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Low compression in one cylinder 1960 259

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  • Engine: Low compression in one cylinder 1960 259

    I’m nearing the point of putting my ‘60 Lark wagon back on the road after being parked for nearly 25 years. It has 54,000 original miles. I have done an engine reseal, installed new dual exhaust, and bought one of Jeff Rice’s 4 barrel intakes. I’m using a new Edelbrock 500 CFM carb.

    It has a fresh tune on it, and it runs very well with a smooth idle and acceleration. As part of the tune I decided to run a compression test on all 8 cylinders since I had the plugs out. I’m getting 120 to 140 on all cylinders, except for #3 which tested about 75 pounds.

    The exhaust does smoke a bit. Since it’s running well overall, I’m not suspecting leaky valves but rather stuck or worn rings. Am I on the right path?

    I’m hoping once I start driving it regularly the rings will loosen up and it will smoke less and the compression in that one cylinder will improve.

    Would any fuel additives help things out, like some Marvel Mystery Oil in the fuel? Or straight down the carb? Or just drive it and watch the oil and see what happens?

    Thanks for your opinions.

    Michael

  • #2
    Do a "wet" compression check. If the number comes up, then you are correct about ring sealing. If it stays about the same, then I would think a valve, which was my original thought. It may not be a burnt or worn valve, but just something stuck on a seat.
    Gary L.
    Wappinger, NY

    SDC member since 1968
    Studebaker enthusiast much longer

    Comment


    • #3
      Since you know it's #3 cylinder, why subject the other spark plugs to the snake oil? Maybe get #3 down in the hole, remove the spark plug, pour in a cup of diesel and watch what happens over a few day's time. If the rings are stuck, the diesel should drain down. If the rings are good, some of it will still be in there, so cover the plug hole with an old towel and crank the engine over several revolutions to clear any residue. Reinstall the plug, drive it and watch what happens. On rare occasions, stuck rings do free up, but not usually.

      Change the oil and filter after 500 miles.

      (Soon now will come, "Stude V8s don't need much compression to run; 75# is plenty. I drove one like that for twenty years, sold it to a neighbor who's still driving it." ;>)

      jack vines
      PackardV8

      Comment


      • #4
        For some reason, of all the Studebaker V-8 engines that I have seen with one bad cylinder, that bad/low/funky/weak cylinder was always #3 or #5. I do not know why, but it's always the middle ones on the driver side.

        Anyone know what's up with these two cylinders?

        Comment


        • #5
          I would pour some Sea Foam down #3 and let it soak for a couple days, then pour the rest of the can into the gas tank and drive it. You can also pour a can into the oil.
          In the 80's I bought an Olds Cutlass cheap due to the noise from a stuck hydraulic lifter. I put a can of Sea Foam in the oil, and before I drove 5 miles home, the engine was quiet as new.

          Comment


          • #6
            I would adjust the valves. Back in the good ol’ days valves would alway wear to the loose side, which didn’t hurt much except for being noisy. In the past couple of decades valve seat recession is the new problem, making valves tighter rather than loose. Whenever I’ve adjusted the valves on an engine that had some tight ones I was always pleased with how much smoother it runs.

            Comment


            • #7
              Pour 2 ounces of Kroil Kreen oil ($16 qt, free shipping) into the cylinder. Let it sit a week, it’ll soften the carbon around the rings.

              Comment


              • #8
                Just drive it a while and enjoy it while you mull over the problem.if your of an age tou will probably forget about the weak cylinder and worry about how to get that grin off your face, it makes you look guilty!! Enjoy, Doofus

                Comment


                • #9
                  I agree with studegary, do a wet compression check as that will tell you whether you have a ring problem of a valve problem. If the compression comes up considerably with a couple of ounces of engine oil poured into the cylinder, then there is a ring or cylinder wall problem, it it doesn't, then there is a valve problem such as a sticking valve stem or rust on a valve seat or face from the engine sitting with the valve open for a couple of decades. The problem with running the engine with a low cylinder is the engine will run rough especially at idle. I've used solvents such as diesel fuel, Kreen, Sea Foam etc. to try to free up stuck and gummed rings, sometimes they work and more times than not, they don't, but for a few bucks, a solvent is worth a try. Bud

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                  • #10
                    I can confirm that they run just fine with compression down to 75 lbs in number 3. My 64 259 has been like that for 30,000 miles. No worse and no better than when I discovered the "problem" about 10 years ago. In my case it is likely rings as I have had the heads off, valves done and adjusted the valves several times in the last 30,000 miles. It is curious that it seems to be the number 3 cylinder. Does any one want to speculate on the reason? Sure would like to know.
                    Bob
                    Bob
                    Welland Ontario
                    60 Lark Convertible
                    64 Daytona
                    sigpic
                    "They were meant to be driven ... so keep on cruizin"

                    Comment


                    • #11
                      I'm reasonably certain that Studebaker V8s run hotter on the driver's side. Whether that's got anything to do with low compression, I dunno'.

                      75 psi sounds to me like a broken compression ring. If that's the case, it won't change much over the next 1000 miles.

                      If it's a stuck ring, 1000 miles on fresh oil may fix it.

                      If it's a valve, it will get worse.

                      Of course you can settle the ring/valve quandary in five minutes with some oil down the hole and a compression gauge.

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