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Discussion Topic:
Engine knock
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Pauls39 |
04-26-2010 @ 8:23 AM
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Member
Posts: 81
Joined: Oct 2009
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Just one more off the wall thing possibility. Check the fuel pump. We had a member with a 53 which had a dual action fuel pump. It provides vacuum for the wipers when the engine vacuum drops, as when you accelerate. The line from the manifold deteriorated and when you turned on the wipers, it sounded just like a rod knock. As the others have stated try to track down the location of the noise before you jump to any conclusions.
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supereal |
04-26-2010 @ 7:19 AM
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Senior
Posts: 6819
Joined: Oct 2009
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No knock is good news. If it is a sort of thud, it is likely a main bearing. If it is more of a rap, a rod bearing is suspect, particularly if it gets louder as engine speed is increased. Rough running can often mean a valve train failure, such as a broken spring. Last year we had an engine come in that had developed a knocking noise. It turned out to be at least one rod bearing that had spalled because coolant leaked into the crankcase thru a freeze crack. As mentioned above, pulling spark plug wires will often give a clue as to whether a rod is involved. and you should be sure no accessory is at fault.
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TomO |
04-26-2010 @ 7:09 AM
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Senior
Posts: 7258
Joined: Oct 2009
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rdt52flthd, Use a screwdriver as a stethoscope to determine where the knock is coming from. Hold it to your ear and to the head above each cylinder. Also check around the fuel pump and the distributor.
Tom
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deuce_roadster |
04-25-2010 @ 9:03 PM
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Member
Posts: 284
Joined: Oct 2009
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I was sure I had a rod knocking but it turned out to be that I sucked one of the small brass screws that hold the butterfly to the carb shaft into a cylinder and there isn't much room up there when the piston is up. I now make sure I stake them so they can't unscrew. You can look down the carb throat and see if all 4 screws are still there. Just another possibility for you to consider--good luck.
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Norm |
04-25-2010 @ 5:56 PM
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Member
Posts: 85
Joined: Oct 2009
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Don't drive it until you fix it!! In 1958, when in high school, a friend had a very tired '52 Ford which we drove about ten miles each way to school. We were used to all sorts of knocks, etc., and weren't paying much attention 'til it made a very loud noise and the car coasted to a stop. It would crank, but not start. Bottom line: broken crankshaft. The only time I've ever heard of a flathead actaully breaking a crank! Just an old sea story. Norm
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37RAGTOPMAN |
04-25-2010 @ 12:49 PM
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Senior
Posts: 1965
Joined: Oct 2009
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if you remove one spark plug wire at a time, you can tell which cylinder is making the noise, if the noise is still there,after doing this, it might be a timing gear rattle,or something else. it hard to tell with out hearing the noise and limited information, hope this helps, 37RAGTOPMAN
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rdt52flthd |
04-25-2010 @ 12:25 PM
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Member
Posts: 46
Joined: Feb 2010
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I drove my 52 flathead about 10 miles at 55 and pulled into my drive when a very mechanical knock started, timed to rpms. Oil pressure & temp both normal. I'm using 20W50 & it's at the full level with no froth. I let it cool off, but when restarted it still knocked. Is there anything short of a complete rebuild I should look for first? Mileage is a believable 63,000.
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