2002 F150 5.4 basically stock. 225K miles. I have recently noticed a lower engine KNOCK??

It does NOT knock ALL the time.. just MOST of the time.
Is prevalent around 1600-2300 rpm, I have NOT been able to powerbrake and DUPLICATE noise?

I currently have the front diff out so I decided to drop the pan and take a look. I even pulled EVERY rod cap ( 1 by 1 of course) and plasti-gauged them....just because nothing felt bad...

Everybody was around the .0015-.0025 range (it is plasti-gauge so....not an exact thing) Doesn't get better than that....so buttoned everything back together.

BUT what else could/should I look at, I'm at a loss here. I would have swore it was a rod but numbers do NOT lie. (btw i am a 30 yr Journeyman Tool & Die maker....ye si know what .001 vs .005 clearance feels like)

any secret squirrel stuff with this 5.4 ..

 

Checeked torque converter bolts, flywheel, exhaust manifold leaks.... all good so far. Even tried pulling 1 plug wire at a time and driving it ....still knock (you can make a knock go quite if you don't fire the cylinder) Removed serp belt...drove it... still knocked

 

Well, if it is serious, it will get worse. Anyway that has been my philosophy about funny noises. Noises are hard to diagnose. I've been fooled many times.

 

Some 5.4's had an issue with piston slap.

https://www.f150online.com/forums/v8...n-summary.html

 

I have heard a piston slap on this truck ....usually only about 5 seconds when its first cranked up...COLD.

anybody got noise stuff about timing chains?....I can't picture a chain making this KNOCK ...but as I have stated....i am baffled.

 

youtube is my friend. By following a dead link in hte piston slap thread....i went to youtube to look for f150 noises...
I may have found my culprit... catalytic converter?

he's a little long winded but...sounds EXACTLY like what I'm hearing. Must figur out how to diagnos.

 

Beat on the converters with a rubber mallet.

 

Finally caught a break.... It was rattling pretty good upon first fire...i crawled under and could actually FEEL the knock INSIDE the front converter on the drivers side...

 

Thanks for letting us know! Glad it wasn't engine mechanical.