How do you test old style pcv ?

Small Block Mopar Engine

  1. Syleng1

    Syleng1 Karma is real and Life is short... FABO Gold Member

    Messages:
    2,380
    Likes Received:
    2054
    Joined:
    Jul 5, 2005
    Location:
    North Franklin, CT
    Local Time:
    6:13 PM
    7F60AAB1-CA78-4841-9E4C-A579956992AA.jpeg 1966 273 Commando engine. Does anyone have the proper procedure for testing the older style pcv valve Like the one above? I could not find that on the 66’ FSM. I replaced mine and now all the sudden I’ve got major oil consumption and smoke on start up and decel. The valve inside seems looser than the factory one I changed for visual reasons. I gave the old one away trying to help out a friend in need.
    The new one is from reputable dealer but I believe they are all over seas made.
    Thanks in advance.
     
    Last edited: Sep 27, 2021
  2. Plymouth 65

    Plymouth 65 Floorable Deplorable

    Messages:
    1,701
    Likes Received:
    1643
    Joined:
    Jun 27, 2016
    Location:
    Mich
    Local Time:
    6:13 PM
    I believe it just has a check ball type valve inside. I would make sure the ball moves freely and isn't gummed up. 65'
     
    • Agree Agree x 6
    • 66fs

      66fs FABO Gold Member FABO Gold Member

      Messages:
      6,165
      Likes Received:
      2670
      Joined:
      Sep 9, 2009
      Location:
      Greenwood, South Carolina
      Local Time:
      6:13 PM
      Never give old stuff away till you test the new stuff. Not sure how to test vacuum on one of those. It should not allow full vacuum. Plug it temporarily and see if the problem goes away. We just made sure they were not clogged shut and the check valve worked. Those will last forever, just soak in carb cleaner, flush and install.
       
      • Agree Agree x 2
      • Like Like x 1
      • Syleng1

        Syleng1 Karma is real and Life is short... FABO Gold Member

        Messages:
        2,380
        Likes Received:
        2054
        Joined:
        Jul 5, 2005
        Location:
        North Franklin, CT
        Local Time:
        6:13 PM
        I was not sure if the test as a pressure or vacuum test and what are the specs. Like the newer valves that have a spring and the spring wears out and the pcv leaks. That valve can be assembled with a multitude of springs rates. This one seems “looser” than others. I also want to put a gauge on that port to see what type of vacuum the engine is pulling and see if maybe the engine is pulling more vacuum than the pcv can handle and it is staying open always. In which case it’s garbage and I need to find a new way to evacuate the crank case.
         
        • Like Like x 1
        • Lord Sparky

          Lord Sparky Well-Known Member

          Messages:
          673
          Likes Received:
          505
          Joined:
          Dec 2, 2019
          Location:
          Carlsbad, California
          Local Time:
          3:13 PM
          They say to replace the Crankcase Ventilation Valve every 12 months. Excessive? Just spray some Gumout?

          D2B24B66-E85B-42A6-A6E8-FB6B5FC360DB.png
           
          • Agree Agree x 1
          • 66fs

            66fs FABO Gold Member FABO Gold Member

            Messages:
            6,165
            Likes Received:
            2670
            Joined:
            Sep 9, 2009
            Location:
            Greenwood, South Carolina
            Local Time:
            6:13 PM
            An engine should not pull that kind of vacuum. My brothers 67 273 would cruise at 18 inch of vacuum, no problem. Those valves were all the same as far as I know. If you changed the valve and all of a sudden there is a problem, it was probably what you just did.
             
          • 66fs

            66fs FABO Gold Member FABO Gold Member

            Messages:
            6,165
            Likes Received:
            2670
            Joined:
            Sep 9, 2009
            Location:
            Greenwood, South Carolina
            Local Time:
            6:13 PM
            We used to do that, back in the day when they cost a couple bucks. I wish I had kept more. I grab all the old steel ones I can get now, since I have never seen one wear out.
             
            • Like Like x 2
            • Murray

              Murray FABO Gold Member FABO Gold Member

              Messages:
              2,593
              Likes Received:
              1879
              Joined:
              Apr 19, 2010
              Location:
              San Jose, California
              Local Time:
              3:13 PM
              You boys are sure making me feel old. Here is the tool for measuring the effectiveness of your PVC. On a running engine pull off the breather on the v/cover opposite the PVC. Lay device over the hole. If there is adequate vacuum in the crankcase the check ball will be pulled into the safe zone. 100_2895.JPG
               
              • Like Like x 4
              • 66fs

                66fs FABO Gold Member FABO Gold Member

                Messages:
                6,165
                Likes Received:
                2670
                Joined:
                Sep 9, 2009
                Location:
                Greenwood, South Carolina
                Local Time:
                6:13 PM
                I'm old too, just never had a PCV tester.
                 
              • bcschief

                bcschief Well-Known Member

                Messages:
                1,309
                Likes Received:
                1023
                Joined:
                Feb 23, 2010
                Location:
                Crescent City Florida
                Local Time:
                6:13 PM
                Basically a PCV valve is a controlled vacuum leak to suck vapors from the crankcase the check valve and the spring are there to prevent backfires from entering the crankcase. So generally speaking soaking the valve in solvent to clean it should suffice. As long as the valve isn't plugged with gunk and the spring works the valve is good. You changed them in the old days because it wasn't worth your time to clean them.
                 
                • Agree Agree x 1
                • mopar head

                  mopar head Well-Known Member

                  Messages:
                  3,321
                  Likes Received:
                  1299
                  Joined:
                  Oct 21, 2008
                  Location:
                  Right here, can`t you see me?
                  Local Time:
                  6:13 PM
                  Does the old metal ones even have a spring?
                  The ones I have you can shake them and hear the check ball rattle, and to me means good to go.
                   
                • cudamark

                  cudamark FABO Gold Member FABO Gold Member

                  Messages:
                  9,131
                  Likes Received:
                  1552
                  Joined:
                  Mar 14, 2009
                  Location:
                  San Diego
                  Local Time:
                  3:13 PM
                  I guess I'm old too! I used to have one of those testers......I wonder what happened to it? Hmmm....
                   
                • dadsbee

                  dadsbee FABO Gold Member FABO Gold Member

                  Messages:
                  1,249
                  Likes Received:
                  2756
                  Joined:
                  Nov 25, 2020
                  Location:
                  Penetang, Ontario
                  Local Time:
                  6:13 PM
                  Give it to the Wife, should be able to suck air thru it from carb side, but not be able to blow any air out the engine side. Only test needed.
                   
                  • Like Like x 1
                  • cudamark

                    cudamark FABO Gold Member FABO Gold Member

                    Messages:
                    9,131
                    Likes Received:
                    1552
                    Joined:
                    Mar 14, 2009
                    Location:
                    San Diego
                    Local Time:
                    3:13 PM
                    I always just pulled the valve assembly out of the valve cover with the engine running, stuck my finger over the hole in the end of the PCV valve, and it it went "thunk" and the idle dropped a bit, it was good enough. If you had the wrong valve that allowed too much vacuum, you'd also have a rough idle. That might be tough to determine if you have a performance cam with very little vacuum to begin with. You may have to run a full compression/leakdown test to make sure your engine didn't just develope a problem.
                     
                  • Lord Sparky

                    Lord Sparky Well-Known Member

                    Messages:
                    673
                    Likes Received:
                    505
                    Joined:
                    Dec 2, 2019
                    Location:
                    Carlsbad, California
                    Local Time:
                    3:13 PM
                    Just did an internet search, none for sale, sometimes on eBay.
                     
                  • Dana67Dart

                    Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

                    Messages:
                    7,896
                    Likes Received:
                    5493
                    Joined:
                    Jul 16, 2017
                    Location:
                    Northern Colorado
                    Local Time:
                    4:13 PM
                    I have always tested them the following way:

                    1. With pcv valve removed from the engine, give it a shake test. If rattles thats good. If not clean it.
                    2. Pucker up and blow into both ends (one at a time and in normal operating position) one should allow air flow. One should not.
                    As for the amount of leakage under normal operating conditions????????
                     
                  • bcschief

                    bcschief Well-Known Member

                    Messages:
                    1,309
                    Likes Received:
                    1023
                    Joined:
                    Feb 23, 2010
                    Location:
                    Crescent City Florida
                    Local Time:
                    6:13 PM
                    I just looked in my 63 service manual and it recommends servicing the valve every 6 months by soaking the valve in carb cleaner and blowing out with air. If the valve is severely plugged it can be disassembled and cleaned the spring height is 9/16". It also says all V8s and the 225 use the same P/N valve but the 170 uses a different P/N.
                     
                    • Thanks! Thanks! x 2
                    • Like Like x 1
                    • Syleng1

                      Syleng1 Karma is real and Life is short... FABO Gold Member

                      Messages:
                      2,380
                      Likes Received:
                      2054
                      Joined:
                      Jul 5, 2005
                      Location:
                      North Franklin, CT
                      Local Time:
                      6:13 PM
                      Thanks Guys! But your kinda missing my issue in a round about way.

                      if the ball is not seating properly because the thing is garbage from bad production it could be sealing one moment and not sealing as the ball inside turns. Kinda like a bad valve job. If that makes sense. Typically that valve is closed and not sucking at idle or up to a certain amount of pull like say 5”hg after 5”hg it pulls off the seat creating the suction into the crankcase. But if the ball does not always seat it leaks. As for a spring- the spring can or cannot be there to control the ball especially when it’s a plastic ball because plastic is a lot lighter than metal.
                      I understand how it works but just could not find a spec to test when it “pulls open.” After all the dialogue- I now assume there is no spring or spec.

                      thank you!
                       
                    • kursplat

                      kursplat FABO Gold Member FABO Gold Member

                      Messages:
                      4,278
                      Likes Received:
                      3225
                      Joined:
                      Aug 24, 2010
                      Location:
                      so cal
                      Local Time:
                      3:13 PM
                      because every engine, even factory fresh, is never exactly the same as as the one next to it. the factory valves were probably a "best average" type of guess. whether you use one of these or not, there's some interesting info HERE
                       
                    • Bewy

                      Bewy Well-Known Member

                      Messages:
                      1,310
                      Likes Received:
                      819
                      Joined:
                      Jan 1, 2021
                      Location:
                      Australia
                      Local Time:
                      10:13 AM
                      The PCVs I have pulled apart do not have a ball inside, they have a spring & a pintle. A shape like a golf tee. That is because there is some airflow at idle around the stem of the pintle, through a carefully calibrated orifice. Once vacuum diminishes with more throttle opening, the pintle drops away increasing the gap for more airflow into the engine.
                       
                      • Agree Agree x 1
                      • cookietruck

                        cookietruck Well-Known Member

                        Messages:
                        1,062
                        Likes Received:
                        248
                        Joined:
                        Jun 25, 2012
                        Location:
                        alkdfnoi
                        Local Time:
                        5:13 PM
                        ...
                         
                      1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
                        By continuing to use this site, you are consenting to our use of cookies.