Cowl Flaps (J Model)

[Tim-37419]

I have been reading the thread in the short body section about cowl flaps. Open or closed, I only get a single digit change in oil temp. In the summer, it's literally a 2 to 3 degree change.

 

I'm doing an oil change tomorrow and will have the cowl off for the filter. Anything I should look for? Is this an oil cooler problem?

 

Thx!

[Ragsf15e]

24 minutes ago, Tim-37419 said:

I have been reading the thread in the short body section about cowl flaps. Open or closed, I only get a single digit change in oil temp. In the summer, it's literally a 2 to 3 degree change.

 

I'm doing an oil change tomorrow and will have the cowl off for the filter. Anything I should look for? Is this an oil cooler problem?

 

Thx!

I don’t see much change in oil temp either, but the cowl flaps are more for the cylinders.  They let more air across and down (at least that’s the theory).  Cooler cylinders does slightly cooler oil.  Generally you’ll only need cowl flaps open in climb where you’re running high power at lower speeds and your cylinders will have a tendency to get too hot without extra air.  People usually use 380-400 as the highest cylinder temps they accept in climb or cruise.

If you’re able to keep your cylinder temps below this, you’re in good shape.

Do you have temp monitoring on all 4 cylinders?

[Tim-37419]

I have a JPI 830 and no CHT or EGT issues, I can't remember ever seeing my CHT's even near 400, I've always been impressed with how cool they stay compared to my last plane. I'll play around with the cowl flaps in cruise and climb configurations to see what they do to CHT's next time I'm up, it will be a good exercise for me.

 

My oil temp always feels high and I somehow got it in my head that the cowl flaps would help bring them down. It could be that I simply have no reference. In the summer at 2350 or 2400 squared I'm seeing oil temp between 220 and 225. Cowl flaps (even though I now know that's not their purpose) seem to get me down to 218 at best. The previous owner (or the mechanic) had redlined the oil temp on the JPI much lower than the factory gauge so this all could be psychological on my part.

[ArtVandelay]

I don’t think I have ever seen oil temp in the 200s on my 78J.

[N201MKTurbo]

My oil temps will get that high in climb in the summer. After I level off they go down to 190 or so. This time of year they rarely go above 210 in climb and go to 180 in cruise.

If your oil temps are that high in cruise, there is something wrong. Check the usual suspects. Flush the oil cooler, test the Vernatherm and inspect its valve seat.

[Ragsf15e]

41 minutes ago, ArtVandelay said:

I don’t think I have ever seen oil temp in the 200s on my 78J.

Yeah my oil temp sits around 185, so 200s seems high.  Here are some thoughts..,

I have seen it 210ish before during climb on a really hot day (like 100f + oat) when my chts were also 390ish.

You could have an oil cooler issue.  Any idea when it was last cleaned out or overhauled?

Could also be a vernatherm issue which isn’t too hard to check (although I haven’t done it).

Do you have the metal “heat shield” over top the oil cooler?  How are the air vanes on the cooler looking?

[N201MKTurbo]

2 minutes ago, Ragsf15e said:

I have seen it 210ish before during climb on a really hot day (like 100f + oat) when my chts were also 390ish.

Around here we put on a sweater when it gets that cold...

[A64Pilot]

Low 200’s is high for a J, but no where near concerning, actually from the oils perspective low 200’s is pretty much ideal temps.

[PT20J]

The EDM 830 is not primary, so the factory gauge and sender remain in place. This means that the JPI sender has to be located somewhere else. The usual installation is at the front of the engine by removing a pipe plug from an oil gallery. This point is farther from the oil cooler and hotter than the factory location at the rear of the engine. 

Cowl flaps don’t have much effect on oil temperature on my M20J.

 

[0TreeLemur]

3 hours ago, Tim-37419 said:

I have been reading the thread in the short body section about cowl flaps. Open or closed, I only get a single digit change in oil temp. In the summer, it's literally a 2 to 3 degree change.

 

Oil temperature is controlled by the Vernatherm.   Cowl flaps have no control over oil temperature unless mostly closed.

[Ragsf15e]

3 hours ago, Tim-37419 said:

I have a JPI 830 and no CHT or EGT issues, I can't remember ever seeing my CHT's even near 400, I've always been impressed with how cool they stay compared to my last plane. I'll play around with the cowl flaps in cruise and climb configurations to see what they do to CHT's next time I'm up, it will be a good exercise for me.

 

My oil temp always feels high and I somehow got it in my head that the cowl flaps would help bring them down. It could be that I simply have no reference. In the summer at 2350 or 2400 squared I'm seeing oil temp between 220 and 225. Cowl flaps (even though I now know that's not their purpose) seem to get me down to 218 at best. The previous owner (or the mechanic) had redlined the oil temp on the JPI much lower than the factory gauge so this all could be psychological on my part.

Ahhh @PT20J has a great point there.  Where’s the oil temp sensor for the 830?  In the front?  Higher temperatures might be normal.  Is the primary factory gage solid in the green?

[Tim-37419]

Thank you all for the great advice.

 

YES, the factory gauge stays well in the green. 

[EricJ]

I get hot oil climbing out in the summer sometimes, and if the cowl flaps aren't open all the way it'll definitely help to open them.   Once or twice while at high altitude or climbing at high altitude if I get a hot oil warning, opening the cowl flaps halfway will generally fix it.

 

[Ragsf15e]

34 minutes ago, EricJ said:

I get hot oil climbing out in the summer sometimes, and if the cowl flaps aren't open all the way it'll definitely help to open them.   Once or twice while at high altitude or climbing at high altitude if I get a hot oil warning, opening the cowl flaps halfway will generally fix it.

 

 Does it go down soon after the chts also drop?  It’s sort of a chicken or egg thing, but my oil temp has only been warm with higher chts and it cools down quickly when I cool them.

[ArtVandelay]

Ahhh [mention=17346]PT20J[/mention] has a great point there.  Where’s the oil temp sensor for the 830?  In the front?  Higher temperatures might be normal.  Is the primary factory gage solid in the green?

Not that high, I look at my past logs before I upgraded to 900 from 830, it’s only maybe a 5-10° difference.

When I was looking, I noticed I’ve have seen 200-209° temps , when I had high CHTs(400°) during a climb during the summer.

[Joe Linnebur]

Dealing with a similar oil temp. In annual, we had the shop do a delta test (oil temp into cooler vs. exiting cooler) and subsequently changed vernatherm. Cowl flap adjustments didn’t really help either. I believe it helped, but we haven’t been able to fly it lately. 

[A64Pilot]

13 hours ago, Ragsf15e said:

 Does it go down soon after the chts also drop?  It’s sort of a chicken or egg thing, but my oil temp has only been warm with higher chts and it cools down quickly when I cool them.

Of course to a pretty significant extent the heads are also oil cooled, so high CHTs will add heat to the oil.

Also most likely if your high CHT’s your climbing, high RPM and the engine is making more heat due to high power and the airflow is lower due lower airspeed due to climbing, so more heat, less cooling air.

I can’t remember ever climbing with my cowl flaps anything but wide open, I even cruise climb, that is let airspeed build as high as it will until I only get 500 FPM, this keeps my CHT’s in the middle of the green, while top of the green is allowable, it’s my belief that middle of the green is best for longevity.

I do whatever is required cowl flap opening wise to stay in the middle of the green, I won’t run higher CHT’s chasing a kt or two myself.

I believe the J is likely overcooled oil temp wise which isn’t a bad thing, but I believe some of the earlier aircraft may have run higher oil temps and the J fixed that and in typical GA fashion whenever a fix occurs if anything the fix is more than the min necessary.

[Pinecone]

My JPI 830 reads lower than factory gauge.

[Ragsf15e]

2 hours ago, Pinecone said:

My JPI 830 reads lower than factory gauge.

You have a different engine though. Do you know where the sensor is?

[Tim-37419]

I did an oil change and ground run today. I will fly tomorrow and record some measurements.

 

I took some photo's of the oil cooler and vernatherm in case any of that is of interest. The oil cooler was manufactured in 2013 and it has another sticker that makes me think it's been serviced since. I'll dig in the logbooks later to see what I find there. 

 

I would have pulled the vernatherm but I couldn't find my stash of large copper washers. Will check the garage later.

 

[Tim-37419]

[N201MKTurbo]

That's  not your Vernatherm. that is the oil pressure regulator.

On the J the Vernatherm is right next to the oil filter.

[Tim-37419]

argh! 

back to the hanger (not today though)

[Tim-37419]

Log update -

 

Did not find any mention of oil cooler replacement. I stopped reading at year 2002.

 

I did find two vernathem replacements, one in 11/2010 and another in 7/2016.

 

Do they go bad that often? I'm wondering if there were replaced but not root cause and that the engine just runs this way. I'm 1650 SMOH on a Mattituck

[mooniac15u]

54 minutes ago, Tim-37419 said:

On the Aero Classics website it says that part number is for a piper. They have a different part number for the M20J.