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what are valve cover oil deflectors for, anyway?

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    #1

    what are valve cover oil deflectors for, anyway?

    On many, but by no means all, valve covers;
    there's a sheet metal plate directly under the oil fill, so that oil does not go directly down, but would presumably splash off of this plate.

    I'm pretty sure, iirc, that my own valve covers on my box/panther are like this. OK, just the one valve cover with the oil fill, anyway.

    What's it for exactly?
    Tags: None
    #2
    its more to keep oil from flinging up the tube and into the air intake than anything to do with filling. I suppose it also has uses if the cap were to go missing. Oil wouldn't be spraying up the fill neck.
    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC grandpa spec white and cranberry

    1984 Lincoln Continental TurboDiesel - rolls coal

    Originally posted by phayzer5
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

    Everything looks like voodoo if you don't understand how it works

    Comment

      #3
      10-4. To help prevent oil from being drawn out the tubes/holes. If you have a pcv or breather in the valve cover, the baffle helps keep them from sucking a lot of oil. And yes, under some conditions the pcv is blowing, not sucking and the breather is blowing and not sucking.

      Alex.

      Comment

        #4
        OK, makes sense.

        Follow-up.
        There's already a pcv valve in the lower intake.
        So why do you also need that tube that runs from the valve cover to just before the throttle plate? (the very tube that the valve cover baffle prevents oil from being sucked into).

        This might be related to the "yes, under some conditions the pcv valve is blowing...and the breather is blowing"
        Is the breather there to supplement the pcv valve and vice versa?
        And under what conditions --other than running boost, which I am not-- would one or the other end up blowing?

        Comment

          #5
          Originally posted by BerniniCaCO3 View Post
          OK, makes sense.

          Follow-up.
          There's already a pcv valve in the lower intake.
          So why do you also need that tube that runs from the valve cover to just before the throttle plate? (the very tube that the valve cover baffle prevents oil from being sucked into).

          This might be related to the "yes, under some conditions the pcv valve is blowing...and the breather is blowing"
          Is the breather there to supplement the pcv valve and vice versa?
          And under what conditions --other than running boost, which I am not-- would one or the other end up blowing?
          The hose is a breather. It's set up so there isn't a vacuum leak. Not too important with speed density systems. But Mass Air applications don't like the PCV systems sucking air that the Mass Air sensor doesn't know about.

          Comment

            #6
            air path. Air is being sucked out of the crankcase via the PCV valve. Its got to come from somewhere, a filtered somewhere preferably. Also, as mentioned, significantly important with mass air, lest you have an unmetered air source, aka a vacuum leak.
            86 Lincoln Town Car (Galactica).
            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

            91 Lincoln Mark VII LSC grandpa spec white and cranberry

            1984 Lincoln Continental TurboDiesel - rolls coal

            Originally posted by phayzer5
            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

            Everything looks like voodoo if you don't understand how it works

            Comment

              #7
              ohhh... *light goes off in head*
              got it.

              So that when the pcv valve sucks in one direction, air comes in from the breather... which is in front of the throttle plate, or, probably, in a mass air system, it would more likely be found right in front of the MAF sensor to be seen by the MAF and work correctly, no?

              Comment

                #8
                start up a little Toyota SOHC 4 cyl car without the oil cap
                sigpic


                - 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims

                - 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust

                - 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock

                Comment

                  #9
                  hah, did that on a volvo once.
                  What got me is that after I did that, I had to hook up the official volvo software (vida) to reset the now-skewed fuel parameters.
                  God help the poor soul at an independent; they'd have to send it to a dealer to fix it.
                  Stupid; you'd think fuel trim could reset itself after a couple miles of driving. Apparently it doesn't.

                  Now, I got why you can't leave the oil cap off a long time ago. The valve covers are open to the oil drain holes. The oil drain holes go to the crankcase/ oil pan. The crankcase goes to the crankcase ventilation...which goes to the intake.
                  You don't need a breather tube, to explain why leaving the cap off is a vacuum leak.

                  Comment

                    #10
                    so on a MAF system, that breather will go to in front of the MAF sensor?
                    Or, nevermind, if it goes to any point in front of the throttle, it'll still work out the same way?

                    Comment

                      #11
                      on a MAF 5.0, the breather hooks to the same spot it does on an SD car. Other models it taps somewhere between the throttle body and MAF sensor, sometimes at the throttle body, sometimes along the air intake pipe.
                      86 Lincoln Town Car (Galactica).
                      5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                      91 Lincoln Mark VII LSC grandpa spec white and cranberry

                      1984 Lincoln Continental TurboDiesel - rolls coal

                      Originally posted by phayzer5
                      I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                      Everything looks like voodoo if you don't understand how it works

                      Comment

                        #12
                        Originally posted by BerniniCaCO3 View Post
                        so on a MAF system, that breather will go to in front of the MAF sensor?
                        Or, nevermind, if it goes to any point in front of the throttle, it'll still work out the same way?
                        It goes after the MAF. Point being that the air that's being used has been accounted for by the MAF sensor. There shouldn't be any air entering the engine that the MAF sensor doesn't see.

                        Comment

                          #13
                          pcv/crankcase airflow directions
                          Attached Files

                          Comment

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