.250”

At the 150-185F expansion, the difference between them is 0.110”, which is Approximately the thickness of two dimes. 
 

I cannot accurately measure for comparison the length of the each valve from the gasket surface end to the tip of the valve that seats against the engine oil pressure orifice, as the new valve has a different taper ( I couldn’t tell exactly where the valve seats on the taper against the engine without coating it with blue dye and screwing it in- I’m not at the hangar). So, not very scientific or precise here, but interesting to note that the new valve does move sooner, and does move farther than the old valve. 
 

I would like to know the exact distance between the gasket surface of the engine and the oil galley orifice where the valve seats, and I would like to know the length of each valve from the gasket surface to the area of the taper where it seats. Then I’d like to know the seating pressure at various temps- that would give me some real data.... but I’m way too busy and short on time to work on that- I just want to go fly!

(The new vernatherm is the one on the left - the more silver one with the pinched nut)

One other thing- the old valve tip feels ratchety when pushing the spring down. The new valve tip moves very smoothly against the spring

Hopefully it will go in  Saturday, and we’ll see if it amounts to a hill of beans.

[carusoam]

Great details coyote!

You might find even more dimensions regarding your part number from the Vernatherm company...

They have an applications chart for things like this... it might be helpful...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Ragsf15e]

32 minutes ago, PilotCoyote said:

Small update:

New Vernatherm arrived. I tested it against the old one...here are the numbers using my candy thermometer-

Expansion from room temp to 150 deg F.     Expansion from 150 - 185 degrees F

Old Vernatherm:          0.007“                           0.140”

New Vernatherm:        0.046”.                          0.250”

At the 150-185F expansion, the difference between them is 0.110”, which is Approximately the thickness of two dimes. 
 

I cannot accurately measure for comparison the length of the each valve from the gasket surface end to the tip of the valve that seats against the engine oil pressure orifice, as the new valve has a different taper ( I couldn’t tell exactly where the valve seats on the taper against the engine without coating it with blue dye and screwing it in- I’m not at the hangar). So, not very scientific or precise here, but interesting to note that the new valve does move sooner, and does move farther than the old valve. 
 

I would like to know the exact distance between the gasket surface of the engine and the oil galley orifice where the valve seats, and I would like to know the length of each valve from the gasket surface to the area of the taper where it seats. Then I’d like to know the seating pressure at various temps- that would give me some real data.... but I’m way too busy and short on time to work on that- I just want to go fly!

(The new vernatherm is the one on the left - the more silver one with the pinched nut)

One other thing- the old valve tip feels ratchety when pushing the spring down. The new valve tip moves very smoothly against the spring

Hopefully it will go in  Saturday, and we’ll see if it amounts to a hill of beans.

How much did it set you back?

[Prior owner]

1 minute ago, Ragsf15e said:

How much did it set you back?

$340 + tax, shipping 

[Prior owner]

32 minutes ago, carusoam said:

Great details coyote!

You might find even more dimensions regarding your part number from the Vernatherm company...

They have an applications chart for things like this... it might be helpful...

PP thoughts only, not a mechanic...

Best regards,

-a-

It would have been an even more interesting science project if I had measured everything, but I just don’t have the time right now. I will check the vernatherm site though ( I searched for info on the valve for quite a while and came up with only Lycoming SB’s and a Service Letter.  Lycoming has all the drawings for them as well... they were quite helpful.
 

Researching it got me thinking about the pressure relief feature of the valve, and how you would never get an indication On the oil pressure gauge if the vernatherm had to open due to an oil cooler clogging, or due to the valve having weak spring seat pressure... you’d only see higher oil temps as a result. The vernatherm could be modulating all day due to pressure, and the oil press gauge would just remain stable.

[bonal]

On July 5, 2020 at 4:13 PM, Brian E. said:

Same question here on a C model.  Never had cooler serviced though--EDM alarms at 220....very annoying.

Unfortunately it's not an option for our C models because of Battery location.  I suppose you could move the battery but I don't think there is an STC for the cooler on a C

[bonal]

When I replaced the vernatherm we saw a 10 to 15 degree improvement on our C.

[Prior owner]

49 minutes ago, bonal said:

When I replaced the vernatherm we saw a 10 to 15 degree improvement on our C.

THAT would make me very happy!

[Prior owner]

I took my old vernatherm and made a tool out of it to lightly dress the seat in the accessory case.

I expanded the vernatherm with a heat gun, then placed 4 number 8 lock nuts under it To keep it from retracting all the way, then pro-sealed everything. The pressure on the nuts keeps the assembly extended and also provides enough friction so that the whole assembly rotates together.

 If I elect to use it, I’ll use valve lapping compound very sparingly and will of course have to be extremely careful and very thorough with the clean-up. Dressing the seat is accomplished by Twisting the vernatherm by hand back a forth using its threads as a bearing surface. One pic is of the seat in the accessory case.
 

Edited July 10, 2020 by PilotCoyote

[Prior owner]

I Installed the new vernatherm, and sealed around the oil cooler at the cowling with a nice custom silicone gasket. See pic No real difference in oil temps. 

I chose not to do anything to the tapered Vernatherm orifice in the accessory case, as it looked fine to me.

 Test flight showed only a very slight improvement In oil temp, if any.

The old vernatherm shows excessive and recent wear on the shaft where the poppet has been repeatedly compressed to its stop (Galling and polished there). See pic. This may indicate that there is a restriction in the oil cooler circuit that is causing the vernatherm poppet to compress the spring and partially bypass the oil cooler.

Oil temperature 10 minutes after leveling off at 5500 ft with 82F OAT was around 205-210F. See pic.  Oil temp during 115 KIAS climb was between 220-225F.

After taxi back hangar, oil temp gauge indicated 200F. Lasar thermometer indicated that oil temp probe housing was also 200F. Front face of oil cooler indicated 177F at the hottest spot. So, oil is getting to the cooler, but I can’t be sure how much...

I think I have a restriction, possibly a kinked hose. More exploration coming later this week. Oil cooler is an Aero Classics cooler with correct part number for the M20C, and the manufacture date aligns with the engine overhaul  about180 hrs ago.

Rather than send the cooler out for service, I’m going to remove the hoses and take a close look at them.

Edited July 12, 2020 by PilotCoyote

[ArtVandelay]

I’m not a mechanic, but if you took out a spark plug and pressurize the case with air, then disconnect the hose coming from the cooler, could you not check to see if oil is flowing freely. If it is, then continue disconnecting hoses looking for an obstruction?

[Prior owner]

6 hours ago, ArtVandelay said:

I’m not a mechanic, but if you took out a spark plug and pressurize the case with air, then disconnect the hose coming from the cooler, could you not check to see if oil is flowing freely. If it is, then continue disconnecting hoses looking for an obstruction?

I’ve got an oil pressure pot to use for testing ( pic below is when I used it after re-installing he oil lines and cooler last year for inspection). The aircraft has older Teflon Lined hoses that were removed for inspection last year. My thoughts are that one of them may have a slight kink where it bends between the engine and firewall, that occurred after re-installation of the hoses. Teflon lined hoses can get a “set” in them and moving them around can be a bad idea. Impossible to see a slight kink from the outside, especially with fire sleeves on the hoses.

The hoses are 12 years old but only have 180 hours on them. I elected to keep them after inspecting them, as they appeared to be airworthy, even after carefully running a borescope through each one. I’m going to just replace them. The pic below shows them in the plane after I made some notes on them, prior to removing them for inspection. The hose bend radius behind the engine is fine for the size hose that it is, but I think there is more going on in that bend than I can see just by looking at the outside of it. The photo has a bit of an optical illusion, because it actually looks like the hose is kinked on the outside, but that’s because part of the hose is sitting behind a bundle of wires. Wish I had a better pic of the hose bend, but it actually looks fine on the outside...

Edited July 12, 2020 by PilotCoyote

[mike20papa]

I'd be very suspect of that hose bend radius (both hoses). I bet you can go to the Parker web site and find out what the min. radius bend is, but common sense says ?!

[Ross Taylor]

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?

[Guest]

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