I have not spent enough time in other LBZ's to know if it's common, but my engine has a very distinct whine to it above 2k RPM, it almost sounds like a high pitch power steering pump. Initially I thought it was just the Allison, but if I'm coasting in N and play with the throttle the whine is still there and varies with the throttle position. What are everyone's thoughts on this?

Thank you,
Eric

turbo

turbo

x2

If I drive mine with the radio off I can hear it at even lower RPM's, with the truck cold its even louder

Come on guys I am not that dense, ASE Master Tech here, but for the dark side (Toyota) this is not a turbo whistle. A very distinct high pitch whine that is more present when cold like Doc said.

my bad ASE Master Tech, as am i and i work on them every day. if its not the turbo than i would have to hear it. I never said you were dense.

Maybe a ;) should have been inserted after dense, going from Toyota's to my truck even the slightest abnormal noise I pick up on.

Yours might be different then mine. I know mines the turbo b/c of how it dies down when I let off the throttle, just how it 'spools down'

I do know when I first start to drive in the morning I can here my fan clutch is locked. The fan gets really noisy around 2k rpm's. Once I get to the end of the street the clutch unlocks and it gets quieter.

stupid ? but is it radio interference. also just because it is in nuetral does not mean it is not the tranny. even in nuetral there are still parts moving in tha trans. other wise how would a pto work off of the trans in nuetral.

Not radio interference, it's definitely coming from the engine bay area. I'm thinking it's got to be power steering pump or high pressure fuel pump related. True on the trans, but the majority of the components are not rotating and I've heard plenty of noisy Allison's.

I am more curious if anyone else has noticed it, mind you on a truck with an after-market exhaust you're probably not going to hear it.

i have driven lots of stock dmaxs. maybe power steering but i have never heard the injection pump make noise. just my .02

Could this be the alternator whining. A bad diode would cause a whine.

Let my dad borrow my truck in the snow and he left it on 4wd I had the same sound. It was my transfer case whining. Exactly like you said only about 2k and above. Popped is back into 2wd and the whine was gone. Hope this helps!

-Kyle

Yes sir my t-case whines like hell too, I am miffed about the noise. I need to go for a ride in a stock LBZ.

so what do you think it sounds like...transfer case?

Nope it's not the t-case that's even louder than this whine. The t-case whine is only on deceleration when in 4x4.