abnormal oil pressure

Aztec Driver

Aztec Driver

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Elizabethtown, PA
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Bryon
This is the first time I have ever seen this indication and wondered what might be going on.

I changed the oil and filters on both of my engines this evening. Everything went as it always does. all done and buttoned up, I run it up to check for leaks. I noticed when I ran the power up that the oil pressure goes higher than normal. At idle, it is where it normally is, just below the green zone. At nominal rpm (1000-1500) it is in the green and steady. More than 1700 it goes above the green normal zone. Above 2000 rpm it is nearly pegged at the red line. At full takeoff power it is pegged. Both engines are like this.

IO320
7 qts 20W50 Phillips XC
CH48110 filter

When done the runup and leak check, no leaks and it has around 6 qts in, which is normal.

My partner flew it earlier in the day and had no such indications.

Anyone have any ideas what may be causing the problem? I find it difficult to believe it could be a filter issue, or even an oil cooler plugged up, as either one should have only happened to one engine, not both at the same time.
 
Vernitherm stuck?
But why would it do that right after an oil change....?
 
Other than correct weight of oil (which you have listed), oil relief valve?
 
Aztec Driver said:
This is the first time I have ever seen this indication and wondered what might be going on.

I changed the oil and filters on both of my engines this evening. Everything went as it always does. all done and buttoned up, I run it up to check for leaks. I noticed when I ran the power up that the oil pressure goes higher than normal. At idle, it is where it normally is, just below the green zone. At nominal rpm (1000-1500) it is in the green and steady. More than 1700 it goes above the green normal zone. Above 2000 rpm it is nearly pegged at the red line. At full takeoff power it is pegged. Both engines are like this.

IO320
7 qts 20W50 Phillips XC
CH48110 filter

When done the runup and leak check, no leaks and it has around 6 qts in, which is normal.

My partner flew it earlier in the day and had no such indications.

Anyone have any ideas what may be causing the problem? I find it difficult to believe it could be a filter issue, or even an oil cooler plugged up, as either one should have only happened to one engine, not both at the same time.
Click to expand...

How long did you run it? Did this condition ever diminish?
 
Aztec Driver said:
Anyone have any ideas what may be causing the problem? I find it difficult to believe it could be a filter issue, or even an oil cooler plugged up, as either one should have only happened to one engine, not both at the same time.
Click to expand...

Place a direct reading gauge on each engine and see if it is engine or gauge system.

find what is common to both engines in this respect.

If you have one of the 2 into 1 gauges, you lost the ground.
 
Tom-D said:
Place a direct reading gauge on each engine and see if it is engine or gauge system.

find what is common to both engines in this respect.

If you have one of the 2 into 1 gauges, you lost the ground.
Click to expand...

2 separate gauges.
 
OK, went to the airport today and decided to give it an extended runup and check.

Same abnormal indications at first. As it warmed up, I noticed that it would go to a higher rpm before it went to redline. When I started, anything above 1600 would put it close to redline. As things warmed up, I could get it to 1800, then 2000, then 2200, and finally I could do a full static runup and it would be just under redline.

Took it up and ran it at normal cruise and the pressures were normal. Sounds like an oil viscosity issue, but I have never experienced it with this light a grade oil or temps at 80-90F before.

When I first got it, the previous owner had been always using straight 100W oil and said he did that for oil consumption. Since I always preheat in the winter, that was not an issue, so I kept that up. Last year, after replacing some prop seals and repairing a few other leaks, I switched to a lighter oil and my oil consumption has not been affected, and is actually better, I think.

It flew fine, so I guess it is OK, it just baffles me that I have not seen this before. I don't recall any of the other planes I fly ever doing that either.
 
Last edited:
Bearing started to spin blocking off oil port.... :D

I see it occasionally on a fresh oil change where I get high pressure for a bit until the first time it gets thoroughly warmed up. I don't know if it has something to do with humidity when bottled or what, but sometimes oil looks clearer coming out than others. I kinda assumed it was water vapor trapped inside.
 
Sounds fairly normal to me, but I don't have your experience with your engines and their trends.

However I take care of a few planes that will overpressure the oil when cold.
 
That is normal behavior for 100W oil... It is also normal for multiviscosity... I get 80-90 psi on a cold takeoff with 15W50...
That it happened on two engines simultaneously means it is not mechanical..

This is summer... That Phillips screwed up and filled the cans with 100W is possible... If so, 100W is great summer oil... Run it like you stole it... But, change the oil again when fall comes...

denny-o
 
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