Long story short my wife's 98 ex (d16y slung a rod through the block. I found a complete d16y8 with a spun bearing. I took the complete bottom end to a machine shop where they turned/polished the crank, turned the rods, decked the block, honed the cylinders, all new bearings, rebuilt the head etc. They assembled the bottom end & I picked it up last Thursday. Thursday night I put the rest of it together, head, intake, water pump, timing belt and so on. Friday morn the car was running great on the lift. Now here's where my issue comes in. When I took the car for a test drive I hear what sounds like a tapping noise coming from the engine when its under a load (will not tap while idling or revving in the driveway) The faster you go the faster the tap gets. I adjusted the valves yesterday and the sound is still there. I thought maybe it was the doughnut gaskets on the exhaust so I replaced all exhaust gaskets including manifold gasket and the noise is still there.. I have no CEL lights and everything works as it should.

My oil pressure is reading 75psi at idle and 95+psi at 3k rpm. I have take the timing belt off and realigned just to be safe 3 times now and its spot on.

I'm all out of ideas of things to check at this point. Anyone have suggestions?



UPDATE: TL:DR Machine shop over honed/bored the cylinders. Had to pull the motor again take it back to them. They Knurled the pistons to make them fit. All tapping is gone under load and the engine runs perfect now.

 

Post head rebuild, did you check valve lash?

 

Yep. Even checked them earlier today when messing with the timing belt. .008 on the intake and .10 on the exhaust it was they check out to

 

Double check your valves

.007-.009 intake
.009-.011 exhaust

When I did mine I adjusted them a few times just to check and verify.

 

I have 3 times now. Even re adjusted even though they were in spec

 

You think it could be transmission related?

 

did you do the valve adjustment before or after you drove around?

 

Not going to rule it out but I can tell you the trans made no noise before the engine swap

I did it the day after I drove it so the engine was cool.

I guess tomorrow I'll put it back on the lift check the tq converter to flex plate bolts and pull the oil pan to double check everything in the bottom end

 

Pulled the oil pan today and checked both main and rod bearings. They look brand new as they should with only 100mi on them. Tomorrow I'm going to change the timing belt tensioner and see if that's my issue. I did notice the timing belt is loose closest to the bumper. Can someone explain the proper way to tighten. I've tried a couple ways which all end with the same result.

 

Have you adjusted the ignition timing to spec?

 

Yep. TDC then waited till fan came on then went off. Jumped the wires under the dash and adjusted the dizzy until the middle red mark was inline with the arrow.

Today I swapped the TB tensioner, verified the timing marks with tdc and reinstalled everything and the tapping is still there. At this point other than pulling the head I've done everything I know to do

 

It could also be bad gas or detonation caused by carbon build up in the cylinders.

Does the CEL work?

 

Shouldn't be any carbon in the cylinders the engine has less than 100mi on it since rebuild. Yea the cel works. I have a p0325 and that's it. I have an aftermarket knock sensor so I figured thats why

 

Should have mentioned P0325 earlier. That's likely the problem. Fix it.

 

Just popped up last night and I've had a couple civics throw the same code with aftermarket ebay knock sensors. How is a P0325 my problem? Car had the same tapping days before the code appeared.

 

Are you really failing to understand the crystal clear link between a "knocking engine" and a "knock" sensor circuit CEL code?

 

Apparently... That's why I'm hear to figure out the tapping noise. If I knew what was tapping I would fix it. I've checked everything but pull the head which I plan to do in the morn

 

You obviously haven't checked everything because your engine continues to knock. The answer to your problem has been and still is staring you in the face - P0325.

Do you have any idea why it's called a knock sensor?

 

Since you're obviously full of answers tell me what's tapping and I'll fix it tomorrow. Then I wont need your definition of a knock sensor.

Like I said above only thing left is to pull the head and see if there is piston to valve clearance issues.

Things I've already checked or replaced:
Timing belt
TB tensioner
Valve adjustment (3 times)
Mechanical and ignition timing
Main bearings & rod bearings
TQ converter bolts
Exhaust gaskets

 

What's the purpose of creating a thread that asks for technical advice if you already have the answer?

 

I can only hope its my answer because at this point I'm ready to throw a match at it

 

Sticky rocker ? https://honda-tech.com/forums/acura-integra-6/ticking-taping-sound-coming-t-belt-side-head-randomly-3154605/ I know it's a SOHC in your case but it can still be a possibility.

 

...

 

My noise is a little different as it only happens under a load. No noise at all idling. The head was checked and cleaned at the machine shop. I will check them before I pull the head though. Thanks for the suggestion

 

Swapped heads today with a spare untouched one I had and the tapping is still there. It starts at exactly 3k rpm. One odd thing I noticed when I had the head off using my hand I was able to wiggle each piston side to side. My feeler gauge only went to .006 So I was unable to if it is within spec. I'm almost positive its not supposed to move like that. Guess I'll call the machine shop tomorrow and see what they say