whine/whistle dont know where from

[BIGMAN73]

Needing info on whine from engine or drivetrain, Whine/whistle began a mounth ago it first started on while driving under a slight load up a hill it would whistle aroung 1800rpm no matter what gear. The noise would last as long as i would keep up that rpm with that load. Now it has moved to going down hills in any gear whenever i let off the gas and it just last a second. I don't think it is 3rd gear like the dealer says. I think it might be in the turbo some where but cant reproduce when sitting in drive way. I do think it is more than just a turbo whine it is loud specially when some one is next to me on the highway. I woud appreciat any info

 

[Alan Reagan]

A couple of things you can try.



First, see if the snorkel is in place between the fender and air filter box. If not, hook it up and see if that reduces the noise. If it does, it's the turbo. 1800 is the point where the turbo is really doing its thing.



Also, there has been some discussion about the heater lines making noise. There is a plastic fitting (from what I understand) in the line that can cause some noise from that area. Mine has made it but it was more of a moan that a whistle/whine.



Make sure the air filter top is latched down completely.



Make sure the boost lines hose clamps are tight.



Make sure the intake manifold bolts are snug (18 ft/lbs) especially the plenum bolts that go through the grid heater.



Check the exhaust manifold bolt torques.

 

[Archive]

Alan... some very good advice.



In reference to the heater hose noise... I had that! I got it fixed under TSB 18-11-99. I believe since he has a '00, it should not be a factor, but you could look up the TSB on fritz's page and check the numbers. The heater noise did sound like a transmission noise, and most dealers were diagnosing it as such... it was happening right as the 6spd was coming out!

 

[Steve M]

If it sounds like a wine glass chirp, that's what it's called. I had it in my '95 auto at around 1750-1800rpm only at a certain throttle position. My '98 5spd didn't do it. A new muffler part number whas suposed to have eliminated it. My new 24v auto has brought this sound back into my life. I beleave it's the exhaust side of the turbo resonating through the exhaust pipe. Ain't it beautiful!!! Of course if that's not what it is and you have something on it's way out, that ain't too pretty. I have a feeling that's what it is though.

 

[Alan Reagan]

Steve, You may be right on the resonation. Mine resonates at 1800-2000 when towing but it's deep. A chirping sound usually indicates a turbo bearing in need of attention. I'd like to hear it. Hard to troubleshoot this one from a distance.

 

[BIGMAN73]

well i appreciat the info It seemed today that it was worse. It starts whisteing once I let off trottle running about 60mph it will whistle untill I put the brakes. It will whistle with rpm down to 1000 rpm. this morning was 72 degrees and rained last night. It seems it does it at any time when I am allowing the motor to slow down the truck

 

[Alan Reagan]

How's the power? The wastegate isn't stuck open is it? I'd check the pressure hoses from the turbo to the intake.

 

[Steve M]

Alan,

Sounds like you're familiar with the whine glass chirp. It's not really a chirp like a squeeky bearing but more of an eerie deep sound. If you ever get the chance to run your finger around the top a real crystal whine glass, you'll see why it's called a whine glass chirp. It rings out a note very similar but of course smaller.

BigMan, I'm at a loss without hearing it. The brakes use a hydraulic boost unit. Boost is down on deceleration. Could be a whine from the transmission or rear end? It could still be the exhaust resonating but it needs to be diagnosed to be sure. Hope it's simple and cheep. Or free!