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Oil Pressure Low

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Phenomflyer237

Member
Hello all , we have an o-360 Carb engine, after an oil change with the builder shortly after purchasing the plane the oil pressure dropped. At start we have 42 use to hang right at the green at 55. Then in flight it drops to 35 and the temp stays steady at 180-190 range. Here is what i have done
we did go from a tempest to a champion filter
w100 plus oil
Verified indications are correct via manual gauge.
changed oil and cleaned suction screen no debris found
changed the new oil filter and checked it for debris none found
Oil pressure relief-changed to the white spring part # LW-11713 went from 5 washers behind standard to 4 washers behind the white
initial start up oil pressure was at 70PSI,
In flight when the plane warms up the pressure decreases to 35 and stays steady.

Any ideas are welcome thanks
 
Oil Pressure

Lycomings don't like low oil pressure. If the oil pressure in flight is actually 35 # you may have already damaged the engine. What is the history of the engine?
 
What indicator do you have? My AFS indicator started showing low so I took it to my mechanic who tested it manually and got a reading of 75. I have a new sender but it has been cold so it hasn't been installed yet.

I hope that it is something similar.

John
 
low psi

part # LW-11713 went from 5 washers behind standard to 4 washers behind the white

When you remove the washers your oil psi decreases. If you add a washer the psi will increase . You can add up to 9 washers (check this number to be sure)
each washer should raise your psi by 5 . Hope this helps Good luck
 
Low oil pressure can have two basic causes:

1 Low pump output. That could be from wear in the pump or from the pressure relief valve dumping output at too low a pressure. The stronger spring and more washers might help, but if pressure continues to drop when warm I'd suspect...

2 Pressure losses in the system. The usual one is when the bearing clearances become large and oil dumps out from around the bearings faster than the pump can keep up with. An internal leak such as missing plug in an oil galley is possible but is not as likely to happen suddenly.

How many hours on the overhaul? Got any paperwork on the overhaul? What does oil analysis show? Sudden drop after oil change. Gotta wonder what kind of oil/supplements were in there before.

Ed Holyoke
 
with the stiffer spring i reduced washers as it should take less initially.

I have good pressure at start up75 psi then it decreases reciprocal of oil temp rise. it stabilizes at 40psi.
It never rises with increase of RPM only ever goes down from the baseline engine start.
I am still suspicious of the oil pressure relief seat although it looks okay.
I think tomo I will try another washer or two just to see if it suddenly seats..

has anyone ever checked pressure on the oil cooler side(the pilot side of the accessory case)???
I found a plug there that i removed and fitted a second oil line and fitting to i am hoping to check differential pressure and see if the issue is in the oil cooler circuit. I guess the pump could be bad or losing pressure elsewhere.
 
a thick, straight weight oil like the 50 weight W100 is going to produce a lot more pressure when cold due to it's viscosity when cold. This is normal and expected. It's too thick for winter op's in my opinion (read the recommend temp ranges in the Operators manual). If you have properly confirmed the gauge, you have some work to do. I disagree with the other poster that this has damaged your engine. However, it does need to be addressed, lest you end up with no pressure in the air some day and get a forced landing with major engine damage.

Ed covered this pretty well. 1) failing pump 2) problems with pressure relief system bleeding off too much oil (debris in the seat is somewhat common and produces these symptoms) 3) excessive downstream leakage (bad bearings, leak, etc.) 4) pump inlet blockage .

Bypasses are in place to keep blocked coolers and filters from causing this problem.

The fact that it showed up- quickly points toward problems in the pressure relief or pump inlet blockage, though all are possible and in play. Lycoming pumps have had a history of self-destructing in the past though I think the current generation are fairly reliable.

EDIT: I would also ask the builder / previous owner if it always ran at 35 PSI warm, in cruise. If this is the case and the OP instrument has been properly verified, I would be looking closely for a manufacturer defect in the pressure relief assembly, as well as confirming that the correct bearings were installed in the engine during it's overhaul. For example, if the crank was ground M003 and STD bearings were used, you would see this type of problem. In theory, you would catch this when checking main bearing clearances, but I have a hunch that this check is not routinely on lycoming rebuilds, due to the difficulty in case splitting.

Larry
 
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Just some thoughts:
New-to-me plane so you don?t really know the history, did you change oil brands or type, do you know what is has been running?

With a clean filter and screens, I?d like to know more about how you verified the oil pressure gauge. These gauges and their sensors are far less reliable than the oil system.

Messing around with the pressure relief valve may mask a developing problem.

And finally does this plane have an inverted oil system?
Good luck
Tim Andres
 
Vernatherm

okay so today i ran 6 washers behind the white spring had oil pressure at 78PSI all the way through a run up. But at takeoff the pressure slowly started trickling down to about 37 PSI calling for a return to the runway. I am really starting to suspect a vernatherm issue. The pressure never rises after start only goes down with engine warm up. And it goes substantially down after takeoff, has anyone seen what a failed Vernatherm does?
Thanks
 
Phenomflyer237 said:
okay so today i ran 6 washers behind the white spring had oil pressure at 78PSI all the way through a run up. But at takeoff the pressure slowly started trickling down to about 37 PSI calling for a return to the runway. I am really starting to suspect a vernatherm issue. The pressure never rises after start only goes down with engine warm up. And it goes substantially down after takeoff, has anyone seen what a failed Vernatherm does?
Thanks
Click to expand...

Not that.

A vernatherm blocks an oil cooler bypass when the oil reaches (ballpark) 180F, forcing all flow to the cooler. A failed vernatherm simply allows oil to bypass the cooler, the result being warmer oil. If oil temperatures are normal, the vernatherm is not the source of a pressure problem.
 
Phenomflyer237 said:
okay so today i ran 6 washers behind the white spring had oil pressure at 78PSI all the way through a run up. But at takeoff the pressure slowly started trickling down to about 37 PSI calling for a return to the runway. I am really starting to suspect a vernatherm issue. The pressure never rises after start only goes down with engine warm up. And it goes substantially down after takeoff, has anyone seen what a failed Vernatherm does?
Thanks
Click to expand...

Did you by chance fly it when you verified with the mechanical gauge?
 
Step 1

Step 1 verify gauge is reading actual pressure during ALL phases of flight. Sticking a mechanical gauge on it for a few minutes tells you nothing.
Why did you change the pressure relief spring?
I don't think 35 psi "ruined your engine" as someone stated.
 
Oil Pressure

The oil pressure green arc on the 0 360 Lycoming in certified Pitts is 60-90 psi. If I saw 35 psi in flight I would reduce power to minimum required and head for the nearest airport while looking for emergency landing sites. I would not fly the airplane again until a detailed engine inspection had been performed. I find it absolutely appalling that anyone would defend flying a Lycoming powered airplane with 35# oil pressure.
 
jrs14855 said:
The oil pressure green arc on the 0 360 Lycoming in certified Pitts is 60-90 psi. If I saw 35 psi in flight I would reduce power to minimum required and head for the nearest airport while looking for emergency landing sites. I would not fly the airplane again until a detailed engine inspection had been performed. I find it absolutely appalling that anyone would defend flying a Lycoming powered airplane with 35# oil pressure.
Click to expand...

I would verify that the gauge is accurate before tearing down a engine.
 
Oil Pressure

Tommy123 said:
I would verify that the gauge is accurate before tearing down a engine.
Click to expand...
For the second time: the OP stated that the pressure had been verified with a mechanical gage. I did not say anything about tearing down the engine. The starting point for this would be the Lycoming troubleshooting guidance.
 
Oil Pressure

After re reading the posts from the OP I have another idea. There are several small pipe plugs inside the engine. The oil pump has a pipe plug. I can't remember if all oil pumps have this plug or just some. For example I believe ECI and Superior and maybe Niagara Air Parts all manufacture oil pumps. If one of these plugs is missing or fell out, with cold oil the pump would be able to overcome the loss of oil thru the missing plug. As the oil warms up the ability to overcome would diminish. If this is a plug problem it is likely that someone forgot to properly torque the plug and is now in the bottom of the sump.
Another less likely scenario is a problem with the oil pump itself.
I will look at the parts book but I believe all the plugs are either external or inside the accessory case.
 
Oil Pressure

I verified in the Lycoming parts catalog that there is one 1/8 pipe plug in the oil pump housing. If this were missing it would dump oil into the accy case and then into the sump.
Inside the accy case there are three additional plugs that go into the crankcase. Two of these close the aft end of the main oil galleries, one on each crankcase half.
I have seen numerous statements that the normal oil pressure fitting location reads oil pressure direct from the pump. Examining a sump this appears to be incorrect. The oil goes from the pump to the oil screen and then to the oil pressure port.
Marvel and Scott tell us that there is 8-10 psi less pressure at the forward end of the right main oil gallery. It is reasonable to believe that there is a further drop on the way to the left gallery and the main bearings. So 37 psi at the normal oil pressure connection would be 29# at the right front gallery and still less at the left gallery and front main bearing.
The green arc on the oil pressure gage is there for a very good reason. I cannot comprehend anyone believing that 37 psi in flight is acceptable. Do you have the same belief about Vne or G Limit??
 
Phenomflyer237 said:
Hello all , we have an o-360 Carb engine, after an oil change with the builder shortly after purchasing the plane the oil pressure dropped. At start we have 42 use to hang right at the green at 55. Then in flight it drops to 35 and the temp stays steady at 180-190 range. Here is what i have done
we did go from a tempest to a champion filter
w100 plus oil
Verified indications are correct via manual gauge.
changed oil and cleaned suction screen no debris found
changed the new oil filter and checked it for debris none found
Oil pressure relief-changed to the white spring part # LW-11713 went from 5 washers behind standard to 4 washers behind the white
initial start up oil pressure was at 70PSI,
In flight when the plane warms up the pressure decreases to 35 and stays steady.

Any ideas are welcome thanks
Click to expand...
Reviving an older thread.. some buddies that I fly with seem to be having the same issue with minor differences.. they have a Superior clone 360 engine with a cold air sump. Adjustable oil bypass housing instead of washers.. Oil pressure was 46psi in cruise. New to them plane, first time I flew in it, so I don’t know the history. We put an extra mechanical gauge and it seemed to match the installed readings. We check the ball, seat, and spring, gave it a few turns, checked the suction screen and cut open the oil filter.. all clean. New filter and oil, 60 psi in the runup. First flight and within 10 minutes, it’s back to 40psi.
I want to have them hook up the second gauge again but route it into the cockpit to test fly with it, perhaps the Advanced Oil sender reads low when the sender gets warm?
 
Taltruda said:
Reviving an older thread.. some buddies that I fly with seem to be having the same issue with minor differences.. they have a Superior clone 360 engine with a cold air sump. Adjustable oil bypass housing instead of washers.. Oil pressure was 46psi in cruise. New to them plane, first time I flew in it, so I don’t know the history. We put an extra mechanical gauge and it seemed to match the installed readings. We check the ball, seat, and spring, gave it a few turns, checked the suction screen and cut open the oil filter.. all clean. New filter and oil, 60 psi in the runup. First flight and within 10 minutes, it’s back to 40psi.
I want to have them hook up the second gauge again but route it into the cockpit to test fly with it, perhaps the Advanced Oil sender reads low when the sender gets warm?
Click to expand...
Two different types of pressure regulators used. If you put the wrong one on, it can produce normal pressures at low rpm and low pressure at high rpm. the ball must be centered over the hole. Some engines have a cage mounted on the case others have the cage on the adjuster housing. If there is nothing to hold the ball, you have low pressure most times, but not all.

I would be starting with the regulator, as everything after that in the diagnostics path is universally ugly. Be absolutely certain that all is right there. Could be too light of a spring . There are about 7 different varieties out there. Double confirmation of the sensor also a good idea,

Tell your buddy to do a prebuy next time. He would have been advised to walk away with 46 psi, as that typically means an engine tear down, though sometimes addressed with a new oil pump, via accy case removal.
 
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lr172 said:
Two different types of pressure regulators used. If you put the wrong one on, it can produce normal pressures at low rpm and low pressure at high rpm. the ball must be centered over the hole. Some engines have a cage mounted on the case others have the cage on the adjuster housing. If there is nothing to hold the ball, you have low pressure most times, but not all.

I would be starting with the regulator, as everything after that in the diagnostics path is universally ugly. Be absolutely certain that all is right there. Could be too light of a spring . There are about 7 different varieties out there. Double confirmation of the sensor also a good idea,

Tell your buddy to do a prebuy next time. He would have been advised to walk away with 46 psi, as that typically means an engine tear down, though sometimes addressed with a new oil pump, via accy case removal.
Click to expand...
I'm one of the buddies. We did do a prebuy, by a supposed experienced RV A&P, who missed several things. We changed out the spring in the oil pressure relief valve, using the standard most common spring which helped minimally. The ball looks good. Was thinking of trying the higher pressure spring next. What is odd though is that the oil temporature remains in low normal range despite the low pressure. Engine otherwise starts and runs great. We hooked up an analog oil pressure guage and it matched the Dynon indicator exactly but did not fly with it. Did run it up to 2000 rpm, however and it stayed consistent. What is the likelihood of the sender transmitting low only at hight temps? Other thoughts or suggestions?
 
9KiloMike said:
I'm one of the buddies. We did do a prebuy, by a supposed experienced RV A&P, who missed several things. We changed out the spring in the oil pressure relief valve, using the standard most common spring which helped minimally. The ball looks good. Was thinking of trying the higher pressure spring next. What is odd though is that the oil temporature remains in low normal range despite the low pressure. Engine otherwise starts and runs great. We hooked up an analog oil pressure guage and it matched the Dynon indicator exactly but did not fly with it. Did run it up to 2000 rpm, however and it stayed consistent. What is the likelihood of the sender transmitting low only at hight temps? Other thoughts or suggestions?
Click to expand...
Not sure what you mean by low normal range. You can put anything into the dynon system for range, doesn't mean anything. Lyc specs are between 50-60 PSI (varies by model) min, with 25 min at idle, so definately outside of the official range. I would definately try the strongest spring, as that will help to narrow down the source of the issue. I wouldn't leave it in there permanently though. You can also keep cranking on the adjuster if there is any travel left, as this is just a test. Please report the data after doing this and we can try to decipher what it means.

Did you check the seat that the ball goes into, looking for debris or deformation? Have you cleaned out the sump screen? That is a critical step. Also, run the engine for 15 minutes and start checking the oil for foaming. When you suck air into the system on the suction side of the pump, you get cavitation and makes the oil look like a milkshake from all of the tiny air bubbles. That would reduce pressure and tell us there is a leak / crack in sump or gasket failure. You have to catch it in the act though as the bubbles will go away after sitting for a bit.

Did you cut the filter open to check for metal?

Does pressure drop at idle or stay at 47?
 
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Phenomflyer237 said:
Hello all , we have an o-360 Carb engine, after an oil change with the builder shortly after purchasing the plane the oil pressure dropped. At start we have 42 use to hang right at the green at 55. Then in flight it drops to 35 and the temp stays steady at 180-190 range. Here is what i have done
we did go from a tempest to a champion filter
w100 plus oil
Verified indications are correct via manual gauge.
changed oil and cleaned suction screen no debris found
changed the new oil filter and checked it for debris none found
Oil pressure relief-changed to the white spring part # LW-11713 went from 5 washers behind standard to 4 washers behind the white
initial start up oil pressure was at 70PSI,
In flight when the plane warms up the pressure decreases to 35 and stays steady.

Any ideas are welcome thanks
Click to expand...
Constant speed or fixed pitch prop?
 
lr172 said:
Not sure what you mean by low normal range. You can put anything into the dynon system for range, doesn't mean anything. Lyc specs are between 50-60 PSI (varies by model) min, with 25 min at idle, so definately outside of the official range. I would definately try the strongest spring, as that will help to narrow down the source of the issue. I wouldn't leave it in there permanently though. You can also keep cranking on the adjuster if there is any travel left, as this is just a test. Please report the data after doing this and we can try to decipher what it means.

Did you check the seat that the ball goes into, looking for debris or deformation? Have you cleaned out the sump screen? That is a critical step. Also, run the engine for 15 minutes and start checking the oil for foaming. When you suck air into the system on the suction side of the pump, you get cavitation and makes the oil look like a milkshake from all of the tiny air bubbles. That would reduce pressure and tell us there is a leak / crack in sump or gasket failure. You have to catch it in the act though as the bubbles will go away after sitting for a bit.

Did you cut the filter open to check for metal?

Does pressure drop at idle or stay at 47?
Click to expand...
Except for the oil foaming..... I think all those questions have already been answered above.

Oil foaming is definitely an interesting avenue to look for that I don't think has been mentioned yet.
 
Notso said:
Except for the oil foaming..... I think all those questions have already been answered above.

Oil foaming is definitely an interesting avenue to look for that I don't think has been mentioned yet.
Click to expand...
I am not replying to the original poster from 7 years ago, just 9kilomike. I do not believe he has answered all those questions. maybe you can point out where he did.
 
lr172 said:
I am not replying to the original poster from 7 years ago, just 9kilomike. I do not believe he has answered all those questions. maybe you can point out where he did.
Click to expand...
I'm not talking about from 7 years ago. I'm talking about the post from two days ago about this specific airplane. Post #22. The one you originally replied to.
 
Full Throttle said:
Do ya think there may be some oil leadage behind the prop in the crankshaft plug? Or maybe the governor?
Click to expand...
If he had an external leak dropping pressure to 47 PSI, the engine wouldn't run very long before seizing. An internal leak is a very real possibility here.
 
Notso said:
I'm not talking about from 7 years ago. I'm talking about the post from two days ago about this specific airplane. Post #22. The one you originally replied to.
Click to expand...
thanks, missed that, but I do think rechecking the seat is a good idea. 9kilomike only said the ball looked good. It doen't say they installed a new spring or tightened down the adjuster more than a bit. As I mentioned extra time here is worthwhile, as it is the only easy fix to low oil pressure, beyond a clogged screen or suction leak and what happens with increased regulator pressure may give a clue to the source.
 
Why not just put 100lbs of air pressure in the oil gallery. Once the oil is blown out of the oil gallery, you should be able to hear an air leak inside the engine somewhere. Maybe. Kida like doing a leak down cylinder test.
 
Full Throttle said:
Why not just put 100lbs of air pressure in the oil gallery. Once the oil is blown out of the oil gallery, you should be able to hear an air leak inside the engine somewhere. Maybe. Kida like doing a leak down cylinder test.
Click to expand...
That’s an interesting idea.. maybe a “leak down” type test could help differentiate between a weak oil pump or loose bearing clearances.. Mahlon, is this something that you could shed some light on?
 
lr172 said:
where does he say that? Probably best to let taltruda or 9kilomike aqnswer these questions.
Click to expand...
Larry, thanks, you are right that we didn’t mention the prop type in the previous posts, but Notso happens to know the plane, so he’s right when he said Constant Speed.
 
lr172 said:
Not sure what you mean by low normal range. You can put anything into the dynon system for range, doesn't mean anything. Lyc specs are between 50-60 PSI (varies by model) min, with 25 min at idle, so definately outside of the official range. I would definately try the strongest spring, as that will help to narrow down the source of the issue. I wouldn't leave it in there permanently though. You can also keep cranking on the adjuster if there is any travel left, as this is just a test. Please report the data after doing this and we can try to decipher what it means.

Did you check the seat that the ball goes into, looking for debris or deformation? Have you cleaned out the sump screen? That is a critical step. Also, run the engine for 15 minutes and start checking the oil for foaming. When you suck air into the system on the suction side of the pump, you get cavitation and makes the oil look like a milkshake from all of the tiny air bubbles. That would reduce pressure and tell us there is a leak / crack in sump or gasket failure. You have to catch it in the act though as the bubbles will go away after sitting for a bit.

Did you cut the filter open to check for metal?

Does pressure drop at idle or stay at 47?
Click to expand...
The ball and seat look good. The owner, 9kilomike, put some additional turns on the adjuster, not sure how many but he said after an oil and filter change, and screen check (which were all good with no metal noted) they got the pressure up to 60 psi in the runup. In flight about 5 to 10 minutes, the pressure was back in the 40s and the pilot flying it did a return. As for idle, it’s lower than that, but I don’t recall the number, I’ll edit this post when I get that.
 
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Taltruda said:
That’s an interesting idea.. maybe a “leak down” type test could help differentiate between a weak oil pump or loose bearing clearances.. Mahlon, is this something that you could shed some light on?
Click to expand...
The oil system is a series of small controlled leaks, crank journals, cam journals,gear oilling ports, etc. The oil is thick, so you still maintain pressure. Air is thin so you don't build any pressure. You will hear air hissing from everywhere and that is normal. Better test is to keep tightening up the regulator. If pressure goes up, it is more likely bearings or other leak source. If the pressure remains low, more likely the pump or a leak before the regulator. A coomon source of lo9w pressure is a leak on the suction side, so best to start there. If the pump sucks in a bunch of air, it can't build as much pressure.
 
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Taltruda said:
they got the pressure up to 60 psi in the runup. In flight about 5 to 10 minutes, the pressure was back in the 40s and the pilot flying it did a return. As for idle, it’s lower than that, but I don’t recall the number, I’ll edit this post when I get that.
Click to expand...
If everything was cold when started, that is not too fart out of the norm. Was the pressure always 20 PSI higher when cold or was this new? Was the new oil w100 or 20w50? The former will have a larger pressure drop as the oil heats up.
 
lr172 said:
Not sure what you mean by low normal range. You can put anything into the dynon system for range, doesn't mean anything. Lyc specs are between 50-60 PSI (varies by model) min, with 25 min at idle, so definately outside of the official range. I would definately try the strongest spring, as that will help to narrow down the source of the issue. I wouldn't leave it in there permanently though. You can also keep cranking on the adjuster if there is any travel left, as this is just a test. Please report the data after doing this and we can try to decipher what it means.

Did you check the seat that the ball goes into, looking for debris or deformation? Have you cleaned out the sump screen? That is a critical step. Also, run the engine for 15 minutes and start checking the oil for foaming. When you suck air into the system on the suction side of the pump, you get cavitation and makes the oil look like a milkshake from all of the tiny air bubbles. That would reduce pressure and tell us there is a leak / crack in sump or gasket failure. You have to catch it in the act though as the bubbles will go away after sitting for a bit.

Did you cut the filter open to check for metal?

Does pressure drop at idle or stay at 47?
Click to expand...
And yet I've read in multiple sources that lycoming's like pressure around 75 psi in cruise. Am I missing something?
 
Treekiwi said:
And yet I've read in multiple sources that lycoming's like pressure around 75 psi in cruise. Am I missing something?
Click to expand...
That’s about right.. the accepted range is generally 55-95 in cruise, with temporarily as high as 115 of cold. Most engines are 70-85 in cruise.
 
lr172 said:
The oil system is a series of small controlled leaks, crank journals, cam journals,gear oilling ports, etc. The oil is thick, so you still maintain pressure. Air is thin so you don't build any pressure. You will hear air hissing from everywhere and that is normal. Better test is to keep tightening up the regulator. If pressure goes up, it is more likely bearings or other leak source. If the pressure remains low, more likely the pump or a leak before the regulator. A coomon source of lo9w pressure is a leak on the suction side, so best to start there. If the pump sucks in a bunch of air, it can't build as much pressure.
Click to expand...
Larry, you might be onto something.. the engine has a Superior cold air sump, and I’m not familiar with the suction side and how it differs from a conventional sump. I know the suction screen is relocated to the side instead of the back.. wonder where a suction side leak could be? We had 5.5 quarts registering on the dipstick with 6 quarts poured in.. that should be enough. Could the gasket be leaking between the sump and the accessory case?
 
Taltruda said:
Larry, you might be onto something.. the engine has a Superior cold air sump, and I’m not familiar with the suction side and how it differs from a conventional sump. I know the suction screen is relocated to the side instead of the back.. wonder where a suction side leak could be? We had 5.5 quarts registering on the dipstick with 6 quarts poured in.. that should be enough. Could the gasket be leaking between the sump and the accessory case?
Click to expand...
Gasket is possible, but not as likely. I am not familiar with the cai sump. The std sumps have a cast in channel fron the gasket sealing surface all the way to the bottom, hloding the screen. If the sump cracks or has a hole high enough up it can suck air. The channel exits at the sealing flat and there is a hole there as well as the case for oil flow. The gasket has a hole punched for this. It is possible that the gasket is torn on the inside, so could suck air and not create a visible leak. Again, if air is getting sucked in, you should be able to tell by looking at the oil. It will become foamy and look opaque after 15 minutes. The accessory case also has a similar channel feeding from the sealing edge all the way to the pump, and that could be cracked as well.

Still think you should be experimenting with increased pressure on the regulator. It would be very valuable to see what happens to the pressure after tightening that adjuster. . it will tell us how bad the situation is
 
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lr172 said:
Gasket is possible, but not as likely. I am not familiar with the cai sump. The std sumps have a cast in channel fron the gasket sealing surface all the way to the bottom, hloding the screen. If the sump cracks or has a hole high enough up it can suck air. The channel exits at the sealing flat and there is a hole there as well as the case for oil flow. The gasket has a hole punched for this. It is possible that the gasket is torn on the inside, so could suck air and not create a visible leak. Again, if air is getting sucked in, you should be able to tell by looking at the oil. It will become foamy and look opaque after 15 minutes. The accessory case also has a similar channel feeding from the sealing edge all the way to the pump, and that could be cracked as well.

Still think you should be experimenting with increased pressure on the regulator. It would be very valuable to see what happens to the pressure after tightening that adjuster. . it will tell us how bad the situation is whether it be a leak/bearing or a week pump.
Click to expand...
Taltruda said:
The ball and seat look good. The owner, 9kilomike, put some additional turns on the adjuster, not sure how many but he said after an oil and filter change, and screen check (which were all good with no metal noted) they got the pressure up to 60 psi in the runup. In flight about 5 to 10 minutes, the pressure was back in the 40s and the pilot flying it did a return. As for idle, it’s lower than that, but I don’t recall the number, I’ll edit this post when I get that.
Click to expand...
To clarify, the low normal was for oil temperature, only to point out that the oil temp was not going up despite the low oil pressure. Re other questions, we did check and cleed teh screen which looked fine, changed and cut the oil filter which also looked fine, replaced the spring with new one in the oil pressure relief valve using the #61084 which is the "standard" spring, and turned down the valve a couple of full turns. The pressure is higher now and normal at idle but dropped again within minutes after takeoff. Using 15W50 Aeroshell oil. Will look for foaming later this week as suggested.
 
9KiloMike said:
To clarify, the low normal was for oil temperature, only to point out that the oil temp was not going up despite the low oil pressure. Re other questions, we did check and cleed teh screen which looked fine, changed and cut the oil filter which also looked fine, replaced the spring with new one in the oil pressure relief valve using the #61084 which is the "standard" spring, and turned down the valve a couple of full turns. The pressure is higher now and normal at idle but dropped again within minutes after takeoff. Using 15W50 Aeroshell oil. Will look for foaming later this week as suggested.
Click to expand...
So, the ball rides in a somewhat tightly fitting bore in the adjuster assembly. Did you put the ball in there and insured that it could move freely? If the ball is getting hung up in there, it allows too much bleed off.
 
Taltruda said:
Larry, you might be onto something.. the engine has a Superior cold air sump, and I’m not familiar with the suction side and how it differs from a conventional sump. I know the suction screen is relocated to the side instead of the back.. wonder where a suction side leak could be? We had 5.5 quarts registering on the dipstick with 6 quarts poured in.. that should be enough. Could the gasket be leaking between the sump and the accessory case?
Click to expand...
Try adding 2 more qts of oil bringing the oil level to 7.5 qts from 5.5 and flying it. You might be surprised.... Good Luck, Mahlon
 
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