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Check those oil screens

vic syracuse

vic syracuse

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I come across many RV's whose operators forget to check the oil screen on the engine. It should be checked at least once per year during the annual or whenever the internal health of the engine is in question. Here is a picture of one I removed from an RV10 yesterday that should drive the message home. IO-540 with 10:1 pistons and only 600 hours. I don't know when the screen was last checked, but clearly there is lots of blowby. All of the chunks were carbon, the screen was about 50% blocked, with one cylinder at 48/80 and 54/80 and all of the leakage going by the rings.


 
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Vic, Did that engine have piston cooling jets? I have been wondering about exactly where that forms in the engine. I assume it has electronic ignition too?

Thanks.
 
Carbon

They are chunks of carbon from excessive blowby. I don't know if it has piston cooling jets. It could, as it is a Lycon supposedly rated at 317 HP (10:1) pistons.
I have seen small bits of carbon in other oil screens and in oil filters, but none ever this large or in such a large volume.

Vic
 
Ive seen one or two of those carbon chunks in my time, but that looks like the inside of a rock tumbler.

I also remove and inspect that screen at every oil change.

It seems funny to me that people take the time to cut open an oil filter, fan out the media and inspect for tiny slivers of material, yet ignore this "pre filter".
 
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I check my screen at every oil change. It only ads about 10 minutes and 1 crush washer to the job.

This last oil change I found a small piece of cork gasket from when I changed my valve cover gaskets. I was super careful scraping the old gaskets off but I obviously missed seeing this small piece fall in.
 
Lycoming SI

In addition to excellent advice already stated by Vic, I wanted to point out that Lycoming SI 480E addresses checking the suction screen.
As I seem to be not clever enough to post the .pdf link, I have added the germane section. There is more info included in the document.

I. Oil and Filter Change and Screen Cleaning.
A. At 25 hours after the first replacement/screen cleaning – oil change, filter replacement or pressure screen cleaning and oil sump suction screen check for new, remanufactured or newly overhauled engines and for engines with any newly installed cylinders.
B. 25-Hour interval – oil change, pressure screen cleaning, and oil sump suction screen check for all engines employing a pressure screen system.
C. 50-Hour interval – oil change and oil filter replacement and suction screen check for all engines using full-flow filtration system (except for engine models TIO-540-AF1A and -AF1B, which require 25 hour interval changes).
D. A total of four (4) months maximum between changes for systems listed under “A”, “B” and “C”.
 
Location

Might sound stupid, but my 540 has not run yet, and I am not at the airport, but where is the pre-filter located????
 
If its a parallel valve 540, then the screen is probably at the rear of the sump, offset to the right. Looks like a drain plug. If it is an angle valve, the screen is likely located on the left side wall of the sump.
 
How well does that engine run?

I have to ask...with those compression numbers, does it use a lot of oil, and does it make expected power? Rick
 
vic syracuse said:
I come across many RV's whose operators forget to check the oil screen on the engine. It should be checked at least once per year during the annual or whenever the internal health of the engine is in question. Here is a picture of one I removed from an RV10 yesterday that should drive the message home. IO-540 with 10:1 pistons and only 600 hours. I don't know when the screen was last checked, but clearly there is lots of blowby. All of the chunks were carbon, the screen was about 50% blocked, with one cylinder at 48/80 and 54/80 and all of the leakage going by the rings.


Click to expand...

From what I remember, the pickup screen in the oil sump should have the dirt on the outside. Is this the filter on the back of the engine? (screen instead of spin-on filter) If the photo is of the pickup screen, what was found in the spin-on or filter on the accessory case?

If this is the screen on the accessory case (instead of spin-on filter) shouldn't the crud be on the outside of the screen? IIRC, the oil flow is from the outside to the inside of the filter.
 
AN900-16

Is the part number for the suction screen gasket referenced in this thread. Yes, the oil flows from the inside to the outside. Here's a picture of the outside of the screen. Yes, there were particles in the filter, albeit much finer and smaller.



It did not impress me as making rated power, either. It is stamped at 317 HP by Lyon. Personally, I doubt that. But I figured the takeoff would be exhilarating if it truly had that much difference in HP. However, having just performed a top overhaul on mine and being impressed with the pickup in take-off acceleration and cruise speed, it actually seemed less than mine.
 
Part number?

Vic,
thanks for the help.
ACS has a list of crush washers but no luck on an AN900-16.

Is it a -15 maybe or a -17 perhaps??

Not checking that oil screen has always been due to not having that washer on hand.
 
N427EF said:
Vic,
thanks for the help.
ACS has a list of crush washers but no luck on an AN900-16.

Is it a -15 maybe or a -17 perhaps??

Not checking that oil screen has always been due to not having that washer on hand.
Click to expand...

MS35769-21 which is the same as AN900-16 or 1" ID size. Last time I ordered about 20 and gave 2-3 to each friend. It is the same for -360 engine.
 
I think I know why, because the AN # 16 is an MS #21 and if you look at the left column AN900 and go down to #16 there is none. If you look at the right column and follow down those numbers voila. I had to look once more myself and a little more carefully with Vic's post to find them.
 
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