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Blow by.

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  • #31

    Very clean set-up, and adapter.

    One thing I noticed -- If the line to the PVC valve is constant "open" suction to the manifold, how is the power brake booster maintaining a vacuum?

    Maybe I'm wrong -- someone else can verify?
    1960 Hard Top/430
    Thunderbird Registry Number 1231


    • #32
      I'm not sure. It has never been clear to me how a PCV valve does not constitute a vacuum leak. What I do know is that the power brakes have plenty of oomph, so I haven't been worrying to much about how the connection is made... besides, on the stock setup (or any setup) the vacuum is all coming from the same source: the manifold.

      I haven't driven the car in several days but the blowby problem remains equally.... problematic.

      Perhaps the first thing that needs to be determined is whether the problem lies in the engine making too much blowby or in the PCV system's improper operation. Any ideas as to how I can determine which is the issue?


      • #33
        Whew, this thread is getting long! But I remain baffled. Here is a brief review:

        I'm getting too much blowby on a recently rebuilt engine. Even with a pcv valve correctly installed, there is enough blowby that it will pump OUT of the oil filler cap. The wider open the throttle, the greater the problem.

        At idle in gear, I see the blowby coming out the hood scoop. At idle in park or neutral, I no longer see it. Compression was between 140 and 150 when last checked. Adding heavy weight oil to the cylinders caused compression to jump to 180.

        I get no smoke out the tailpipes, except perhaps initially as the car warms up, and I'm pretty certain that that smoke is merely condensation. It's minimal.

        The spark plugs were clean as a whistle before I fixed the vac. advance; now they are looking normal with a slight lean towards the rich side of things (may have been from letting it idle too long when I last checked).

        I'm curious about the filter Alexander described at the road draft tube hole. That is where I have always had my PCV installed. I know that the blowby comes out of the oil fill tube more liberally than out the draft tube hole.

        I need to know the cause of this problem before I go crazy! hehehe. Please help me to pinpoint the problem! I'm trying to save pulling the engine apart for the last possible resort


        • #34
          There is a rectangular mesh behind the blow by pipe. This can can get clogged with oil and residue and cause blockage. You can get it out and clean it using long nose pliers.
          1959 Hard Top
          1960 Golde Top


          • #35
            I don't think my car has the piece you describe. It was probably lost when the engine was apart before I bought it, like the oil baffles for the rockers and the lifter valley. I will have to consult the crankcase ventilation system diagrams in the manual more thoroughly.

            Byersmtrco mentioned something about a top end oiling problem possibly relating to this problem... how might such an issue affect blow by?


            • #36
              I read something on a BMW forum where a guy had excess blow by after cleaning the top end of his cylinders. He thought some carbon had fallen around the pistons and gummedup the rings. The people on the forum suggested pouring somne ATF into each cylinder and then letting it sit, later starting the engine to let it burn off. It fixed his problem. Have you guys ever heard of doing that?


              • #37
                Ah! I'm sorry about making so many consecutive posts, but I have some updated information.

                I adjusted my vacuum advance by looking at the timing marks on the crank pulley, applying the spec amount of vacuum with a pump, and then observing the change in the timing marks. I got the advance curve looking much, much more like it should than it was before, and the car is running much better! But I'm telling this info because the change seems to have affected the blow-by situation substantially.

                Formerly, after turning off the engine, blowby would smoke out for a while after the engine stopped. Now, there is almost none. Formerly, revving the engine in park would produce visible blow by overflow. Now, it doesn't.

                I noticed that my PCV valve was vibrating at idle in park. This seems abnormal.

                Unchanged: I still get some blow by out the hood scoop at idle in gear when I have the stock oil cap installed. Also, even with the "closed" pcv style oil cap installed, I get some gas entering the passenger compartment when accelerating. Not surprisingly, acceleration is what makes by far the most blow by. It is significantly reduced though now that the advance has been fixed.

                Also, I did a compression test on with the engine hot. The numbers are as follows:

                1 154
                2 153
                3 152
                4 146
                5 150
                6 153
                7 151
                8 150

                The plugs were odd looking. Some had a touch of pink on one side. Some had a greenish dust on them. Others looked pretty normal. I have photos if they would be of any use.

                Do things sound normal now, or do I need to keep looking for a problem?


                • #38
                  The trans fluid trick does work. I put it in a 66 i bought that was sitting since 1977 and the motor was stuck. To me it sounds like one of your rings is broke or linned up wrong. just a guess. I hope not though. .......Bill


                  • #39
                    The trans fluid trick does work. I put it in a 66 i bought that was sitting since 1977 and the motor was stuck. To me it sounds like one of your rings is broke or linned up wrong. just a guess. I hope not though. .......Bill ps that thing will smoke like crazy when you start it but it was worth it...........


                    • #40
                      Thanks for the info Bill. Do you just pour it in there and let it sit? How much? For how long? Engine hot or cold?

                      I think it's worth a try.


                      • #41
                        Were the cylinder walls checked for vertical grooves prior to honing?


                        • #42
                          Yes, they were thoroughly checked and in very good condition.


                          • #43
                            I think I finally have my answer to this problem. Please tell me if you agree.

                            When I got my replacement rings from the store, I carefully compared the new set against the old, checking the angle of the outer edge and the bevel on the inside edge. I found that the bevel was in the wrong place on the new rings (assuming the old were correct)--when oriented properly with respect to the outer edge, both rings compression rings had the bevel on the same side, both top or both bottom (can't recall which). The old set had had one with the bevel on top and the other with it on the bottom.

                            I returned the rings and had them send me a new set. It had the same "problem," so I called the manufacturer to ask them about it. They indicated that the rings should be correct and that I should install them as marked regardless of the bevel's orientation.

                            Well, according to some info I obtained on another forum, the bevels should be on opposite sides. I suppose my rings were defective, because I installed them as instructed, and apparently one of them is in there upside down.

                            Does this sound like a plausible/likely explanation to you guys?


                            • #44
                              Yes it does...
                              The 1960 Ford Thunderbird. The WORLD'S most wanted car....

                              VTCI Member#6287.


                              • #45
                                Hi peeeot,

                                I've been wondering how things are going.

                                From reading Steve Christ's book on the big block ford ... the condition of valve guides and seals can aggravate the blowby .

                                If I had your car I'd be very pleased with it.