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whistling noise: question on 302 anatomy (it's been a couple years)

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    #1

    whistling noise: question on 302 anatomy (it's been a couple years)

    I worked on my colony park obsessively like 2 years ago, so now I'm a little fuzzier on the vacuum line plumbing.


    I had the oddest squeaking, grinding noise that I would have sworn was a bearing or maybe a very strange belt squeal. It wasn't (checked with mechanic's stethoscope) and I was lost for ideas... but then at like the 4th shop I went to, the service writer walks right over, cracks the oil cap loose, and it goes away. ah HA that explains a couple things.

    OK so what I understand is that the oil cap is on the valve cover, and the valve cover has a line that goes straight to the upper intake right? To engine vacuum.
    Vacuum btw remains at healthy levels; I have a gauge I put in the dash a while ago.

    So if it's making a whistling noise, it has to be sucking in (not blowing out)? As I write this I realize I could just put my hand over it or a sheet of paper then I'd know; but it's cold outside and my boots are off already

    Which would also explain why the noise appears at idle and goes away when I step on the gas-- vacuum drops.



    In conclusion it must just be a crappy seal on the oil cap, just the slightest break in that rubber ring on the underside and it's whistling through it like sucking air between your teeth? $5 from now I can fix this.

    But someone suggested pcv valve... not sure that makes sense if the noise goes away when I crack the oil cap. Is there any other possibility than just the oil cap seal, or it has got to be just that?
    Tags: None
    #2
    yeah... check the cap for crap around the seal... clean... might need a new seal/cap.

    I would think that the PCV was working well in that case as it's supposed to keep positive vacuum.

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

    Originally posted by gadget73
    ... and it should all work like magic and unicorns and stuff.

    Originally posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

    Comment

      #3
      make sure the tube from throttle body to valve cover isn't plugged. Its supposed to suck out of the back through the PCV valve, and feed air in through that tube. If the tube is plugged, the crankcase just ends up under vacuum all the time.
      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

        #4
        now the valve covers do NOT share an atmosphere with the crankcase, or do they?

        Comment

          #5
          Originally posted by BerniniCaCO3 View Post
          now the valve covers do NOT share an atmosphere with the crankcase, or do they?
          They do.
          1990 MGM: $50 E7 heads, HO cam, Holley SysteMAX lower intake, HO upper intake with an Explorer TB. LSC ECM. Lincoln logs into stock dual exhaust. K&N drop in air filter. Wide ratio AOD, 2400 converter with a 3.08 one tire fire out back. Car is less slow now. Then there's the '92 Beater. Dual 2.25" exhaust with shiny tips. Rumbles nice. Super slow. Burns oil too.

          Comment

            #6
            and if the valve covers are then connected to the intake... what is the purpose of a pcv valve if crankcase pressure is already venting through the valve cover?

            Comment

              #7
              The valve regulates flow. I think....
              1990 MGM: $50 E7 heads, HO cam, Holley SysteMAX lower intake, HO upper intake with an Explorer TB. LSC ECM. Lincoln logs into stock dual exhaust. K&N drop in air filter. Wide ratio AOD, 2400 converter with a 3.08 one tire fire out back. Car is less slow now. Then there's the '92 Beater. Dual 2.25" exhaust with shiny tips. Rumbles nice. Super slow. Burns oil too.

              Comment

                #8
                if the valve covers are open to crankcase pressure, it still could be the pcv valve then. hmm. I'll just swap it out anyway: it's been 3 years/ 20000 miles iirc.

                Comment

                  #9
                  The PCV draws oil fumes out of the crankcase. Fresh air comes through the throttle body to replace what the PCV valve sucks out.
                  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

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