231 oil temp/pressure issue at altitude

[jrwilson]

Hoping for some ideas on a cause.

m20k 231 w intercooler and Merlyn.  using 100w plus oil
 

On the way back from Washington, about 2 hours in at 12,000’ the oil temp started to creep up while the pressure dropped.  Topped out at about 190 degrees on jpi and pressure dropped to 31, top of yellow arc.  OAT was 8 to 10 deg F.  Had gone through some clouds for a bit prior to incident. Didn’t pick up any ice on wing.  Diverted to Medford.
 

during descent, about 10,000 feet and 20 deg F OAT pressure came back up and temps dropped back down.  CHTs we’re fine/TIT was fine.  Engine ran well.    On the ground there were no oil leaks on the plane and nothing dripping from turbo.  No apparent oil loss on dipstick.  Oil out the breather felt like water.  On the ground looked like water drops below breather.  Called mechanic he thought a temp probe froze causing possible vernatherm issue.

tried again, climbed to 12,000’, ran great, pressure 49 and temp 160 during climb.  Cylinders and TIT fine.  Went through a couple of clouds (no ice on wings) OAT was about 12 F.  Same thing started happening, temp going up and pressure down, still maybe 190 and top of yellow arc before I started doing something.  Descended through 9,000’ and 20f OAT and it remedied again.  Stayed low at 6,000 and finished flight.  Temps at 160 and oil pressure at 49-50 psi.  Cowl flaps closed.  
 

landed and still no leaks and no oil consumption.  Watery oil dripping from breather.
 

did the flight up to Washington two days earlier w no issues.  Flew higher at 16,000 to 21,000’ and OATs at 0 deg f.  It was cloudy but I dodged those because they were very convective and didn’t get into clouds until descent and below 10,000’

another possible factor was the day before I flew a very short hop from one island to the other for gas.  So not good for moisture in oil. Also it rained the night before.

any ideas would be appreciated!  Thanks.  

 

[jrwilson]

7 minutes ago, jrwilson said:

Hoping for some ideas on a cause.

m20k 231 w intercooler and Merlyn.  using 100w plus oil
 

On the way back from Washington, about 2 hours in at 12,000’ the oil temp started to creep up while the pressure dropped.  Topped out at about 190 degrees on jpi and pressure dropped to 31, top of yellow arc.  OAT was 8 to 10 deg F.  Had gone through some clouds for a bit prior to incident. Didn’t pick up any ice on wing.  Diverted to Medford.
 

during descent, about 10,000 feet and 20 deg F OAT pressure came back up and temps dropped back down.  CHTs we’re fine/TIT was fine.  Engine ran well.    On the ground there were no oil leaks on the plane and nothing dripping from turbo.  No apparent oil loss on dipstick.  Oil out the breather felt like water.  On the ground looked like water drops below breather.  Called mechanic he thought a temp probe froze causing possible vernatherm issue.

tried again, climbed to 12,000’, ran great, pressure 49 and temp 160 during climb.  Cylinders and TIT fine.  Went through a couple of clouds (no ice on wings) OAT was about 12 F.  Same thing started happening, temp going up and pressure down, still maybe 190 and top of yellow arc before I started doing something.  Descended through 9,000’ and 20f OAT and it remedied again.  Stayed low at 6,000 and finished flight.  Temps at 160 and oil pressure at 49-50 psi.  Cowl flaps closed.  
 

landed and still no leaks and no oil consumption.  Watery oil dripping from breather.
 

did the flight up to Washington two days earlier w no issues.  Flew higher at 16,000 to 21,000’ and OATs at 0 deg f.  It was cloudy but I dodged those because they were very convective and didn’t get into clouds until descent and below 10,000’

another possible factor was the day before I flew a very short hop from one island to the other for gas.  So not good for moisture in oil. Also it rained the night before.

any ideas would be appreciated!  Thanks.  

 

Watery oil out breather tube

[A64Pilot]

There is no probe on the vernatherm that will freeze so that’s not it. Could possibly be a bad vernatherm but I don’t think so, when they go, they aren’t usually intermittent, a bad vetnatherm usually shows up in the climb where oil temps are usually higher due to high power and lower than cruise air speeds, clogged oil coolers the same

What were your cylinder head temps during the high oil temps, and did they change any? Were they higher too? We’re you LOP or ROP and by how much?

Watery oil looks like a milkshake, cloudy, milky, sometimes yellowish, but not clear. What you have looks like good fresh clean oil, but then I’m on an Ipad 

Is it possible that you were running it very hard? 

Edited May 9, 2022 by A64Pilot

[jrwilson]

2 hours ago, A64Pilot said:

There is no probe on the vernatherm that will freeze so that’s not it. Could possibly be a bad vernatherm but I don’t think so, when they go, they aren’t usually intermittent, a bad vetnatherm usually shows up in the climb where oil temps are usually higher due to high power and lower than cruise air speeds, clogged oil coolers the same

What were your cylinder head temps during the high oil temps, and did they change any? Were they higher too? We’re you LOP or ROP and by how much?

Watery oil looks like a milkshake, cloudy, milky, sometimes yellowish, but not clear. What you have looks like good fresh clean oil, but then I’m on an Ipad 

Is it possible that you were running it very hard? 

Cht was 330 ish with no change during the issue.  Oil wasn’t milky on the dipstick either.  Looked clean.  I was rop by a little less than 100.

not running hard.  2450/26”

Edited May 9, 2022 by jrwilson

[A64Pilot]

I’m at a loss to explain it, did you just change oil? I ask as that pic looks like very fresh oil

Smell the oil, does it smell like fuel?

To be honest I’m reaching at straws here, and by posting that brings your post to the top of the list for more to see too, maybe someone else knows the answer. I’ve seen things like excessive blow by overheat oil etc, but I’ve not seen high oil temp come and go with altitude.

Initially I was thinking you were running the snot out of it, and the engine was running hot, but not with those cyl head temps.

[jrwilson]

1 hour ago, A64Pilot said:

I’m at a loss to explain it, did you just change oil? I ask as that pic looks like very fresh oil

Smell the oil, does it smell like fuel?

To be honest I’m reaching at straws here, and by posting that brings your post to the top of the list for more to see too, maybe someone else knows the answer. I’ve seen things like excessive blow by overheat oil etc, but I’ve not seen high oil temp come and go with altitude.

Initially I was thinking you were running the snot out of it, and the engine was running hot, but not with those cyl head temps.

Oil had about 16 hours on it at that point.  Smells fine.  
 

I appreciate the post bumps

[carusoam]

A graph is like a picture…

And a picture is worth….

 

Speaking of graphs…

Got a JPI full of data?

Download the data, send it to savvy, click the share button, post link here…

 

Much easier to discuss what we are seeing, than to try to memorize dozens of details to discuss….

Generally speaking…

1) Oil vented out the case vent will come with lots of condensed steam as well…

2) As OilT increases, OilP decreases… sort of a normal relationship…

3) Vernatherm issues can be easy to chase… pot of water and a thermometer… see what temp activates the vernatherm…

A few vernatherms have been replaced around here over the years…

4) Summary… your OilT was reporting 190°…  what is it usually reporting?

 

Could be a stuck vernatherm, allowing oil to flow through the oil cooler… resulting in a lower OilT than usual…

 

old PP thoughts only, not a mechanic…

Best regards,

-a-

[A64Pilot]

You know if oil,temp was only 190, and oil pressure was low, that’s not hot enough to make oil pressure dive.

Unless the cold oil relief valve was stuck open, just another guess. It’s purpose of course is to keep oil pressure from being too high with cold oil, it functions as relieving excess pressure by dumping it back into the pan, if it were stuck open it could result in low oil pressure at operating temps. It can stick partially of course

According to this the cold oil relief valve on a Continental is often in the filter, might change the filter and see, cheap, easy, can’t hurt.

https://tempestplus.com/wp-content/uploads/2019/01/Alaska-Cold-Starts-0613.pdf

Edited May 10, 2022 by A64Pilot

[Fly Boomer]

2 minutes ago, A64Pilot said:

cold oil relief valve

Where is this relief valve?

[A64Pilot]

Best to find out where it is in your engine. I don’t know, sorry.

The oil filter cold oil relief valve likely just bypasses the filter and really shouldn’t be your problem if I understand the concept.

I think you need to take it to or call a good engine shop, I would be uncomfortable flying at near min oil pressure.

Sorry, I wish I could give you an answer, but I can’t. But it coming on suddenly makes me think it’s not wear, but more likely something stuck, but a good engine shop will know where to look.

Edited May 10, 2022 by A64Pilot