[Rickyshucks]

Hi All,

I have a n52 w/ headers, 3stage IM, straight piped exhaust + magnaflow muffler, and STAGEFP Stage 2 TUNE w/ burble.

My car was about to go in for exhaust repair after getting rear ended and my brother revved the car to get some pops.... Well now, this sound is coming from the head of the engine... Car is about 270,000 KM.

https://streamable.com/dvu8sd

I plan to bring it to my mechanic next week for a diagnosis but thought I'd try an get other's opinions on what it could be. Lifters? I have no clue.

Thanks in advanced.

[Rickyshucks]

Maybe even a dislodged DISA VALVE pin? *facepalm*

[E92William]

That almost sounds like a bad pulley to me. What does it sound like with the oil fill cap off? First thing I'd do in this situation is take off the serpentine belt and see if it continues to make the noise. If you have all these mods done then you surely have inpa and can give your disas a quick test. Should be a sharp and quick sound but I doubt it's that.

[bluewater328]

That doesn't sound like a bad DISA unless enough parts broke off and its freewheeling. In which case, that's still not gonna be your real problem at this point. I'm not sure, but pulley sounds more likely -- but I'd also assume you could sound isolate if that were the case.

[JonOhh]

It sure sounds airy to me on the video, you're 100% sure there's no exhaust leaks on the headers?

But otherwise,

If it's directly coupled to rpm and you want to check if it's any of the accessory drive pulleys, you can do this:

Use a paint pen to put a dot on each pulley that will be easily visible as it's rotating. Preferably white so it's the easiest to see, but be sure to avoid the belt face of the pulley entirely.

Start the engine and let the rpm stabilize, and then record the engine running using the slow motion video feature on your phone (I assume you have this). Go from pulley to pulley for a few seconds.

You should then be able to tell if the sound is correlating exactly with the rpm of a particular pulley, when you watch the video. Also do the crank pulley, even though it won't be the cause of the noise, you can potentially help use that to determine whether it happens once per crankshaft revolution, once per two crankshaft revolutions, and so on- this can point you in the right direction of a valvetrain or bottom end issue.

It is possible for bearings to fail in such a way that the noise they make isn't exactly once per revolution, because the bearing race spins slower than the outside, but I've had this method work very well on my X1/9 and 2000 Impala. It's worth the 10 minutes regardless.