Lower Engine Knock (Identified)
 

Yesterday I replaced my CPS after the truck started stalling and not starting back up while hot. Testing the new on by letting the engine heat up to as hot as I could get it in my garage, about 197º, I noticed a knock coming from the bottom of the engine only at these temps. It's not a consistent tick like a slipped sleeve, but more like a random thud or knock that comes and goes. It's definitely louder underneath and isn't present cold. Any ideas? Here's a video:

So, how mechanical are you? I would not run the engine any more till you or some one is able to track down and fix that knock which could be either a broken flex plate, rod bearing or maybe a sleeve.

not try to be a WA but if you truck is in the garage running at 200*, what do you think you oil temperature is with no air moving across the motor? I Guessing it's working about as good as water.

I drove about 35 miles today and the truck drives absolutely fine. Nevertheless, I'll investigate this sound today. Drowssap, haha what's a WA?? But good point on the oil temp.

I have a new oil pan gasket I've been meaning to put in so I'll do that today. If I drop the oil pan I can inspect the rod bearings right? What else should I look for or open up to explore?

Wise*ss I believe...

OK. Got that off. I suppose I should change or clean the oil pick up screen while I'm in here? Anything else? How to I check the Rod Bearings?

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Before you took it apart, you could pull plug wires one at a time, and isolate a cylinder that is doing the noise (theory is that without explosions the force on piston and parts that move with it is reduced). There is a write up in the tech area on doing the main bearings in the truck. Don't want to see copper.

When putting it back together repalce seal gasket on the pickup tube, two dabs of loctite on the bolts.

FOUND IT!

All this time examining the rod and main bearings.. I took a break to pressure wash the oil pan. I took the plate off inside and guess what I found? This little sucker and when I picked it up, I dropped it because it was slippery with oil, and I'll be damned if it made almost the identical sound hitting the inside of the oil pan cover as the sound I was hearing with it running. I guess it was getting sucked up into the pick up and dropped, that would explain why the sound was so random an inconsistent verses a slipped valve moving up and down in sync. And while the oil was cold and thick it didn't move as much as it did when it was hot. Awesome, so I'm satisfied that I found the noise maker, now, WTF is it and where did it come from!?!?!?!

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Do you know what it is made out of?