Resonating Noise

[Norquist]

I've just started noticing a noise under the hood. I kind of think it's turbo related but my with my inexperience in diesels / turbos who knows?

With the truck idleing in neutral it sounds fine, put it in gear and you can hear this sound, it's really hard to describe though. Almost RPM related.

I've found that by moving (pushing slightly) on the air intake hose the sound dimishes, let go it comes back. Also, when I push on the the very end of the tail pipe it seems to go away too. This is why I think turbo related.(this is all done with it in gear emergency brake on).

It also goes away when you just start to accelerate. I don't really want to take it to the dealer for something like this unless it may be a possible critical failure even though it's still under warranty.

Anybody experience this?

I guess it could be best described as a "vibrating noise" but seem to stop as described above

[ 04-26-2002: Message edited by: Norquist ]</p>

[hoot]

What year truck?

The turbo typically does not make any sound at idle.

Can you describe the sound? High pitch? Low pitch? Whirring?

My truck makes a hydraulic pump whine that comes from the tranny. It's normal as far as I know. Has been at the same level for 26,000 miles.

[Norquist]

It's a 2001 with 23K on it. Allison transmission.I say resonating due to it's like the old cherry bomb mufflers I used to run as a kid. It's a annoying Humm and like I said it goes away when you start to accelerate but like sitting at a stop light it bothers me.

A band aid fix would probably slightly raise or lower idle RPM??