Engine Noise only under load mid range rpm

[teno45]

Hi Guys,

over the last couple weeks the troll has started making an interesting noise. sounds something similar to whistling and humming at the same time.

The troll is a 2008 ST 3.0L CRD. had a service done about 55000kms, now has done just over 57000.

Usually starts during acceleration, around 2200-2800rpm, anywhere from 40-110k/h.

If you go over about 3000rpm it stops. When you come back down, it usually doesn't start right away.

Holding RPM steady, the noise usually goes away after a while. sometimes only a minute, sometimes ten.

Seems to be while engine is warm, not when cold.

If put into neutral whilst making the noise, and trying to hold rpm constant, noise goes away, but I'm struggling to hold the rpm steady when dropping out of gear. (usually goes too high or too low).

Noise seems to increase with RPM (til 3k rpm), but not with speed.

Any ideas on what it could be or where to look?

Thanks for your help.

Teno


http://youtu.be/hY6chekhae4

PS. video doesn't show anything, just the audio. The reason the noise pulses, is me varying the throttle. Was the only way to make it noticeable in the video.

[Ben-e-boy]

Gday

Check for leaks in you air intake, I think a whistling sound is the sign for a leak, someone would have to correct me if im wrong

[nissannewby]

It could be an exhaust leak, an intake leak you may possibly see a slight drop in boost. Get the ole soapy water out and spray it on these joints while someone holds it at revs for you.

[Killametre]

Sounds like a boost leak check all your intake clamps and hoses on boost side. The soapy water test would not be conclusive unless you pressurise your intake with compressed air as you will find there would be very little pressure there when free reving and your fan would most likely blow the soapy water away

[Robo]

Had a broken vacume diaphragm years back and that made a sound like/similar to what you describe.
just looked at vid no sound at my end, just your nice clean dash

sounded a bit like one of those party whistles that rolled out extending.

[teno45]

Thanks for the ideas guys. Will have to get onto it over the weekend, working long hours this week just wont give me time!



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[johno90]

Could be something like common bt50 problem, soleniods that control vacume lines etc get dirt in them and close halfway creating a whistling noise that surprisingly loud for such a small object.

[Nixon]

Hi - see earlier thread on "Destroyed Flex Plate /Ring Gear on GU auto" . Its actually a 2006 ST Auto. When I asked the mechanic on whether there should have been any warning signs prior to my issue, he asked if I had heard any humming noises. I said no but your thread reminded me of an ongoing issue of a "vibration type noise" that I got (I thought that it may have been something loose behind the dash ) when the RPM got below or above a ceratin threshold, almost exaclty the figures and Km/h that you are experiencing. I am now wondering whether the flex plate was trying to tell me something??? Unfortunatley I haven't my vehicle back yet so I cant check whether the noise has gone.

[teno45]

Could be something like common bt50 problem, soleniods that control vacume lines etc get dirt in them and close halfway creating a whistling noise that surprisingly loud for such a small object.

Thanks for the idea mate, will have a look over the engine over the weekend, might look into that solenoid.


Hi - see earlier thread on "Destroyed Flex Plate /Ring Gear on GU auto" . Its actually a 2006 ST Auto. When I asked the mechanic on whether there should have been any warning signs prior to my issue, he asked if I had heard any humming noises. I said no but your thread reminded me of an ongoing issue of a "vibration type noise" that I got (I thought that it may have been something loose behind the dash ) when the RPM got below or above a ceratin threshold, almost exaclty the figures and Km/h that you are experiencing. I am now wondering whether the flex plate was trying to tell me something??? Unfortunatley I haven't my vehicle back yet so I cant check whether the noise has gone.

Wow, that sucks mate. sorry to hear that! Hope thats not my problem. Will checkout the things mentioned above, if it doesnt go away, might have to take it to "someone in the know..."

[brooks729]

Hi, I have a 2008 St with 98000kms, I have exactly the same anoying buzzing sound as you. It is more noticeable under load and seems to be when the torque converter is not locked in. Has anyone worked out what it might be yet?

[Sir Roofy]

sounds like a manifold gasket leaking, get a peace of
hose and have listen

[k.read13]

Was anyone able to solve this? We have the same problem with our 2012 GU only done 30,000km. There has been a buzzing noise for the last 20,000km and the Nissan mechanics don't know what it is. They have replaced the turbo and the noise is still there.

[Hodge]

The threads of this exact same sound keep popping up and all are CRD's. Just listened to your video and mine is identical!! I'll actually record mine tomorrow. So far the most plausible answers point to a exhaust manifold warped, EGR pipe warped/cracked.
Mine is exactly in-line with the turbo spooling up / boost in terms of sound. As I'm watching my boost gauge, the more numbers it shows the louder the noise it.

Here is my thread about it.
http://www.nissanpatrol.com.au/forums/showthread.php?22050-3L-CRD-Turbo-busted-or-leaking