Well, I've torn apart my engine and replaced just about all of the reciprocating parts in the past few months to get rid of knocking sound I have... all to no avail. After tearing apart the head twice, and completely removing the vtec assembly, I've still the noise. I did finally take a stethoscope to engine and started trying to pinpoint it. Here's what I've got.... there's a sound like a hammer hitting an anvil very faintly all over the block, head, intake, and exhaust manifolds. Its not particularly distinct in any of these areas though. Where it is distinct is right on the fuel injectors (which have the same frequency as the tapping, but are out of phase, except the #4. Its the same amplitude as the others though, so I don't think thats the cause), on the steel bracket that attachs to the water pump and the pump itself(where it is very loud along with the sound of rushing water), on the driver's side engine mount, and the timing belt cover right about even with the tensioner pulley.
I've done tons of speculating but I'm hoping someone else has had this problem before, so I can get a definite answer as to whats about to **** itself. I only real parts around there that move are the oil pump, water pump, the tensioner pulley, and the alternator. The noise sounds almost sounds like a bad bearing, but like I said, I'm not terribly sure. Any help would be much appreciated.

 

Is the motor built? It may be rod knock or the tensioner is taking a ****.

 

I just replaced the rods, pistons, intake manifold and fuel rail. The crank was checked for alignment, and all the bearings were filed down to flush. The bottom end is solid as far as I can tell. I had thought it was a rod or something at first, and thats why I ended up doing all of that. The valvetrain is solid as well. There's a few springs that are nearing replacement size, but everything is in tip-top shape, and all of the third followers and lost motion assemblies are removed. I'll be checking the tensioner later today. Thanks

 

Good Luck.

 

Well, its not the water pump or the oil pump, or any of the pulleys as far as we can tell. The noise goes away when you pull the plugs and crank the engine with the starter. I don't know. My buddy and I are about out of options.