Spent a few hours working with my mechanic (Michael) today. Had high hopes for it being the flexplate, being that once he separated the TC from the flexplate, the flexplate was wobbling something good...probably about a 1/4". But after closer inspection, it wasn't hitting anything, and not the cause of the sound; just bent apparently. And whomever installed the motor had a personal aversion to tightening bolts. Michael also discovered that the harmonic balancer had some play in it (~1mm) and it was discovered that its bolt was perfectly loose...we removed it by hand.
So after listening more closely (with and w/o a stethoscope), we determined the clacking sound was louder on the driver's side, and does sound like it's coming from inside the motor near the top, and not the TC/flexplate area. In taking off the that valve cover, Michael noticed that there didn't appear to be enough oil in the "bed" (bottom, galley?). And the front-most valves area looked especially low...almost dry. So we ran it and though the video (see link below) shows some from all pushrods, when we first started it, next to none came out of the two front-most pushrods. Michael says that there should be better flow. (see attached photo) Should they spurt oil at idle? I think the center two pushrods spit up a little during one of the starts when the rpms were higher. Note: Oil pressure light on dash went off immediately upon cranking, even before it fired up.
https://www.youtube.com/watch?v=Eqz7U6h0TbU
So he (and his shop neighbor, whom also heard the noise) suggested it might be a piston rod that wasn't tightened properly to the crank. Our thinking is that the rod is carrying the noise up through that piston, having it sound louder on that side.
I'm close to making the decision to have the car transported to Nick Michale in Phoenix to have him repair/rebuild it. He's quoted me $1,000 for the r&r, and between $1,500 and $3K depending on what he finds, damage-wise. Nick says they've rebuilt about 600 motors, so while I could possibly have it done cheaper, having it blueprinted and assembled by a TR motor Guru is appealing.
But first...I'm chewing on the idea of having Michael pull the oil pan to see if anything is revealed. I have a vision of it indeed being a loose rod (or bad bearings?), along with little other damage seen and chips/debris free oil in the pan and filter. It might be worth the $150-200 Michael will charge for pulling the pan. If so, it sure would be nice to fix the problem via the pan!
Qualified feedback is welcome. Of course there's also the question of the improper oiling. If it was a rod, would that cause the associated pushrod to not push up enough oil up top?
Remove the fan belt. Grab the crank pull and slightly turn it back and fourth. Watch the flywheel.
Discovering that the harmonic balancer bolt was loose, after tightening it, we wanted to see what was causing the flexplate wobblation. So he rotated the motor via the HB bolt as I watched the flexplate turn. And eh...am I mistaken, or is there little possibility that it would run "fine" (like it does), with the exception of the noise if the crank shaft was cracked in half?
