High Oil Pressure Upon Start

Nikhiln25

Nikhiln25

Pre-Flight
Joined
Jan 16, 2024
Messages
95
Display Name
Display name:
nikhiln25
I have Cessna 182R I recently purchased. It has a O470U with about 80 hours since factory reman in 2022.

When I turn my engine on, the oil pressure reads high. Over time as the oil warms up the pressure does come down on the ground to the green arc. As I apply fully oil pressure for take off it does go a little high again. But as I out power to enter normal climb from max tax off climb it’s in the green arc.


I asked an A&P about this and he didn’t seem too concern, saying it’s because the oil isn’t warm.

Here is a picture of what it looks like at cold start.


So my question is this something to worry about or should I get it checked by someone else? I use Philips XC 20W50. The previous owner said he did not change the oil grade with the seasons
 

Attachments

  • IMG_2570.jpeg
    IMG_2570.jpeg
    2.1 MB · Views: 34
What’s the temp? Cold oil can and will create higher oil pressure until it warms up and thins out.
 
All oils are thicker when cold than they are when hot, even multi viscosity oils like 20W50. When the oil is cold and thick, the oil pressure is high. How high? Probably high enough to open the pressure regulator valve nearly all the way. As oil heats up it gets thinner and this reduces the pressure. The 20W number means the oil at 0 F degrees flows just like 20 weight oil at 0 F degrees. The 50 number means the oil flows like 50 weight oil at 200 F degrees, but 50 at 200 F is still thinner than 20 at 0 F.

The green band on the oil pressure gauge is the expected oil pressure when hot at all operating RPMs. Your engine still has relatively low hours and low wear. As wear occurs and the tight bearing clearances loosen up, the oil pressure will drop some.

The area where you want to be aware is how does the oil pressure read when the engine and oil are both hot, like on a go around or when doing touch and goes on a hot day. My bird has about 1000 hours on a 30 year old rebuild. When hot at taxi RPM it is just into the yellow band below the green. I usually see this after a flight while taxing back to the hangar. I have talked to my mechanic and we are not worried. You shouldn't be either.
 
William Pete Hodges said:
All oils are thicker when cold than they are when hot, even multi viscosity oils like 20W50. When the oil is cold and thick, the oil pressure is high. How high? Probably high enough to open the pressure regulator valve nearly all the way. As oil heats up it gets thinner and this reduces the pressure. The 20W number means the oil at 0 F degrees flows just like 20 weight oil at 0 F degrees. The 50 number means the oil flows like 50 weight oil at 200 F degrees, but 50 at 200 F is still thinner than 20 at 0 F.

The green band on the oil pressure gauge is the expected oil pressure when hot at all operating RPMs. Your engine still has relatively low hours and low wear. As wear occurs and the tight bearing clearances loosen up, the oil pressure will drop some.

The area where you want to be aware is how does the oil pressure read when the engine and oil are both hot, like on a go around or when doing touch and goes on a hot day. My bird has about 1000 hours on a 30 year old rebuild. When hot at taxi RPM it is just into the yellow band below the green. I usually see this after a flight while taxing back to the hangar. I have talked to my mechanic and we are not worried. You shouldn't be either.
Click to expand...
Helpful thank you
 
Nikhiln25 said:
So my question is this something to worry about or should I get it checked by someone else?
Click to expand...
As with any indicators, perhaps verify the accuracy of your oil pressure gauge first. Has it ever exceeded the 100 psi redline? What's the reading at idle with warm oil?

In general, the only time you want to see the pressure outside the green is during initial run with cold oil not to exceed 100 psi and at idle/taxi above 10 psi.
 
If oil does not run off the stick then do not start your engine.

Overnight temps are often more significant than current OAT.

Cylinders and often components are lubed by “ splash n spray” and

the cold lard doesn’t do that.
 
Magman said:
If oil does not run off the stick then do not start your engine.

Overnight temps are often more significant than current OAT.

Cylinders and often components are lubed by “ splash n spray” and

the cold lard doesn’t do that.
Click to expand...
That’s a good rule of thumb thanks
 
Bell206 said:
As with any indicators, perhaps verify the accuracy of your oil pressure gauge first. Has it ever exceeded the 100 psi redline? What's the reading at idle with warm oil?

In general, the only time you want to see the pressure outside the green is during initial run with cold oil not to exceed 100 psi and at idle/taxi above 10 psi.
Click to expand...
No it has never approached 100 psi. I checked during taxi at 900 rpm after a flight today and it was solidly in the green (see pic
 

Attachments

  • IMG_2573.jpeg
    IMG_2573.jpeg
    2.1 MB · Views: 8
Klaus M said:
There's a Continental Operator's Manual X30097 available:

Loading…

continental.gilmoreglobal.com

In the mean time, I found this third party posting of Continental SIL 03-1 COLD WEATHER OPERATION – ENGINE PREHEATING:


Here's some more Continental Aerospace Technologies publications:

Loading…

continental.gilmoreglobal.com

Continental Aerospace Technologies

continental.aero continental.aero
Click to expand...
Thank you for sharing these
 
Nikhiln25 said:
No it has never approached 100 psi. I checked during taxi at 900 rpm after a flight today and it was solidly in the green (see pic
Click to expand...
I'd have your mechanic check the gauge accuracy just to see where's its at. Other than that all seems to be within the OEM guidance per your discriptions.
 
From the picture, it looks like the pressure is over the green, but less than red line. So that is fine.
 
Pinecone said:
From the picture, it looks like the pressure is over the green, but less than red line. So that is fine.
Click to expand...
Yes it’s in between. It never reaches the red line but runs higher than green arc
 
Will you have a winterization kit installed?

Some folks block off part of the oil cooler too.
 
Iv
Magman said:
Will you have a winterization kit installed?

Some folks block off part of the oil cooler too.
Click to expand...
I’ve never really considered a winterization kit.. I’ve actually never heard of it (first year(month) owner). What condition would it recommend in?
 
The kits vary with models.

Most block off the oil cooler duct.

Some restrict inlet cooling air.

Still others have insulating covers for the oil sump and intake pipes.

150’s and Conti 172’s have an option to use both mufflers to provide

Cabin Heat.

The Parts Manual is your friend.

I’m not sure where you are located or temps you deal with.
 
On many if not most aircraft, check POH, the green arc is the cruise oil pressure. So if start-up is above the green arc but below the redline and it decays to in-the-green-arc in flight, it may be fine. But checking with your mechanic is always a good idea if in doubt.
 
Magman said:
The kits vary with models.

Most block off the oil cooler duct.

Some restrict inlet cooling air.

Still others have insulating covers for the oil sump and intake pipes.

150’s and Conti 172’s have an option to use both mufflers to provide

Cabin Heat.

The Parts Manual is your friend.

I’m not sure where you are located or temps you deal with.
Click to expand...
Will learn more about this thank you. I’m in NY/NJ

Right now the lows in the night are mid 30s to 40. It will go to teens lows in January with occasionally single digit lows handful of days

I fly 1-2x a week. It will probably be 1x a week when it gets cold. My engine does have a pre heater installed
 
My 182R always behaves like that. Completely normal.
 
Where in NY/NJ are you based? Since you wrote both, presume it's downstate/tri-state area.

While it gets more than cold enough there to preheat, which is strongly recommended, temps at which a winterization kit is needed may not be that common some winters. Depending on the year and the cowl, many big-bore Continentals used by Cessna had some manner of winterization plates available. Sometimes they are still available, sometime you can talk to engineering and get the print to make your own. But usually the plates come into play around below 20 F OAT, and even that I've found is generous (too warm) for some.

If by not changing grade you mean running 20W50 all year around, that is not uncommon.

Preheat below about 40 F and certainly below 32 F. Personally prefer the cylinder base band + sump heaters (Reiff). Plug it in the night before. Invest in a fitted cowl blanket to keep the engine warm while you have your $200 hamburger on a nice sunny 5 F day. If you are on a ramp and pre-heating, recommend the cowl blanket and prop blade covers. In a hangar usually just plugging it in works fine.
 
If you end up looking into heaters, here’s one way:

www.pilotsofamerica.com

Cheap Heater

Being upset that I have not flown due to the lame excuse of cold wx, and Being too cheap and lazy to do an oil-pan and/or cylinder head heating solution, and Having a few moments of boredom and some stuff laying around, I made this abomination: I had the ceramic heater, some scrap sheet...
www.pilotsofamerica.com www.pilotsofamerica.com

I got tired of going to the airport the night before a flight to turn the heater on, and going back out to shut it down if I cancelled, so I bought a Switcheon. I turn it on and off from my bed…

I also put a heater in the cabin. I turn off the engine heater and turn on the cabin heater about 1 hour before flight time. Cabin heat makes the gyros happy.
 
3393RP said:
That's ~40 he posted, not -40.
Click to expand...
Time for my 40 below story.

I was in Norway in Feb '94 training with their army. One night we were sleeping in a snow cave and I went out to take a leak. Someone said it was minus 40. Fahrenheit or Celsius, I asked. Both!!
 
Last edited:
455 Bravo Uniform said:
If you end up looking into heaters, here’s one way:

www.pilotsofamerica.com

Cheap Heater

Being upset that I have not flown due to the lame excuse of cold wx, and Being too cheap and lazy to do an oil-pan and/or cylinder head heating solution, and Having a few moments of boredom and some stuff laying around, I made this abomination: I had the ceramic heater, some scrap sheet...
www.pilotsofamerica.com www.pilotsofamerica.com

I got tired of going to the airport the night before a flight to turn the heater on, and going back out to shut it down if I cancelled, so I bought a Switcheon. I turn it on and off from my bed…

I also put a heater in the cabin. I turn off the engine heater and turn on the cabin heater about 1 hour before flight time. Cabin heat makes the gyros happy.
Click to expand...
Get the Reiff or the Tanis. There is no such thing as cheap in aviation. Electric heaters with taped on ducts do not seem like a good idea to me. The goal is to heat slowly and evenly. Forty years of cold weather flying.
 
455 Bravo Uniform said:
If you end up looking into heaters, here’s one way:

www.pilotsofamerica.com

Cheap Heater

Being upset that I have not flown due to the lame excuse of cold wx, and Being too cheap and lazy to do an oil-pan and/or cylinder head heating solution, and Having a few moments of boredom and some stuff laying around, I made this abomination: I had the ceramic heater, some scrap sheet...
www.pilotsofamerica.com www.pilotsofamerica.com

I got tired of going to the airport the night before a flight to turn the heater on, and going back out to shut it down if I cancelled, so I bought a Switcheon. I turn it on and off from my bed…

I also put a heater in the cabin. I turn off the engine heater and turn on the cabin heater about 1 hour before flight time. Cabin heat makes the gyros happy.
Click to expand...
I just bought the Switcheon.. looking forward to use that since my airport is 50 minutes away.

What do you use for cabin?
 
Steamflyer said:
Where in NY/NJ are you based? Since you wrote both, presume it's downstate/tri-state area.

While it gets more than cold enough there to preheat, which is strongly recommended, temps at which a winterization kit is needed may not be that common some winters. Depending on the year and the cowl, many big-bore Continentals used by Cessna had some manner of winterization plates available. Sometimes they are still available, sometime you can talk to engineering and get the print to make your own. But usually the plates come into play around below 20 F OAT, and even that I've found is generous (too warm) for some.

If by not changing grade you mean running 20W50 all year around, that is not uncommon.

Preheat below about 40 F and certainly below 32 F. Personally prefer the cylinder base band + sump heaters (Reiff). Plug it in the night before. Invest in a fitted cowl blanket to keep the engine warm while you have your $200 hamburger on a nice sunny 5 F day. If you are on a ramp and pre-heating, recommend the cowl blanket and prop blade covers. In a hangar usually just plugging it in works fine.
Click to expand...
Thanks - I fly out of Blairstown 1N7. It does get into the teens/single digits for handful days of the year but it’s more like 20s.. I have a engine mounter heater for which I just bought the switcheon… I have it in a hangar that is not heated but so far I have not been using plugs or blanket but will look into that
 
High end of green arc is 60, so it’s running at about 70. I’ve read continental publications saying it shouldn’t be higher than 60 at full power
 
Nikhiln25 said:
I just bought the Switcheon.. looking forward to use that since my airport is 50 minutes away.

What do you use for cabin?
Click to expand...

Smaller space heater, on the pilot side floor, back, airflow pointed towards the front.
 
Steamflyer said:
Get the Reiff or the Tanis. There is no such thing as cheap in aviation. Electric heaters with taped on ducts do not seem like a good idea to me. The goal is to heat slowly and evenly. Forty years of cold weather flying.
Click to expand...

You have way more winter flying experience than me. However, consider that the rate of cooling by hot air as a medium is less severe than that from a heating band on metal, which are BOTH WAY LESS even than the first minutes of startup and combustion. I don’t think it makes any difference at all.

The engine never gets above 100 deg F; just warm enough like a nice day outside. My hot-air (pun) is distributed evenly to oil-pan, cylinders, oil cooler, fuel pump, vac pump, prop gov, starter, etc.

I’ve had 7-8 years since then to use something on the market, but have found no need. I roll my own, brew my own, etc ;)
 
Nikhiln25 said:
High end of green arc is 60, so it’s running at about 70. I’ve read continental publications saying it shouldn’t be higher than 60 at full power
Click to expand...
Continentals also have a minimum oil temp limitation. Don’t take off until oil temp is above 70°. That usually takes care of the pressure concerns. By the way, cold oil makes oil pressure sluggish to register and slow to react to RPM changes but I’ve never seen high pressure. Lycomings are different. No temp restrictions and they do build high pressures with cold oil.

I follow engine manufacturer recommendations for preheat. Continental says 20°F for a cold soaked engine. Lycoming says 10° but they start better with heat below 20°. The only winter prep I do is tape my oil cooler. I cover approx 3/4 of the cooler for winter and 1/4 for summer, but Alaska summers are pretty cool.
 
Stewartb said:
Continentals also have a minimum oil temp limitation. Don’t take off until oil temp is above 70°. That usually takes care of the pressure concerns. By the way, cold oil makes oil pressure sluggish to register and slow to react to RPM changes but I’ve never seen high pressure. Lycomings are different. No temp restrictions and they do build high pressures with cold oil.

I follow engine manufacturer recommendations for preheat. Continental says 20°F for a cold soaked engine. Lycoming says 10° but they start better with heat below 20°. The only winter prep I do is tape my oil cooler. I cover approx 3/4 of the cooler for winter and 1/4 for summer, but Alaska summers are pretty cool.
Click to expand...
What do you mean tape your oil cooler?
 
Aluminum duct tape across the front face of the oil cooler in order to maintain acceptable oil temps in cold air. I’ll look for a picture to post.
 
Some OLD Conti Oil coolers allowed the oil to congeal in very cold temps.

The oil temp would go sky high if you didn’t tape the cooler off.

Newer types are “ non- congealing “.
 
You must log in or register to reply here.
Back
Top