302 ghost knock
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Senior User
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From: Franklinton, NC
302 ghost knock
My 1984 F150 XLT 302 has a weird knock I cannot find the source Ive pulled the valve covers rockers are ok and pulled the timing cover, the cam is not walking. I have covered every inch with a stehescope. It is loudest when put in gear wheels chalked and standing in front of the truck just above the hood latch.. once you go to the sides it is not as loud.. and standing over the fan shroud it is not loud.. at idle you can hardly hear it. Nothing is loose on the front end.. any ideas?
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From: Franklinton, NC
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From: Broken Arrow , OK
The majority of the time I have heard a knock that is more prevalent when in gear turns out to be the lower end. Either a rod bearing or main bearing. The slack in the bearing doesnt show up until the motor is loaded and has resistance against it.
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From: Virginia
Get the sparkplug wires loose so you can easily take them off with it running. It may be easier at the dist cap. Get it running and pull the wires off one at a time. If you find one that makes the knock go away, that's the cylinder giving you the noise. Make sure you wear a thick glove, and or use long nosed pliers to pull the wires off. It should run ok with the wires sort of sitting in the cap so they are easy to get out.
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From: Virginia
If the knock is not affected by pulling the sparkplug wires off individually, then you can assume it's not a rod or wrist pin noise.
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From: Broken Arrow , OK
I had a Plymouth that had a plug wire burned up really bad . It was making a loud snapping noise , not quite a knock, but more than a tick. It would really act up if there a lot of people in the car with a load on the motor. I couldn't access the file he posted to hear the noise so I don't know if it is a definite knock or something else. I am just thinking of all the things that act up when the motor is loaded. We had a chevy truck that was one of our work trucks. The motor wouldn't knock at idle, but as soon as you put it in gear it would knock like crazy. That turned out to be the lower end.
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From: Franklinton, NC
It has new wires plugs and cap.. I done the night test and pulled one plug wire at a time.. noise is still there. I have yet to pull each belt to rule out the pulleys... if it is the pulleys I am going to go with a gilmer belt drive.. I had one on a chevy and had it set up right and it worked perfectly.