High Oil Pressure Upon Start

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
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I ended up with 2 - $15 Revlon hair dryers and 2 packing blankets from Harbor Freight. I put a heater in each cowl flap of my Mooney and cover the cowl. It's not perfect but it works well and I'm ready to start in about 30-40 minutes. It works for me.
 
Nikhiln25 said:
What do you mean tape your oil cooler?
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Cessna 180. My standard winter tape coverage. There’s no threat if left on in spring temps, it won’t overheat. At least mine never has.

I’m not a fan of Cessna’s winter fronts. Those make CHTs too hot. I’ve never had CHTs run too cool even in below zero temps. Do pay attention to leaning authority in cold weather. If you can’t see >100° difference between full rich and lean while in normal cruise, you aren’t getting adequate fuel flow.

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Magman said:
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 “.
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Firewall-mounted oil coolers are famous for freezing pretty much solid in very low temps, and preheating the engine does little to fix that. Warming the entire compartment fixes it. At very low temps, especially with single-weight oils, the pressure can get so high that the cooler's thin aluminum oil channels swell and fail. That's because the engine's pressure relief valve is downstream of the cooler, and thick, stiff oil in the cooler will hold back the oil flow and let pressures get astronomic. Putting the relief valve upstream of the cooler would mean nothing at all reaches the moving parts; it would just pop open and stay that way, draining the oil back into the sump.

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The "oil cooler bypass valve" is the Vernatherm. It closes when the oil warms up and forces the oil through the cooler. The oil in the cooler had better be moveable.
 
Non-congealing coolers have a port that flows a small amount of oil to the cooler regardless of the oil temp valve’s position. Not very sophisticated but it helps a little. If you wonder if you have one? Congealing cooler bases are very thin. Non-concealing cooler bases are much thicker.
 
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Oil is in the sump or tank.

The sump is in the cowling.

The cowling is in the hangar.

These factors tend to insulate the oil from warming from the overnight

low when the OAT rises.


If you take an oxy-acetylene torch at 6000 ish degrees it still takes

a long time to heat 2 gallons of oil. The cold soaked Crank, Cam, Jugs

Gears etc will only increase the time to heat.


Don’t go by current OAT!
 
Magman said:
Oil is in the sump or tank.

The sump is in the cowling.

The cowling is in the hangar.

These factors tend to insulate the oil from warming from the overnight

low when the OAT rises.


If you take an oxy-acetylene torch at 6000 ish degrees it still takes

a long time to heat 2 gallons of oil. The cold soaked Crank, Cam, Jugs

Gears etc will only increase the time to heat.


Don’t go by current OAT!
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You are partially making a case for not hangaring my plane! Ha.. good point though
 
Here is a picture of my oil cooler.. I’m not sure which kind it is, and if I should be doing the taping/winterization kit thing. Can anyone tell base off this picture?

Also today I flew at noon with OAT of about 48. It was 40 earlier. I didn’t pre heat (still waiting for my switheon to arrive). I had the same thing today.. high pressure on start up and take off. However, on my second leg when the oil was considerably warmer I noticed during full power takeoff oil pressure was in the green. So very clearly has to do with oil temperature.
 

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Your temps are perfectly normal. No need to preheat until temps drop below 20 degrees F.
 
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Nikhiln25 said:
However, on my second leg when the oil was considerably warmer I noticed during full power takeoff oil pressure was in the green. So very clearly has to do with oil temperature.
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There are exceptions, Poor engine grounding, even a small fraction of an ohm, can cause overreading of electric oil pressure or temperature gauges. Right after startup, that alternator is busily recharging the battery, and if the alternator and/or engine grounding to the airframe is poor, the electricity finds other paths, among them via pressure or temp sensors, through the gauge and to the bus and battery to ground. That boosts the sensor current and makes the gauges read high.

If your gauge is mechanical, as many older systems are, this doesn't apply.
 
So another thing I noticed yesterday (OAT at 25-30f at airport).

My CHTs just wouldn’t rise that high (see pic of cruise) and my engine oil temp was the lower side of half the green arc. I’m guessing this has to do with how cold it was, but is that just a fact of winter flying or should they be higher even this time of year.

I lean the red knob until I see rpm’s drop then add a couple back. It’s an 0-470-U

This pic was at 4500 ft and OAT was -10C. The oil temp probably 140/150?
 

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Going back to your first post - with oil temperature not even registering, as shown, a pressure above the green cruise arc is allowable on start-up. As the oil warms, the pressure should settle into the green. On a very hot day it may even be in the lower part of the green.

As for the behavior now that the weather is colder, it can be hard to keep some engines warm in winter. Although it was -10C at altitude, that could have been the temperature on the ground, with -20 to -30C at altitude. So keeping the oil warm enough can get challenging with some installs. Obviously pre-heat is essential as well.

One poster showed how they tape of part of the oil cooler to increase the temp. Their aircraft also showed the rivnuts that allow the placement of the winterization kit. However, that kit will dramatically limit airflow and can't really be used until the temps are around 5-10 F or below, regardless of the placard (in ones instance that I know of, not necessarily applicable to your 1282) indicating an upper limit of 20 F - that can be way too hot for the Cessna blocking plates aka winterization kit. Hence their choice to tape off part of the cooler.

Your cooler is a standard large-bore front mounted big-bore Continental cooler (and your alternator is belt driven at the back of the engine). Suspect it's non-congealing, meaning that a small amount of engine oil is always circulating in the cooler even when the cooler is barely needed to prevent the oil inside the cooler from congealing. Some are congealing however, without the permanent slight flow of oil at all times. Whether to tape it off partially or get the winterization kit is going to be up to you and your mechanic and the conditions in which you fly.
 
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