My poor xB's too young to be sick! Chuck has less than 40k miles on him, but I've started hearing this metallic rattling from the engine. The rattle frequency increases with higher revs, so I"m pretty sure it's the engine and not something else. I might be paranoid, but I also think there's a little too much noise at idle. It sounds like a constant 'tick tick tick' noise.

Help! What could it be?

 

that is what i call 4 banger knock it is normal and nothing to worry about from what i have read. my last 4 cars have been 4 bangers and they all did this

 

What weight oil are you using? My xB made noticeably more valvetrain noise (ticking like you describe) on 5w-20 after it warmed up. I compromise and use 2 quarts each of 5w-30 and 5w-20 of the same brand/type oil and it's a little quieter.

You didn't say it was running badly but I'd also pull the plugs and see if there were any differences in their condition. Replace them if you haven't yet.

 

Your sound description sounds more like the tick sound of the fuel injectors. I would not worry about it. It's a Toyota so as long as the oil gets changed regularly no worries.