Alternative to Rod Knock?!

[atomic_hoji]

Throwing this post out there in hopes someone has a clever idea of an alternative to chase versus the unfortunate reality of what is most likely a rod knocking thoka-thoka-thoka as the car idles..

Quick background is that car had pinky, nasty discoloured junk in the oil a while ago. Was in a pinch, so I changed it out with some old 15W40 Shell Rotella T I had sitting on the shelf. Ran that and dumped it within a couple hundred kilometers to clear out the pinky nasty. New, fresh Penzoil 5W30 in it. No discolouration visible in the valve cover, but found it was still appearing on the dipstick a bit. Figured it was leftover and didn't have time to deal with it the past few weeks due to other life things. Noticed after we had a burst of wicked cold weather that the car was noisy at idle. Too busy, ignored it to get through another exam I had this past week. Had to run into work today and when I got home it's very noticeable now. Weather is warm and cold back and forth and I was really hoping as the weather changed it would go away, but with no luck - it's just getting worse..

Tried loosening the serpentine belt to see if it was a pulley driven noise, but no - noise is still there with belt off. Car starts, revs a bit, drops to idle, and thoka-thoka-thoka noise appears..

I've had no experience first hand with rod knock myself, so I'm using the ye olde interweb videos to compare the sound - which while there is a variety of different nasty sounds of rod knock in YouTube videos, they are all eerily close to what I'm hearing. Only other thing I've heard in person that's similar is a 2UZ when it gets a crack in the exhaust manifold - I feel like that's more of a ticka-ticka-ticka though... If it IS the manifold it's all the more reason to chase a long-tube.

Have to limp through to March Break when I've put in to take the week off. Fingers crossed I can find something else to explain the issue; e.g. manifold.. Of course, first step of troubleshooting will be to check the oil for metal. Worst case will be either find another low'ish mileage 2ZR to swap - and flip the Valvematic head or get another ECM for an -FE - or yank it and slam the 1NZ back in..

Fingers crossed you clever folks have some good ideas to chase...
-- Adam