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Getting nervous....... intermittent engine knock

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  • fh4ever
    replied
    years ago, my 51 ford had sticky valve....run fine one minute, the next it had a knockin sound with loss of power. sometimes it would go away after a few minutes... or a can of oil treatment would cure it for weeks. It had some miles on it along with some sludge (this was back in the non detergent oil days). after a couple of years of this, it was rebuilt and never had a sticky valve again.
    ditto post #2...Does the miss go away with the knock?

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  • Corbinstein0
    replied
    Like was said before. +1 on adding an oil pressure gauge, +1 on oil change, +1 on tune up. Basics.... see if that cures it.

    Another thing that someone mentioned. Modern Crap Gas is not healthy for a Studebaker. Generally wont hurt engine internals, but carb and fuel system another story.

    I use Non-Ethanol in all my OLD stuff, and anything that won't burn it up quickly.

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  • Studebakercenteroforegon
    replied
    As far as the knock issue, I am voting for a torque converter flex plate with hairline cracks around the bolt mounting area. Shift the transmission among the gears and the noise should respond to that.

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  • Mike Van Veghten
    replied
    As Jack notes about the fuel. Todays gas goes bad faster than gas in the 70's and earlier.
    I'd say, that if the gas in the tank is older than 1 year, drain it, and fill with fresh fuel. Try to blow the fuel lines and filters clear of the old fuel, and the same with the carburetor too. Clear out the old stuff as much as you can and start...fresh.

    Mike

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  • PackardV8
    replied
    A sticking valve is usually accompanied by a noticeable noise of a compression leak in the intake or the tailpipe.

    The troubleshooting I'd do always begins with a complete igniton parts replacement; spark plugs, plug wires, distributor cap, rotor, condensor. One such knock was caused by spark tracking inside the distributor cap. Another was a random crossfire between parallel plug wires.

    While all the spark plugs are out for replacement, run a compression test and let us know the results.

    On a car which has been sitting for that many years, completely drain the fuel tank and change the fuel filter. Old stale fuel contaminated with water can waste days of troubleshooting time.

    jack vines

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  • studegary
    replied
    I first thought that it was the beginning of a failing flex plate, but they usually do not go away. Have you used a stethoscope (long screwdriver) to better locate the source of the noise? You may have an oil supply problem to a bearing.

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  • tsenecal
    replied
    Does the miss go away with the knock? That would verify a sticky valve. If the car just has the oil pressure light, you may want to hook up an oil pressure gauge, so you know what you have there. Fuel pump knocks are not usually intermittent. Also, not sure if you changed the oil, but a fresh filter and new detergent oil might clean things up in there. Good Luck.

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  • jackb
    started a topic Engine: Getting nervous....... intermittent engine knock

    Getting nervous....... intermittent engine knock

    So I just bought this 62' Lark with 259 & AT. Last tags say 2006. Sat somewhere in VT all this time....... Engine starts right up and idles nicely. Coolant says good to - 10 degrees (looks like Prestone). It was obvious from the start that there was a "miss" which I'm guessing is an open valve (s) somewhere...... But today in trying to get the temp up to 180 (no luck), it developed a distinct "knock". I pulled each of the plug wires to no avail or change in the noise. Increasing the idle increased the noise. The noise soon went away completely. Engine is up on stands and in neutral. Went out and started up after 15 minutes and the noise (knock) began then went away......... ??
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