i recently started hearing a whirring and a bearing noise from my engine.it whirrs on idle and when i rev it the noise gets higher and as it comes down its sounds like a bearing spinning same as how a supercharger sounds.
i was in second gear at 3500 rpm then shifted to third and went up to 3000 then in neutral and rolled to a red light,thats when i noticed the noise.prior to that i replaced the battery ground.

noise seems to be coming fom the passenger side of the engine around the intake manifold side.

i have a 98 frontier 4cyl ka24de,reason i ask on a 240 forum is that there is many similarities with the engines besides a couple internal/extenal parts.

im totally stumped on this problem and no one so far has helped me.

 

if you could record the sound for us we'd be able to better assist you. otherwise it would be more of a guess without any real certainty.

 

I know the sound your talking about man i have the same problem ill record the sound youmean if you need because ive been going crazy trying to figure that out. It really doesnt affect driving but its annoying in my opinion. Ill try to record that sound and get it up asap for you if you need.

 

its your water pumps.. haha sounds like a lil turbo

 

not sure if the frontier comes in a manual tranny. but i had the same issue with my input shaft bearing being shot. making a clanking/whirring/whinning sound... it might be that.

 

does that mean the water pump is bad if its soundin like a turbo??i have that same sound on my 13

 

The water pump is bad when it leaks. Until then it's just annoying.

 

Power steering pump will to that too.