Cody Pereira

Hey all,

Question for the forum - I recently rebuilt a D16Z6 VTEC 5 spd manual with only 115k after it spun a crankshaft bearing (immediately shut down the engine when I saw the light come on.) Fully disassembled the motor and brought it to a reputable engine shop here in Connecticut to tank the block, fly cut the head, hone cylinders, new valves, etc. The crank shaft and journals were inspected to ensure no damage was incurred during the incident. It runs like a top, plenty of power, no oil burning, all is great. The question I have is when accelerating at around 2000 - 2500 rpm, there is an audible faint "knock" coming from the engine bay. This noise does not occur during idle at all, or when revving, only when the engine is under load at that rpm range. I have done the several oil changes since the rebuild (approx 1,600 miles since) and have not seen any "gold" shavings or metallic pieces to indicate there is another bearing issue. Also I have double checked the valve lash clearances to be to shop manual specifications.

I've heard from others that especially the VTEC engines are loud. But just want to put my mind at ease with this freshly rebuild engine. Never heard the sound before, most likely due to a bad muffler which has since been replaced. I can try and record a video this evening; I can replicate the sound by engaging the E-brake, first year and lightly letting off on the clutch to apply the load.

Thanks in advance all.

simike

Sounds like pinging/knocking. Check the timing. It sounds too far advanced.

If you don't have a timing light wait until you are low on gas and put 91/93 octane in and test drive. It should reduce or eliminate the knocking. If the knocking goes away or is reduced timing is likely the issue.

Cody Pereira

Hey there simike, thanks for the reply. I have a timing light and checked the timing recently, it's spot on after a minor adjustment. I will try and put in the higher octane fuel (of course I just filled up yesterday with regular.)

simike

Any luck?

TomCat39

You had the cylinders honed, not bored and honed to over sized pistons?

The hone could put the cylinders out of round right to the edge of spec and cause piston slap. Doesn't stop the car.

I would just drive it like you normally do. If the noise gets louder and worse rather quickly with normal hard driving, then worry. If not continue on as the motor will take quite a beating still before needing a bore and hone and larger pistons and rings.

acmoc

Could be an exhaust leak.
I had a similar sound, but it went away. Reason it went away is the hole in my header was filled by carbon. When I cleaned it out. The nosie came back, then went away again. Had a shop weld the hole.

Since it's only at load. It can be bearings in your alternator, tensioner, water pump, or even something in your tranny.


Things like this it's just better to not worry and let it get worse to make it easier to find.
Sometimes it'll go away.