Help diagnose my f150 5.0 - Update - pg 3

To be safe don't drive it any more. Get it to a shop, preferably a Ford dealer as they may have experience with that 5.0. I know that they had some cylinder out of round issues but that sounds like crank or rod bearing. Probably not flywheel cause it goes away after a while.

Doesn't sound too hot man. Actually sounds really bad....worse than it should missing 2.2 quarts. I'd get it to the shop if that is coming from your bottom end like it sounds

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it was conventional

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How do they know this?

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This goes away within 60sec and the truck runs smooth as can be

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Does it do it every time you start the truck? Even after a short trip while it's still warm?

Could be an exhaust leak but that would be a tick rather than a knock.

Get a short wooden broom handle or long screw driver, and put it up to the oil pan while engine is running.

You could have a couple things going on there, none of them good. I've seen piston slap make noise and then go away abruptly. While not the worse thing in the world, it's certainly not good. Never heard a rod knock or rod bearing get quiet so I'm stumped there. You can pull the coil pack off the plug, one by one, if it goes away you found you found your shitty rod bearing. If that's the case, trade the fricker in.


Just to make things more complicated, could be the oil pump. If the local $5 speedy lube put too heavy of an oil in your truck it could have ruined the pump.

My money is on the oil pump, but that's only because I don't want it to be a bottom end issue.

Pull the filter and check for metal shavings. And check your oil more often you dingus.

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Does it do it every time you start the truck? Even after a short trip while it's still warm?

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Yes it is every time. It seems to go away quicker when warm but I can't be positive.

- 100% not an exhaust leak. Maybe a cat went bad but not a leak

- and do what with the broom? What will that do?

- no shavings found when I changed the oil this week. Original oil was black. Will have to wait until Tuesday to check with the station that did the bad oil change.

I hope my research is wrong

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your main bearings are going. what you hear is affectionately known as a rod knock. it happens with excessive loading of an oil starved motor, or one going too long between oil changes. your main bearings are flat surfaced, but due to oil starvation have picked up an oval like eccentric shape, and the connecting rods are slapping around in that new larger clearance. the rebuild will fix this, but you CANNOT drive this vehicle

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your lifters are tapping.

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That was my first though but wouldn't that go away with a new oil change and Lucas oil treatment? I know sounds can be deceiving but it more pronounced from under the truck than under the hood. Lifters would be coming from the top end

Ok update time: cranked the truck after it sat over night. Screw driver on oil pan, nothing. Tracked down the sound to driver side catalytic converter. After sound went away I shut truck off then back on. No noise. Truck has to cool some for sound to be made. It sounds just like rocks in a metal can being rolled - I think the cat went to shite.
Also rod bearings or anything of that nature would give me bad oil pressure. I never had low pressure even before the oil change.

That video sounded like the bottom end, but good you got it figured out. You can get an aftermarket cat online for like $100

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video sounded like the bottom end,

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Its definately more pronounced under the truck. I can't confirm without a stethoscope but I'd say it's the cat. My ear pin pointed it to the cat pretty easily. I'm about to go to my company's mechanics house and let him listen. Ford tech is checking on cat warranty. He didn't know if it was 60k with the power train or 80k.