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ECI-360 oil pressure problem solved

Earl Findlay

Active Member
I've been BUSY building my -14, but still managing to take the -9A up once per week or so. Anyhow I've been having a bit of a low oil pressure problem on it recently. I've been running the motor at 5 quarts, because that's where it seemed to be happy. Well, the last two flights the oil pressure has been around 55 psi. That's 15 psi lower than I am used to. Well, today I wiped down the dipstick (It has markings every 2 quarts, so 4, 6, 8, etc. quarts) to service up the oil. Turns out I have been running it closer to 4 quarts than 5 quarts. Good thing the minimum is 4 quarts.. phew.

I have not flown the airplane yet (tomorrow), but I suspect now that I am up around 6 quarts, my oil pressure "problem" will be gone.

Moral of the story: with the dipsticks that only read every 2 quarts, it's hard to tell where the middle quantities lie. My takeaway is, just keep the **** motor at 6 quarts and call it good.
 
Oil Pressure

For parallel valve engines with standard sump 6 qt oil level will have no effect on oil pressure. IIRC the Lycoming minimum for these engines is 2 1/4 quarts.
Some angle valve sumps require a higher minimum oil level.
Lycoming's or Lyc clones like high oil pressure. A sudden drop of 15 psi should have required an immediate investigation. Could be as simple as trash under the oil pressure relief ball or it could be something really bad.
Oil pressure near the top of the green arc is beneficial to the valve train. There is no downside to high green oil pressure.
 
Make your own calibration for your specific set up. No way the same engine installed on a nosewheel aircraft reads the same oil quantity as if it were installed on a tailwheel aircraft. Or if the sumps are changed to cold air intake types.

Add 3 qts and put the dip stick in. Make a mark on the dip stick. That should be the lowest amount. Then add 1 qt at a time and mark it. You will soon see that the measurements are not linear, meaning just because you see oil between 4 and 6 does not mean you have 5 qts.
 
Oil

The M1A appears to have the same or similar sump as early angle valve 360's. it is wider and flatter, hence the need for a higher minimum. That sump is popular with builders who wish to convert a parallel valve engine to front mounted injection on a reasonable budget.
 
For parallel valve engines with standard sump 6 qt oil level will have no effect on oil pressure. IIRC the Lycoming minimum for these engines is 2 1/4 quarts.
Some angle valve sumps require a higher minimum oil level.
Lycoming's or Lyc clones like high oil pressure. A sudden drop of 15 psi should have required an immediate investigation. Could be as simple as trash under the oil pressure relief ball or it could be something really bad.
Oil pressure near the top of the green arc is beneficial to the valve train. There is no downside to high green oil pressure.

Thank you for these details.

I know that you say that it should not make a difference, but I serviced with two quarts of oil yesterday, and went flying today. Oil pressure was in the high 90's on takeoff with the oil temp around 110 degrees. With the oil temp around 180 degrees in cruise, the oil pressure settled back in to around 80 PSI.

So, while you say that adding oil should not make a difference to my oil pressure, in my case, it most certainly did.

Thanks for the input. If you have any thoughts, feel free to share them! Always learning...
 
If adding oil makes a difference to oil pressure, it would mean that the oil pump was sucking air previously. They are a fixed displacement pump. If the inlet to the pump is under the level of the oil then the pump produces flow (against restriction) and the amount of restriction, rpm of the pump, as well as the viscosity of the oil, determine the pressure of the oil in the galleries as seen on the gauge.

Mike

Thank you for these details.
...........
So, while you say that adding oil should not make a difference to my oil pressure, in my case, it most certainly did.

Thanks for the input. If you have any thoughts, feel free to share them! Always learning...
 
Oil

If adding oil makes a difference to oil pressure, it would mean that the oil pump was sucking air previously. They are a fixed displacement pump. If the inlet to the pump is under the level of the oil then the pump produces flow (against restriction) and the amount of restriction, rpm of the pump, as well as the viscosity of the oil, determine the pressure of the oil in the galleries as seen on the gauge.

Mike

Agreed, however, low oil quantity means less is available for sitting around and cooling off.. perhaps the low quantity was also running hotter? I've seen oil pressure drop in race car engines if the oil started breaking down.. maybe adding a few quarts introduced enough fresh oil to restore viscosity?

Also be aware that there is a oil suction screen in the sump that most guys don't know about. Not the oil pressure screen, or oil filter, but the one that catches junk before the oil pump. I cleaned one before and the pressure came up quite a bit. .
 
Good points.
Really high oil temps and therefore low viscosity could do it. Gauge?

You're totally right with cavitation of a pump due to suction restriction. That would cause lower pressure but naturally not solved by just raising the oil level in the original posters engine.

Mike

Agreed, however, low oil quantity means less is available for sitting around and cooling off.. perhaps the low quantity was also running hotter? I've seen oil pressure drop in race car engines if the oil started breaking down.. maybe adding a few quarts introduced enough fresh oil to restore viscosity?

Also be aware that there is a oil suction screen in the sump that most guys don't know about. Not the oil pressure screen, or oil filter, but the one that catches junk before the oil pump. I cleaned one before and the pressure came up quite a bit. .
 
So, while you say that adding oil should not make a difference to my oil pressure, in my case, it most certainly did.

Not what I would call cause and effect. The fact that adding oil the next day resulted in increased pressure is not conclusive evidence that low oil level was the problem. Especially when 4 quarts is well above the level where cavitation is a risk on most sumps and this is an intermittent issue. You stated that you often fly at 4 quarts.

You would be wise to keep a close eye on this issue and look more closely at other potential cause. atypical oil pressure changes need to be looked at very closely to determine cause, as they can result in the pilot having a very bad day in the near future.

as others mentioned, its possible you hav the wrong dipstick and what you read as 4 is really 2. THough not sure how you could not catch that after several oil changes.

All of this said, I really don't know your sump and oil feed configuration. It is possible that your minimum really is 4 quarts.

Larry
 
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Also be aware that there is a oil suction screen in the sump that most guys don't know about. Not the oil pressure screen, or oil filter, but the one that catches junk before the oil pump. I cleaned one before and the pressure came up quite a bit. .

I'm sorry, but anyone who "don't know about" the suction screen is not truly qualified to be changing the oil!
 
Flew it again and the oil pressure was normal.

Is the general consensus to fly the airplane and be sure that there are no more oil pressure excursions? Is there anything to "check" at this point? Confirm that since the oil pressure was always in the mid-50's or above (and in the 70's below 2500' or so, especially at low power) I do not have cause for concern, as far as oil starvation is concerned?
 
Oil

Still no mention of exact model number and whether oil dipstick markings have been confirmed correct.
Searching for an operators manual for I0 360A1A will show drawings of that engine. The sump for the parallel valve M1A is apparently the same or similar to A1A. If you look at the rear view drawing you can see the cap for the suction screen. It is easy to see that low oil level in this sump is much more critical than with the sump used on the vast majority of 0 360 parallel valve engines.
if in fact the OP engine has that sump than it is possible that adding 2 quarts of oil increased the oil pressure. That would depend on whether the engine actually had six quarts of oil to begin with.
If the OP sump is the more standard deep sump there is no way that adding two quarts of oil changed the oil pressure.
It is likely there was some trash under the ball for the oil pressure relief valve and this trash worked its way out.
 
What else to do

Flew it again and the oil pressure was normal.

Is the general consensus to fly the airplane and be sure that there are no more oil pressure excursions? Is there anything to "check" at this point? Confirm that since the oil pressure was always in the mid-50's or above (and in the 70's below 2500' or so, especially at low power) I do not have cause for concern, as far as oil starvation is concerned?

If you want more things to check, I would do an pull change (even if it isn't due) check all of your screens & filters, then measure the oil going back in to know the calibration of your dipstick. Be sure to cut open the oil filter, clean out the suction screen (also get your finger in the hole to scoop out any carbon or trash) and maybe even send out the oil sample for analysis. Also stay current on engine out spot landings!
 
Oil

All the references I find call for green arc oil pressure in cruise 60-90 psi.
Some are happy with middle of the green. Some like high green oil pressure.
There are opinions that high green is better for valve train lubrication. Also opinions that low green pressure causes high oil temperatures.
 
If you want more things to check, I would do an pull change (even if it isn't due) check all of your screens & filters, then measure the oil going back in to know the calibration of your dipstick. Be sure to cut open the oil filter, clean out the suction screen (also get your finger in the hole to scoop out any carbon or trash) and maybe even send out the oil sample for analysis. Also stay current on engine out spot landings!

short of a catastrophic problem in the crankcase, a blocked filter or screen is not likely to show an instantaneous drop of 15 PSI. This excludes, of course, anamolies such as a rag left inside the engine during the build (You might be surprise how often this happens). Even less likely when you consider that it cleared itself two flights later. Trash stuck in the relief ares is far more likely.

Larry
 
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Ground issue?

I think I'd lean toward a ground or sender issue. Mine varies that much between flights, in the middle of flights, and I can occasionally see it jump up or down. I'm pretty sure it's just a ground issue somewhere and I'm not all that worried about it. Oil temp does the same thing sometimes. It'll just jump up or down ten or twenty degrees. One minute it's running 160 degrees then it's 180. Sometime when the cowl is off I'll clean a ground wire or two...
 
What type of relief valve cover do you have? Can look like a Bat Masterson derby hat or an Abe Lincoln stove pipe hat or the stove pipe with an adjusting stem and nut out of the top. If its the derby type there needs to be a cage inside the engine to center the relief valve ball to it's seat. There is no cage used with the other two style caps. If you have a derby style cap with out the cage the oil pressure will be intermittent normal, high, low and in-between, as the ball never hits it's seat correctly all of the time.
something to check....
Good Luck,
Mahlon
 
I have flown twice more since adding more oil to the motor. Oil pressure is solid at 80 - 85 psi inflight. Looks like I dodged a bullet. :cool:
 
Glad to hear that.

Question: In your first post you said you saw OP of 55 psi, 15 psi lower than normal. That would be a normal of 70 psi. Now you are seeing 80 - 85 psi. Does the unexplained difference between the old normal of 70 psi and the new normal of 80 - 85 psi give you any pause?

No, not at all. Should it? I am not an engine expert my any means. If you have some concern or suggestions, I?m all ears. I?m here to learn.

My belief is that the engine has ALWAYS been run a bit low on oil and hence the lower pressures. I have a photo on my phone at 11,500? and the oil pressure there was 73 psi and temp was 198. Now I?m seeing 80-85 psi and 180 on the oil temp. Does that data support previously having lower oil quantity than optimal? I believe yes?

I?m seeing low to mid 80 psi and 180 degree temps at 7500? and lower. I haven?t had it up to 11,500? yet to do an actual like for like comparison.
 
No, not at all. Should it? I am not an engine expert my any means. If you have some concern or suggestions, I’m all ears. I’m here to learn.

My belief is that the engine has ALWAYS been run a bit low on oil and hence the lower pressures. I have a photo on my phone at 11,500’ and the oil pressure there was 73 psi and temp was 198. Now I’m seeing 80-85 psi and 180 on the oil temp. Does that data support previously having lower oil quantity than optimal? I believe yes?

I’m seeing low to mid 80 psi and 180 degree temps at 7500’ and lower. I haven’t had it up to 11,500’ yet to do an actual like for like comparison.

Yes, it should. Oil sump level in relationship to oil pressure is binary. It's basically all or none. It is not a gravity fed system, so level is irrelevant until the level is so low that the sump's port is no longer fully covered by oil, then pressure drops like a rock. The pressure will often go up and down like a roller coaster as the oil goes from covering to not covering the sump port due to movement of the oil surface. Most engines have a very consistent long term relationship between oil temp and pressure, assuming the same oil viscosity. The fact that yours is a moving target at the same temp is an indication of a problem. You need to re-read Mahlon's advice, as it likely explains your issue. His advice helped me solve this exact issue on the 540 core that I recently overhauled. It had obviously been running with this issue for a long time before I got it, based upon the log's history of oil related parts replacement. The A&P clearly never figured out the mismatch of parts. I had it addressed in 5 hours of flight thanks to Mahlon's generous posting of his extensive knowledge.

In my experience, the difference of 180 to 198* will NOT represent a reduction of 10 PSI. I suppose that different issues in different engines could cause this. I can assure you that the 80-55 PSI drop is not from oil temp, assuming temps compared are above 120. I have an engine in phase I now and watch this stuff closely. oil temps in the 160-185* range are consistently giving me 80-82 PSI at all altitudes with 2400+ RPMs.


Larry
 
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We spent the last few hours taking the various suggestions listed in this thread.

1. Relief valve cover was checked. It?s the ?stove pipe? type, and all checks out.
2. Suction screen is clean.
3. Oil changed, and sample being sent out. Approximately 5 1/2 quarts were removed, meaning that prior to servicing, the engine had about 3 1/2 quarts.
4. Oil filter clear of any visible causes for concern.

Took it up for another flight and oil pressure is rock solid in the low to mid 80?s.
 
Added 7.5 hours to the engine this weekend. Lowest oil pressure I saw at cruise was 78, highest was 88. Right there I'd expect it!

Oil sample should be back early this week, but I am feeling really good about things now. Based on all the great advice posted in this thread, I honestly cannot tell you WHY oil quantity alone has raised my oil pressure, but after 12+ hours on the motor since servicing up to 6 quarts, the oil pressure has been solid.

Any suggestions on how long I should have pressure back to the normal range before I take a passenger up with me (in other words .. until we know that it's truly fixed)? By the info I received here, I stopped taking passengers, thinking the risk was feeling too high, but I am starting to feel a lot better about things now. Any guidance on hours until YOU would feel comfortable riding with me would be most helpful.

Much thanks,

Earl
 
Added 7.5 hours to the engine this weekend. Lowest oil pressure I saw at cruise was 78, highest was 88. Right there I'd expect it!

Earl

If those were found with comparable oil temps, I would remain concerned. I see very stable oil pressures at similar temps over several years. Maybe others can comment on their experience, however, I would still be concerned until I understood why the pressure is changing. While I may be incorrect, I simply don't believe your low pressure was due to oil level, but was simply part of the erractic pressure swings that you are seeing. Cause and effect can be quite difficult to determine with intermittent problems. How do you know that the oil level addressed the issue when it only happened once or twice? It is possible that the disappearance of symptoms was simply coincidental to the adding of oil.

Most likely problem area is the pressure relief and I would want to pull it and put eyes on it. It only takes a few minutes to pull it.

Larry
 
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How does one know what the ?Lycoming equivalent? is for their ECI motor to know if this applies?

The ECi and now Continental Aerospace Titan engines are built to the customer's specification. They are based upon the Lycoming(R) parallel valve 320 and 360 designs but there are so many variants that direct comparisons are very difficult to make. Titan engines have many unique characteristics that improve on the original design like NiC3 plated cylinder barrels, light weight oil sump, thrust washer equipped crankcases, etc. The dimensions are the same as the 320 and 360. Continental Aerospace also manufactures "stroked engines" with more displacement and power. Those are the 340 ( stroked 320) and 370 (stroked 360) engines. When you see all of the options ( displacement, carbureted, fuel injected, fixed pitch , constant speed, conical or dynafocal motor mount, front governor, rear governor, magneto ignition, electronic ignition, vertical induction, horizontal induction, and the various fuel delivery and ignition options, it become exponential. We build to the customer's requirements / mission.

I hope this helps answer your question, sort of........
 
Another great flight today. I added 1/2 a quart of oil, and then took her flying. Oil pressure 82 - 87 psi once warmed up. Yahoo!!

Blackstone Labs report came back. "Hi Earl. Very impressive results since the last time we received a sample. Even for a 255 hour motor, these numbers are well below what we usually see. Low aluminum, iron, and lead tells us you're running this engine right. Your sample gives us comfort that extending your oil change intervals from 35 hours to 50 hours should be of no concern. Keep doing what you're doing!"

I was ecstatic to receive such a fantastic report.

I continue trying to monitor for any potential problems with OP since making sure the quantity is always correct, but so far unwavering OP has been the only thing noted.

Engine hiccuped a bit today for just a split second; probably water in the fuel (I did not sample any, however) as its been raining some, and my hangar is not water tight. Still, that'll wake you up!
 
Steady oil pressure

I?ve been running an ECI IO360 for 8 years and have never seen a change in oil pressure more than a pound or so! Always run 7 quarts but I have cold air eduction so that may be different than what you are running. The point is, steady as a rock since new. What you are describing would make me investigate further than on this forum. Just my .02 worth.
 
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