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  #1  
Old 02-17-2022, 07:01 AM
grubbat's Avatar
grubbat grubbat is offline
 
Join Date: May 2012
Location: Ga
Posts: 729
Default Lycoming Low Oil Pressure on Final

I0-360, about 200hr SMOH, recent oil and filter change, Victory multi grade aircraft oil (winter operation), 20 minutes into flight, on 10mile final, no traffic, beautiful evening.......

Started decent on the ball, pulled power, EFIS says in my headset “ oil pressure!”

Daydreaming is over, got a situation now. My approach is such that I can glide in so if engine quits, no problem. However, engine doesn’t quit and land normally and taxi back to hangar watching oil pressure follow rpm.......low rpm very low oil pressure. Time to troubleshoot now that I got it back in the hangar.

Pulled spark plugs to aid in turning engine over to check oil pressure and also to look for catastrophic damage on plugs. None found.

Check Indication issue. Before you decide you have a problem, first rule out the measurement system, in this case the sending unit and gauge. I installed a mechanical test gauge that works and installed on rear of Lycoming bypassing the oil pressure orfice. No oil pressure. Removed plug on front of engine case and installed mechanical gauge. No oil pressure.

Probably have a pressure relief issue but decided to drain oil over magnet and check oil filter and also pull oil drains that have magnets attached. No metal found in oil or on magnets. Checked oil filter and no particles found. Pulled oil strainer and it looked normal. Removed pressure relief valve. Ahhhhhh

The ball in the pressure relief valve is metal but Lycoming says don’t use magnet to remove so it takes a little work to get it out without disturbing the evidence behind the ball. After removal, I found the source of the low oil pressure.

On the seat, was positioned a very small metal ball, about the diameter of the head of a ball point pen. Too small to be a ball bearing. Large enough to mess with my oil pressure at low rpm.

Did it come from my new oil or new oil filter?
Or maybe from the mags?

I have a picture of the little devil but not sure how to post.

Anyway, reinstalled everything and added multi grade 15w oil and cranked several times to prime oil. Cranking show 50psi so maybe no damage. However, I’ll be throwing money at changing oil and filter every couple of hours and monitoring oil for excessive wear. Better safe than sorry.

EFIS verbal warning along with flashing light was definitely the ticket here. The verbal warning got my attention and my focus a lot quicker than a standard gauge would have. My Twinkie has old mechanical gauges and I would not have noticed low oil pressure in the twin as fast as I did with this experimental EFIS.

While I do not like a lot of the modern technology, this old guy has to admit that it saved the day (and around $15,000 for engine inspection).

Forget about the time the EFIS took a puke a couple of years ago over a dark Alabama live MOA. Another story for another time..... EFIS name omitted to protect the innocent
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  #2  
Old 02-17-2022, 07:23 AM
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Plummit Plummit is offline
 
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Thanks for that write up Craig. One more thing to add to the organic hard drive if I face similar circumstances. If you figure out where the blockage came from please post.

-Marc
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  #3  
Old 02-17-2022, 07:32 AM
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Dan 57 Dan 57 is offline
 
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Location: LSZF
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Thanks for the report Craig. Since you were already on low power, I wouldn't expect engine damage either. Nevertheless, an oil analysis for the next few changes won't be a bad idea, same for filtering the oil (babbit/iron/alu would be first to show up).

As for posting pictures, Doug made a very visible link for instructions, nicely visible on the upper left corner of my screen, copy here: https://vansairforce.net/articles/Im...ums/images.htm

So you're saying this mini ball is about 1/32 in diameter? Wonder where it came from...
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  #4  
Old 02-17-2022, 07:44 AM
rockwoodrv9 rockwoodrv9 is offline
 
Join Date: Dec 2011
Location: Meridian ID, Aspen CO, Okemos MI
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Im still learning all the engine crapola so this may be something obvious. I get a low oil pressure light on my g3x when I cut power to slow down as I am landing. I assumed that was normal but reading this post, maybe I am overlooking something that could be a problem? Is it normal for low oil pressure as you cut power to idle?

One other symptom is I can not get my oil temps up over 140 this past winter. It has been unusually cold so I passed it off as normal because of the low outside temps.

I am interested in what you find out about this.
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  #5  
Old 02-17-2022, 07:54 AM
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rv8ch rv8ch is offline
 
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Location: LSGY
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Quote:
Originally Posted by grubbat View Post
...
Probably have a pressure relief issue but decided to drain oil over magnet and check oil filter and also pull oil drains that have magnets attached. No metal found in oil or on magnets. Checked oil filter and no particles found. Pulled oil strainer and it looked normal. Removed pressure relief valve. Ahhhhhh

The ball in the pressure relief valve is metal but Lycoming says don’t use magnet to remove so it takes a little work to get it out without disturbing the evidence behind the ball. After removal, I found the source of the low oil pressure.

On the seat, was positioned a very small metal ball, about the diameter of the head of a ball point pen. Too small to be a ball bearing. Large enough to mess with my oil pressure at low rpm.

Did it come from my new oil or new oil filter?
Or maybe from the mags?

I have a picture of the little devil but not sure how to post.

https://vansairforce.net/community/s...ad.php?t=45548

Looking at DanH's diagram, isn't the oil pressure relief valve after the filter? If I have this right, it's really strange that something like this could get there and block it open.
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  #6  
Old 02-17-2022, 09:21 AM
BoydBirchler BoydBirchler is offline
 
Join Date: Jul 2020
Location: Indianapolis
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Sounds as though someone used steel shot to clean parts (most likely is the gears for the accessory case). That one did not get blown off or rinsed off before magnaflux or assembly.
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  #7  
Old 02-17-2022, 10:45 AM
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grubbat grubbat is offline
 
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Location: Ga
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Default Pics of metal miniture ball

Thanks for the help on the pics. Here they are.
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Last edited by grubbat : 02-17-2022 at 11:20 AM.
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  #8  
Old 02-17-2022, 11:10 AM
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fl-mike fl-mike is online now
 
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use the "Manage Attachments" button at the bottom of the message screen to attach your pictures directly into the post.
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  #9  
Old 02-17-2022, 11:32 AM
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Planecrazy232 Planecrazy232 is offline
 
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Quote:
Originally Posted by grubbat View Post
Thanks for the help on the pics. Here they are.
That's a pretty amazing find.
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  #10  
Old 02-17-2022, 11:37 AM
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hgerhardt hgerhardt is offline
 
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Looks like steel shot to me too. Hopefully that was the only one.

Before you reassemble, take a razor blade and shave off the paint remnants where the copper sealing ring contacts the crankcase. The engine builder should have masked that off before painting.
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