5.4 Knocking on Cold Start Up

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Mar 7, 2017 | 11:22 PM

#16

2006f150bk

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Joined: Mar 2017

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help

i did just do an oil change about 800 miles ago and i did use the 5w-20 motorcraft synthetic blend oil and i used the motorcraft oil filter. i only stated the flexplate issue because thats what i thought it was. after the cold start the knock is real loud and after i warm it up and drive it the knock goes away any ideas what it could be?? The noise is coming from the bottom end underneath the truck

Mar 7, 2017 | 11:25 PM

#17

2006f150bk

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Joined: Mar 2017

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When cold, the engine has a loud knock from the lower engine that sounds exactly like a bad rod bearing. However, when the engine is warmed up but not yet driven the knock remains, until I drive it. I drive for a mile or two and no more knock. Also, when the knock is present and I give it a little gas, the knock will go away until the engine comes back down to idle.

Now what's weird is, today I started it cold and there was no knock at all.
Oil pressure is constant at about 3/4 up the gauge, I'm running 5W-30 motorcraft synthetic blend with a motorcraft filter. Any ideas?

Dec 9, 2023 | 01:16 AM

#18

jwhite67

3rd Gear

Joined: Mar 2023

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Quote:

Originally Posted by 2006f150bk

I have been having an issue with mine as well I have a 2006 f150 it's the 3v 5.4 after I let it sit for a while it will knock real loud From the bottom end like it's the transmission. After I drive it like two miles or so the noise will go away. I have a bad flexplate in mine I think it's hitting the starter and that's what it is im not sure though I've heard several things and I'm not sure what route to take at this point does anyone have these same issues?

my 2002 f150 xlt 5.4 2v does same thing. except mine does it idling. punch it and it will bark good sounds. i hate it. sounds like my flex plate as well. i just rebuilt trans and was alttle tight with end play on 4r70w but within spec. i still think its lower end. im REALLY curious about this piston slap. ive checked compression recently and had average of 160 on a fairly cold engine. it would seem piston slap would tear it up? the block or something. also i believei have a vaccum leak that could be a culprit tothis on going baby. i finally got it running on all cyliners ( dont buy motorcraft coils on ebay) and put shorty tube headers on her. if y9u find solut8on 0lease let us know.