351 cold knock

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May 4, 2013 | 09:44 AM

UncleTom

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Joined: Jul 2006

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351 cold knock

Hi all, i have a 93 f150 with the 351 and 115,000 miles on it. All babied miles and never seen snow. It has developed a slight knock and goes away with in 5 blocks. I associate it with piston slap as when it warms up the piston will grow in size and stop knocking. I have listened to it with a stethoscope and really cant locate it. Any help would be appreciated. Thanks

May 4, 2013 | 11:10 PM

husky390

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Joined: Mar 2007

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Quote:

Originally Posted by UncleTom

My 90 does the same thing. It will be really loud when it's been cold out and I haven't started it in a week. It comes from the passenger side of the engine. It usually stops once the engine warms up. I've dumped seafoam in the oil thinking the valleys are clogged but that didn't work. I have Marvel Mystery Oil in it now and when I change the oil I'm going to try Mobil1. Other than that I don't know what to do except drive it till she blows. Hope this helps.