Within a mile of leaving work yesterday afternoon, the check engine light on my 125,000 mile 2003 AP1 came on and my engine started running rough. I immediately pulled over, noticing a loud rattling sound coming from the engine before it stalled at idle. I popped open the hood and checked the oil. Low oil (just past the bottom of the dipstick) and smoke from the dipstick hole. Opening the filler cap revealed much smoke, and when I started pouring in a new quart the oil sizzled a bit. (Engine coolant temperature remained normal through all of this.) I started the engine again, and it idled OK and sounded normal. The ODB2 reader revealed a P1259 code, VTEC Malfunction. No strange noises at idle (no unusual strange noises that is), but as soon as I hit the throttle the deathly rattle continued from somewhere inside the engine. I babied the car 20 mile home, trying to keep revs below 4000 or so and throttle to a minimum. In stop and go traffic, everything appeared normal, but every time I accelerated the rattle continues. It appears to be more related to throttle than engine RPM.

Any ideas what I blew up by not paying attention to my engine oil level? This sounds like a very expensive noise.

 

Sounds like your lack of oil, spun a bearing. Time for Leak down test and compression test.

 

Compression appears good: 225/220/225/225. But the engine is making a sound like a microwave oven carousel off its track – click click CLUNK click CLUNK. I suppose there is no way to know for sure what's going on without taking the head off the engine, but I wonder why a VTEC-specific code was thrown.

 

Any type of rattle noise that sounded like a heat shield?
sounds like a spun bearing. Hopefully you got off lucky and only need a crank refurb and new bearings

 

It threw a VTEC malfunction because you didn't have enough oil pressure. The engine ran low on oil and spun a rod bearing, expensive noises indeed.

 

Concur. It all adds up. Low oil will kill these motors quickly if you vtec. If you vtec with low oil pressure you'll get vtec cel.

Vtec cel, followed by discovering extremely low oil, followed by engine noises, is a classic tale of bad rod bearings.

Thats the bad news. The silver lining though is you might be able to save the motor. If crank isn't scored, you can drop lower pan, remove each rod cap, remove bearings, hand polish crank, replace bearings with proper size (whichever of the various stock sizes each rod was built with). Reassemble.

Key to this repair is finding someone that knows how to hand polish a crank, and is willing to do it with engine still in car. Tbat and NOT CRANKING THE MOTOR until its repaired. You risk going from fixable to boat anchor if you do.

 

if a bearing actually spun or you are hearing sounds because of a worn out bearings, its FAR beyond being able to be polished out... I caught mine when pressure started to drop but WAY before you could hear any abnormal noises or any real damage happening.
It still required turning the crank journals .010" to fully clean it up.

 

OUCH! How far down can to cut into the crank and use oversized bearings? Or is this not possible with an S2000 crank?

 

I'm pretty sure .020" I know ACL only lists it for .010 but i believe they have them for .020. I know a lot of guys say just to drop the pan and replace the con rod bearings and that's what I was going to do until if found out it was my mains. But now after going through it..I would HIGHLY recommend you pull the motor to clean all the shavings out. Only one of my main bearings got down to copper but there was copper debris everywhere, mainly built up in the oil gallies. My rod bearings were not going out, but there was trash all up in them from the mains going out. So it's reasonable to believe it would be the other way around as well.

 

I would not do an in-car repair. Drop the engine, take it apart, clean out all oil passages (oil pump, cooler, etc.), send the crank to a machine shop, mic your parts, i.e. do it right.