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  • Engine questions

    I have a remote mounted oil filter. Do I need to remove the Lycoming oil screen? I think I remember someone saying they were going to do it. I also need to tap off vacuum but haven't heard of any fittings to use. I am assuming AN840 "Hose Nipple Pipe Thread" fittings into the little ports on the head, next to the oil return lines on the heads.

  • #2
    From what little I can tell, I am not aware of a need to remove the screen as far as I understand it - which is a limited understanding.

    I am led to understand the screen or "rock catcher" is there to prevent big stuff blocking the pipes or getting into the important moving parts, and the filter is there to catch the dust, debris, and metal filings which will go through the system - basically to keep the oil clean.

    Unsure what "tap off vacuum" means. Do you mean "blank off"?
    Last edited by Battson; 10-14-2021, 05:00 PM.

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    • svyolo
      svyolo commented
      Editing a comment
      I need to get Manifold Pressure from somewhere, I thought they used the 1/8-27 ports on the heads next to the oil return lines. I have a couple of MAP sensors, and a fuel pressure regulator than need Manifold Pressure.

    • Nev
      Nev commented
      Editing a comment
      Is there one or two screens ? Mine has (had) a screen as part of the Vernatherm valve, and another screen on the rear of the oil Sump, which I believe is the "rock catcher". The second one I haven't removed so I'm not 100% sure.

  • #3
    Oh right - we changed to the air system. The air intake manifold isn't normally referred to as the vacuum system, that's what the vacuum pump does (if installed)

    Yes that's right, you need a little AN fitting with NPT one end and a hose fitting of your choice on the other. Remember either buy a fitting with a tiny orifice, or to install an orifice in the fitting (on the side that cannot reach the engine!!). This prevents fluctuations in the pressure reading.

    Comment


    • svyolo
      svyolo commented
      Editing a comment
      Yeah, my automotive lingo didn't work with aviation, which used to have a vacuum system. My bad. I heard Dynon and maybe Garmin have a software filter that doesn't require the small orifice, but my EFIS is GRT, so mine will have an orifice.

      But is the location correct? I have a Bob, narrow deck, PV 540. There is a 1/8-27 port next to what I believe are oil return lines (maybe not the correct terminology).

  • #4
    Here a couple of pics. Can't remember if you're using the Vans FWF kit, but if you are then it includes all of these fittings.

    MAP aft of the firewall, tube running the Sensor :

    36A84ECA-67E2-4BB7-A01D-5C17408C1265.jpeg
    Forward of the firewall, braided line running to MAP NPT port on the #5 cylinder :

    1ECC21A4-A54A-45D6-9BF1-4751C4C08F08.jpeg
    Top of a sawhorse , Vernatherm valve and oil screen. I don't know the answer to your question though, whether the screen should be removed. I've removed mine, but I do need to check too :

    F286CC8D-16B5-441D-B0AF-1DB08E5502CB.jpeg
    Nev Bailey
    Christchurch, NZ
    Builders-log
    YouTube

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    • #5
      I don't know the answer,but if it is upstream of the externally mounted filter, I believe you would have to clean it as well as changing the oil filter. If it is downstream, probably not. Makes me want to remove it whether it is upstream or downstream.

      Comment


      • #6
        The Lycoming operations manual for the 360 calls for “ Oil SuctionandOilPressureScreens At each 100 hour inspection remove suction screen. .Inspect for metal particles;clean and reinstalled. Inspect and clean pressure screen every 25 hours. The 540 may be different.

        Vans Aircraft sells a fitting that may meet your needs for MP


        Scott Ahrens
        Bearhawk Patrol Plans Built
        #254

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        • #7
          Further to Scott's reply above, I found a bulletin (partially copied below) which calls for either a Full flow filter or an oil pressure screen.

          The oil suction screen is installed in the sump and appears to be required regardless. So as I've got a full flow filter I'll keep the oil pressure screen removed.

          Not certain which one is referred to as the rock catcher, but I suspect it's the suction screen in the sump.

          2616BE94-40D7-47CC-9F26-96C4ACE43191.jpeg

          63A1D75D-88A0-4F38-B6E3-6DA4786E8D5B.jpeg

          Nev Bailey
          Christchurch, NZ
          Builders-log
          YouTube

          Comment


          • #8
            I wouldn't want to rely on the oil screen alone as the mesh is pretty coarse. So, a filter is more or less mandatory. In which case, I don't see any point in removing the oil screen - other than the fact it's a PITA to remove, replace and wire lock! At least it is on my RV-10 - on the Bravo with a 4-cylinder engine I have yards of space .....

            Comment


            • #9
              I'd like to offer a reason to remove screens...

              -The Lycoming Oil Fliter adapter replaces the screen housing with the filter.
              -AirWolf remote filter replaces the housing with an adapter that removes the screes.
              -The screens would eventually clog if I neglected or forgot to service them leading to an undesired outcome.

              BTW, AirWolf warns not to plumb the remote filter in series with the color. p.5 of the document below tells why.

              http://www.airwolf.com/aw/applicatio...rence_Data.pdf
              Brooks Cone
              Southeast Michigan
              Patrol #303, Kit build

              Comment


              • Nev
                Nev commented
                Editing a comment
                That's a very good point - I'll copy the relevant section and it's warning below for further comment. Thanks.
                Last edited by Nev; 10-17-2021, 02:13 PM.

            • #10
              From Brooks post above:

              AirWolf warns not to plumb the remote filter in series with the color. p.5 of the document below tells why.
              509A36BE-8D1B-4CD4-ADB4-2077315A4197.jpeg

              As I've plumbed mine in series, with a Vernatherm valve left in, I'm very interested in the above warning. Do they mean that the oil cooler must have its own thermostatic valve to reduce the flow of cold oil ? Or is a Vernatherm what they are referring to ?

              If the normal Vernatherm valve is left in place regulating oil flow to the filter, and then the cooler, is this still a risk ?
              Nev Bailey
              Christchurch, NZ
              Builders-log
              YouTube

              Comment


              • #11
                Originally posted by Bcone1381 View Post
                -The screens would eventually clog if I neglected or forgot to service them leading to an undesired outcome.
                If you managed to clog that screen, then you might have bigger problems than low oil pressure.... Something big would have to come apart. I think that's why they call it the rock catcher, it would only stop big stuff.

                That's how the engines ran for the longest time. No filters at all, just the rock catcher.
                Last edited by Battson; 10-17-2021, 04:41 PM.

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                • #12
                  Originally posted by Nev View Post
                  As I've plumbed mine in series, with a Vernatherm valve left in, I'm very interested in the above warning. Do they mean that the oil cooler must have its own thermostatic valve to reduce the flow of cold oil ? Or is a Vernatherm what they are referring to ?

                  If the normal Vernatherm valve is left in place regulating oil flow to the filter, and then the cooler, is this still a risk ?

                  That warning was very confusing. Too many double negatives!

                  Sounds like they are saying, when the filter lets the oil bypass, they think the cold slug of oil might clog in the filter if the filter is still in series. The Vernatherm AKA thermostatic value should bypass the cooler to prevent that happening.

                  So you need to have a Vernatherm installed, in their opinion, if you use their product.

                  That said, I have all mine connected in series and I have no Vernatherm, and I use the bypassing oil filter CH48109. No problems experienced. But I have a different product - not their product... so YMMV.
                  Last edited by Battson; 10-17-2021, 05:03 PM.

                  Comment


                  • #13
                    Originally posted by Battson View Post
                    If you managed to clog that screen, then you might have bigger problems than low oil pressure.... Something big would have to come apart. I think that's why they call it the rock catcher, it would only stop big stuff.

                    That's how the engines ran for the longest time. No filters at all, just the rock catcher.

                    The Photo below is from the internet, don't trust it, but it said it was Lycoming. The arrow points to the fine inner screen, the circle shows the solder joint of the inner screen.

                    I consider the use of "rock catcher" not reflective of the truth regarding Lycoming's oil screen. I've not yet handled my O-360's oil screen. A C-85 screen I serviced once upon a time was very similar to the photo below. The fine inner screen would catch sand grain size carbon particulate. I envision its ability to filter to improve as it catches sand grain size particles until it clogs up. I wonder if the oil will bypass a clogged screen? Hummmmmm.....

                    Everyone else will probably get away with it never inspecting it, but at best I will be left stranded....in the winter....with out survival gear.....in northern Canada. I think I need a good flint and steel in my survival vest. Burrrrrr.......


                    Screen Shot 2021-10-18 at 8.08.36 AM.png
                    Brooks Cone
                    Southeast Michigan
                    Patrol #303, Kit build

                    Comment


                    • svyolo
                      svyolo commented
                      Editing a comment
                      That was my thinking as well. If I leave the screen in, I have to change the filter, and clean the screen, at least periodically. Mine is coming off.

                    • Battson
                      Battson commented
                      Editing a comment
                      I guess my point was a little more about the consequences. This is a suction screen I believe? In which case, I assume you would see the oil pressure dropping off if the screen was blocking. But I was not aware of the possibility of the fine mesh strainer either, as I am not versed in Lycoming engines.

                  • #14
                    I am using a B&C filter on my engine build for the Patrol which completely replaces the Lycoming oil screen and housing. . I have cleaned these original Lycoming oil screens many times they tend to catch the larger chunks of carbon only. I recently replaced this screen on my Citabria with a B&C and after cutting apart a few filters I think the B&C does a far better job of filtering. I also note that my oil stays much lighter in color during the 50 hours between changes as compared to even 25 hours on the original Lycoming pressure screen.

                    Comment


                    • #15
                      Just as the best pilot procedure is the one that the pilot doesn't have to do, the best maintenance procedure is the one that doesn't have to be done. Saving a step in the oil change will minimize opportunity for error and contamination, and make more time for doing other things like flying or farting around on Facebook.

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