Low Oil Temperatures in Mooney Ovation

[THill182]

I have a 2000 Ovation, with the O3 upgrade (310hp).

 

After my last engine overhaul, my engine runs very cool. Typically, in the winter I now put aluminum tape over the oil cooler to maintain >170F oil temps in cruise (LOP operations). But here is my question: Last week I flew all the way from the Canadian border down to Oklahoma. Starting in Montana, the temps were near-freezing at 9k ft with oil temps as low as 165F in cruise. When I got to Oklahoma, the temps at 11k ft were 18C, with oil temps at 198F.

 

So which is worse, cold oil or warn/hot oil? If I were to "winterize" my oil cooler I would run at 210-230F on climb-out when it is hot (to get 185F when it is cold).

 

Does anyone else have this problem with Ovations?

 

Thanks! TOM

[carusoam]

Welcome aboard, Tom.

Best regards,

-a-

[ArtVandelay]

I thought they had a thermostat (vernatherm) on the oil line to prevent this? If yes, then you need to replace, or if no you need to add one. Double check the sensor, does it read the ambient air temp before engine start?

[Guest]

The oil vernatherm valve is located below the oil cooler, typically they are set 175 degrees. I would suggest remove the oil temperature bulb, also by the oil cooler and boiling it in water to confirm its reading correctly. If it reads correctly I would replace the vernatherm valve.

Clarence

[THill182]

Thanks for the advice; really appreciate it. It was my understanding that this valve was properly set when the engine was overhauled and a new oil cooler was installed. I recall that the oil temperature gage was calibrated and also, I know that it reads the ambient temperature when the engine is cold. However, I have had a lot of engine issues for a while (oil leaks, eventually traced to a missing seal), and it is possible that something broke or wasn't properly reinstalled.

 

So I will have that checked next. Thanks! TOM

[ArtVandelay]

A lot of engine issues?!? Who did your overhaul, I like to avoid them.

[Cruiser]

Straight weight Aeroshell W100 or W65

Multi wt. Aeroshell 15W50

Multi wt. Phillips X/C 20w50

Oil pressure is 67 psi under power

 

All run about 189 in cruise summer and winter. If it gets really cold, it will drop to 171 - 172.  I will see 210 - 220 on the ground in extended taxi or idling for a long time. 

[THill182]

That is interesting, and very different from what I see. My temps are almost directly correlated with ambient temps. So that means I have a problem with said valve.

 

I run 100 Aeroshell all year (preheat in winter).

 

There is a longer story around the engine overhaul, but either way I think it is all resolved now (engine running well). Except this problem, of course, which I now will investigate...

 

Thanks! TOM

[Cruiser]

Let me revise some numbers. I went back and looked at a couple of flights I made to Florida last summer. Departed FXE at near 100°F ground temp. Engine oil temp was 197 and then dropped to 194 for the remainder of the flight. Several summer flights were in the 194°F range.

[THill182]

The oil vernatherm valve is located below the oil cooler, typically they are set 175 degrees. I would suggest remove the oil temperature bulb, also by the oil cooler and boiling it in water to confirm its reading correctly. If it reads correctly I would replace the vernatherm valve.

Just to follow up; did all that and replaced the vernatherm valve just in case -- no effect. Still running too cool (at 10,000 ft and 6C ambient, running 65% LOP, I got 167F -- below the 170F yellow arc). I think the engine just runs cold.

 

Anyway, I will "winterize" as I have done before to manage.

[BillC]

THill,

  I too have an Ovation and I concur with Cruiser. My temps are in the mid 190's. I fly to Florida from the Northeast and back every season at 8-9000'. 

  Years ago I bought a long probe thermometer to troubleshoot any potential gauge or vernatherm problem. I forget where I bought it but remember it was around $30.00 USD. I've used it countless times to help friends troubleshoot or verify oil temps.

Good luck,

BillC

[Guest]

Just to follow up; did all that and replaced the vernatherm valve just in case -- no effect. Still running too cool (at 10,000 ft and 6C ambient, running 65% LOP, I got 167F -- below the 170F yellow arc). I think the engine just runs cold.

 

Anyway, I will "winterize" as I have done before to manage.

does your oil cooler have the provision for putting a metal plate in front of the cooler?  Some do, some don't 

Clarence

[THill182]

does your oil cooler have the provision for putting a metal plate in front of the cooler?  Some do, some don't 

Clarence

No, I don't have the winterization kit. That is another thing I will look into. By the way, I know that the oil temps are correctly measured (had that checked), so I just have to find another way to keep the engine warm.

 

[carusoam]

Ovations have a winterization kit.  

I believe it is a piece of sheet metal that covers a known portion of the oil cooler.

contact Lasar, the favorite MSC/parts supplier of the Mooney world...

if you go that route, share some pictures.  I haven't seen one.

we have some Canadian Os that may be using that system or device.

best regards,

-a-

[jetdriven]

Some of the IO520 and IO550 Bonanza guys tape off the entire oil cooler in the winter to keep oil temps high enough. I'm not advocating that because every situation and engine model is different, but it does show how cool these things run in winter. 

[BillC]

Anthony,

  Here is a photo of the winterization plate for the Ovation. It slides in front of the oil cooler. I've never used it since I avoid the cold weather like the plague.

[Shadrach]

I prefer aluminum tape as it is not an all or nothing situation like some "winterization kits". Even with the OAT in the mid 60's, the oil barely touches 170df without blocking part of the cooler.

[carusoam]

Great picture, Bill!

My home drome has a month of temps that go below 30°F.

A week of temps below 20°F.

best regards,

-a-

[aaronk25]

I wouldn't worry about it. If it was at 140 that's different. My J runs 165 in winter.

[THill182]

Thanks for this feedback! So as a practical matter, I am using aluminum tape which works great, and gives me the flexibility to control/tune the oil temps quite nicely (I have a lot of experience). Usually I "adjust" twice or thrice a year (summer, fall/early winter, deep winter); my target is to keep temps between 175F to 210F in cruise. On climb-out try to stay below 225F; normally, I never see temps greater than 210F even on climb-out in the middle of the summer in the Mid-West.