Trying to keep this short and sweet. Civic was just given to me so this is a new venture for me. Normally its V8 engines I work with.

2000 Honda Civic EX, recently rebuilt the D16Y8 engine and installed few weeks ago. Been having a weird metal rapping noise that almost sounds like a rod knock but its from top part of engine almost inside head near #1 and #2 cyl. When cold its quiet as a church mouse. As it gets hot the noise starts up on idle with NO LOAD. Rev the motor and it stops until RPMs drop. Turn on AC compressor and it pretty much goes away. Engine has less then 60 miles and about an hour of idling.

Work completed on rebuilt engine:
Block was bored/honed .50 over
New aftermarket .50 pistons (stock design) and rings (clocked correctly)
New aftermarket rod and main bearings (std), measured .0017, .0016, .0015, and .0015 for rods
New aftermarket main bearings (, meaasured within specs on loose side
Head milled and valve job with new guides
Inspected and replaced 1 lost motion assembly since it didnt have smooth travel
Honda OEM head gasket
New OEM timing built, wp, idler and checked tension 2 times
Checked and adjusted valve lash 3 separate times with each time going little tighter and now at .007 and .009
Pulled the oil pan off yesterday and inspected each rod bearing noticed no signs of wear
No shavings of metal in oil pan (just a small milky stream but thats normal after a fresh rebuild)
Pulled off all accessory belts to see if bearing was bad but no dice
Checked make sure exhaust did not have leak and was not rubbing on oilpan

Things I havent checked yet:
Camshaft lobes
Piston to valve clearance (haven't even pulled the head back off yet, would think that distance would be fine on stock motor with only 1 mill performed)

Im kinda gettin frustrated with this engine as it should be factory new and operating like one. Machine shop did good work. I followed ever step carefully using factory manual and took my time. I do not want to pull this head off but if i must.....my next step is pulling rocker assembly out and inspecting rockers and the camshaft. Anything else I should check?

I coulda got a B16 for the price i have invested in this Y8...

 

Noise coming from head but no mention of head and camshaft oil clearances, end-play, runout, and oil control orifice.

 

You also mentioned only replacing 1 LMA. Could be after install one of the 3 old ones started binding.

 

I can press down on all 4 and no binding. I did thoroughly clean and check each one. I have another head I can scavenge from if needed. I'll check again though

 

Yeah that will be a good logical next step also. I have all the clearances printed out. You'd think the machine shop would check that when I brought the head in, but I didn't specify...

I have the original y8 engine that a rod exited out the oil pan and it has a head but the camshaft 3rd bearing race is trashed unfortunately. I couldn't rebuild this engine so I bought a used one and that is the one I rebuilt. The last owner went 2 years (24k miles)with no oil change before it destructed. I mean Hondas can run forever, but you gotta follow maintenance...

 

Never assume...always tell them what you want done.

 

Over the weekend pulled the rocker assembly out and cam and inspected. Cam lobes looked great, journals looked good. Camshaft end play was about .4mm which is within service limit. Rocker arm surfaces looked good. VTEC pistons moved smoothly in the rocker bores. Put all back together and even activated vtec solenoid to see if any difference but none other then at idle the engine wanted to die.

Dont get it. At idle with no AC on and its hot it sounds like a diesel. Turn AC on and it goes way. Rev it and you can hear it when RPM's come back down only. Any other ideas?

 

This was solved by the way...machine shop sent block off to get bored and they bored the block way to large for the pistons. Some machine shops really dont take into consideration the tighter tolerances of these engines...

 

So, piston slap from sloppy machine work.

Thanks for coming back and sharing what the problem turned out to be.