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  1. #1
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    PCV Valve making noise

    Is it right for the PCV valve to make quite a loud ticking noise?

    I took it off to check it and the middle/inside bit is loose? But only passes air one way, so I guess the valve is working.

    Thanks Mark
    DAX with 4.6 RV8 re-built in 2014 using all new bits.

  2. #2
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    It has a plunger inside which will rattle if the assembly is shaken, but in my experience loud ticking in operation isn't normal - but I've no experience of the RV8.

    The plunger relies on oil mist from the engine for lubrication - so you could try squirting a little engine oil into the PCV valve to see if that helps. They're cheap enough to replace, so I suggest that's your next step. Otherwise, it suggests there's excessive pulsing on the vacuum signal.
    Alan

    CRC Thames Valley Regional Rep
    UK Rep for European Cobra Club (eurocobra.boards.net)
    Dax 427 DeDion - Huddart SBC 383

  3. #3
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    My vacuum at tick over is 22Hg. This has been confirm on 2 x gauges. When I Rev it goes down to 5 hg.
    What would cause high pulses?

    I will ask JRV8 to send me another.

    Thanks Mark

  4. #4
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    Mark,

    It's not a problem I've encountered encountered personally. If there's an oil catch can or anything else in the PCV circuit you could check those. Has the problem suddenly started? Are there any other symptoms - misfires, erratic idle, etc? In my experience, many problems with these old V8s turn out to be pretty simple - so I suggest you whack a new PCV valve in there and then see if you still have a problem.
    Last edited by conrod; 08-03-15 at 11:02 AM.
    Alan

    CRC Thames Valley Regional Rep
    UK Rep for European Cobra Club (eurocobra.boards.net)
    Dax 427 DeDion - Huddart SBC 383

  5. #5
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    Id research that oil catch tank you have installed, im not sure its needed and may affect the pcv circuit operation.

  6. #6
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    OK, if there's a catch tank then you need to check that out. I have one on my SBC stroker - there was so much churn from the stroker crank that without the catch tank I was getting too much oil entering the inlet manifold. I have mine fitted between the carb PCV vacuum take-off and the PCV valve. Mine wasn't vacuum tight when I bought it, so I had to take the top off and put silicone sealant around the flange to seal it. You obviously also need to empty it from time to time - if it has filled up with oil then the PCV valve wouldn't be seeing the inlet vacuum properly.
    Alan

    CRC Thames Valley Regional Rep
    UK Rep for European Cobra Club (eurocobra.boards.net)
    Dax 427 DeDion - Huddart SBC 383

  7. #7
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    Not being funny, but are you sure it's the PCV valve and not a tappet.
    Mike
    Cobraless


    I've often been asked, "What do you old folks do now that you're retired?
    Well, I'm fortunate to have a chemical engineering background, one of the things I enjoy most is turning beer, wine, Scotch and margaritas into urine.

    Life's good, live it.



  8. #8
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    Yes Mike, when I pull the hose off, the ticking stops. Definitely the valve. Also I have listened to the engine with a stethoscope, all quiet, no ticking.

    Plumbing is PCV valve to catch can, the out of can to front of carb vacuum port.



    Last edited by Dixie; 08-03-15 at 02:12 PM.
    DAX with 4.6 RV8 re-built in 2014 using all new bits.

  9. #9
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    Mark,

    It looks as though yours is the same catch can as mine. I blocked one port and blew into the other, and discovered it wasn't air/vacuum tight. Suggest you test yours, and if air escapes remove the top and smear silicon sealant all around the join.
    Alan

    CRC Thames Valley Regional Rep
    UK Rep for European Cobra Club (eurocobra.boards.net)
    Dax 427 DeDion - Huddart SBC 383

  10. #10
    Join Date
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    The PCV on my 4.6 does the same thing, but I dont have a catch can - connects straight to the front of the carb. Had a look and it doesnt appear to be faulty - I'll try replacing mine too.

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