UH-OH, M113 E55 knock after valve cover gasket fix

[X5papa]

Hello, figure I would post for the experts to point me in a general direction.
2003 E55K, 105k miles

The valve cover gasket was leaking on one side so I pulled both sides and replaced them. I noticed a large piece of dry flat gasket material (2.5x1.5) fell off and sat on the side of the timing chain. I carefully tried to retrieve it but it decided to jump to the bottom of the timing chain area. Hoping it would sit in the pan and not cause any grief I proceeded.

Shortly after the initial startup I started to get a knock. Never when the engine was cold, only after it warmed up a few minutes. Using a stethoscope it appears to be coming from under the right side (passenger) of the motor. Trying to eliminate things I removed the blower belt and held the pulley to prevent rotation, no dice, knock was still there. I pulled both lifter/rockers assemblies, inspected the springs, lifters, nothing. Everything looked fine. Cleaned it all up hoping cleaning each lifter would make it whole, nope.

Have since changed the oil twice using the Mobile 0-40 and thicker 20-50. No change.

Compression check shows a 2% variance, all 8 cylinders over 157.

So now I am stuck. The knock is at idle to 2k rpm. Car pulls hard to redline, no noise past 2krpm.

Now, I do know I need to replace the valve stem seals as one cylinder showed fouled oil ladden plugs (2 per cylinder on this car). Yes, some smoke. I do not see how that could cause low rpm knock though.

Coolant looks great. No sign of head gasket failure.

Keep in mind the car was flawless prior to this.

I am now thinking the rogue silicone piece has somehow lodged itself restricting the oil flow, perhaps the oil pressure valve. But not sure how it would get past the oil pickup. I believe the timing chain area leads directly to the oil pan-no?

My next step is to remove both oil pans (PITA) and inspect the pressure valve and oil pump for restrictions and inspect the rods. My plan was to sell this car as I need something MPG friendly for a new job, but I am not going to sell a car with a knock. But if I have to rebuild the motor I would likely keep it as a space fun car.

Thoughts? Thanks

[nelbur]

Removing the serpentine belt and starting it briefly will eliminate external things that can knock. If the knock is still there the problem is inside the engine. Regardless, the piece of gasket has to come out as it could likely shut off oil flow if/when it covers the oil intake.