Strange knock, help ASAP with the DD

[rutheday]

I have a 04 MT WRX with about 80,000 miles and it is now making a strange sound. In neutral, it makes a fairly consistent knock at around 2,500 RPMs, give or take, after acceleration. So its not moving, blip on the throttle to about 4k and while falling, in neutral, it makes a knock. The engine was relatively cold when this happened. Any thoughts? Let me know if you need any further details as I don't know where to flesh out the details. Thanks!

[mycologist]

Subarus can make all kinds of funny noises and be fine. Mine has had some "piston slap" or possibly valve lifter noise since new when cold and it was quite disturbing at first. If it goes away after it is fully warmed up (15 min.) then ignore it for the rest of the cars long life. This is assuming you have checked your oil. No sense worrying about it either way - if it is going to blow there is nothing you can do to stop it.

There is a very good chance that this example is normal even for an older Subaru with a lot of life left (our 98' sounds almost this bad, but is due for a valve adjustment):

[mycologist]

This is bad on the other hand:

[rutheday]

This is bad on the other hand:

Thank you for your prompt reply. My concern though is that if it an issue with an alignment or something else that needs adjusting before it turns irreparable. It's odd that its at a certain rpm and does not increase with rpms and it can only be heard with pulsing the throttle

[mycologist]

If it doesn't change with RPM, suspect exhaust or something banging around.

[rutheday]

It's coming from the passenger side of the engine bay?