Rod knock? Hammering Valvetrain?

[VAnoobie]

My car started smoking heavily one day after a test drive after a suspension tuning i did. I was revving the the engine from engine bay by the throttle body to gather info on the smoking and see what I can gather. But in doing so, around 3-4k (my guess as I wasnt in the car) I started hearing a knock. Not a tap, a very distinct Knock. Only in that rpm range. Not higher, not lower. My hand was on the engine revving it and I could feel the engine knock in my hand when I'd hear it. It wasnt jerking out of my hand or felt like it was going to break, but I def felt the knock in my hand and to me that felt too hard to be anything in the valvetrain but I can't help to think of putting two and two together.

So after that, I slumped my head and was pretty much assured i spun a bearing and had rod knock. So I lift my car, start ripping stuff apart to get to my crank. I took the oil pan off and out and could see the bottom of my rods somewhat. Then took the pick up tube and bottom shield baffle out and could see a lot better and touch them now.

Now for my confusion: NONE of rods budged at the bearing where it meets the crank. They all had side to side play so I doubt that they are so tight Im not able to move them by hand. I had a big socket wrench rotating the crank. Rotated the crank all the way around touching all the connector rod bearing sites and I couldnt get any of the to show me any bearing clearance play at all. I even tried getting an extension, and prying on the nuts of the rod ends and pulling on the wrench at the socket (probably not good practice but eh... choose safe spots) trying to see ANY movement and nothing. I ran a strong magnet through the oil and pan and picked up very minimal particles and those particles were very small and not flakelike. No metal flakes in the oil screen at all.

So I'm at a loss. I was pretty sure it was rod bearing gone but now theres things that show that might not be it. but before I start taking the more delicate precision parts out for no reason, I guess I'd ask some pro guys, since im a newbie.

Could the play be so microscopic that I wouldnt feel or see it but still rod knock that hard? Is it something else? I dunno of anything that can knock hard enough to clearly feel it through your hand. Could it actually be the valvetrain? Timing belt? sticking valves? All the videos that I seen on youtube with similar knocking sound ended up being a rod bearing gone, but they always had some clear play at the rod bearing site so I don't know whats going on.

Not sure if this was the right section for these questions. kinda new here.

[shorod]

What type of car are you working on and what engine does it have? Maybe there are some common issues that knowing the vehicle details will help identify.

Are you absolutely positive the noise you were hearing and feeling was not a misfire?

-Rod

[DeltaP]

It'd be hard to feel, lets say .010" bearing clearance at the crank pushing and pulling an installed rod/piston in a cylinder. Possible wrist pin wear excessive. Year,make,engine and mileage,prior work on engine info would help.

[VAnoobie]

It's a 2000 prelude with 2.2L 4-cyl H22a4 vtec Engine. I doubt missfire. But it does make me think of detonation. But I do always fill up with top octane fuel. I'm not sure what detonation is like on my engine. Engine had no stuttering/pausing/hesitating or anything like that like missfiring causes. Smooth revs with just a clearly audible metallic knock sound added around 3-4k rpm. Almost like an off/on switch. Its either audible or it isnt at all. Doesnt change in knock strength or pitch. Its fairly constant.

I've asked in forums dedicated to Honda/Preludes with not much answers or similarities. Others that have heard the rod knock sound, have found play in their rod bearings and sometimes flakes in the oil and other tale tell signs that i'm not finding with mine.

[kcducttaper]

What color was the smoke?

[DeltaP]

You say it's a metallic knock. That would separate it from pre ignition. Can you hear it at an idle? Left long enough like that and you will be able to feel it pushing and shoving on the rod from below. That will be the death knoll of the engine. If it does it at an idle raise the idle some,(1000 rpm), and shut the engine off holding it there. If it "klunks" as the engine dies then its a wrist pin ,(piston pin for all younger guys). The pin that connects the rod to the piston. HTH

[VAnoobie]

Color of smoke was white. Maybe some bluish tint. Hard to tell with the lighting. Like i mentioned, I dont hear it at idle. only at like 3krpm. If I go a little lower or a little higher, it goes away. My car has a pretty noisy valvetrain which is normal for these engines and the knock is pretty distinct from that.

I've already taken the engine apart a bit so I can't start it. I've thought about wrist pin wear but I don't really know what that entails. Its no spun bearing, but what can happen running a car like that aside from noise? Is it damaging to other components?

[Crvett69]

might also be a main bearing knock. did you take the valve cover off and check for possible damage up there? also there should not be metal of any type in the oil or oil pan

[DeltaP]

You can cut open the oil filter checking for metal caught in the media.