I'm a car noob, and have never heard "knock" before, but I would guess this is it. I'm scared to death its something serious. Here's my story:
Filled up with gas at 4:30pm at SpeedWay. Drove about 1.5 hours from Lansing to Mt Pleasant doing about 90 or so MPH (so 4k rpm's steady the whole way). Stop and eat at Bennigans. Start driving north again for 1.5 more hours until I get to Gaylord. Stoping at the stop sign at the end of hte off-ramp, I let the RPM's drop to idle and there is a LOUD ticking/knocking noise from my engine bay, I mean it sounds REALLY bad. But the engine feels fine to drive. No loss of power, and the ticking/knocking goes away above 2500 RPM's, it completely smooths out and sounds perfect.
Anyway, I'm freaking. So I get it up to Boyne Mountain, about 15 minutes later, and turn the car off for a few seconds while I run in to take a piss, and look under the hood. Everything passes visual inspection, oil level normal. Start the car up, and now it only knocks/ticks below 2000 RPM. Ok, so I need to get home, and at highway speeds RPM's are above 2000 anyway, so I figure I'll be fine. I get it home, turn the engine off, go inside, go back outside, start her up, and now she only does it below 1700 RPM. wtf?
I tried listening to where the knock is coming from, seems to be under the front valve cover from best I can tell, its just so freakin loud.
Guys, I'm a noob, have no idea what this could be, and I'm scared sh!tless its a spun bearing or something. I really don't want to dump a grand or more into this engine, I was hoping it'd last another year or two before I have to do that... What could this be?
