high pitched noise. turbo?

while on the highway doing 100km/hr at about 2500rpm on neutral throttle i hear a high pitched noise (i can also get it in 4th at the same rpm). as soon as i go above 2500rpm the noise dissapears and changes to the normal turbo spool noise. i've checked for leaks in the intake but didn't find anything. I've checked for play in the turbo bearings and things seem fine. is this just normal for a nav with a snorkal and i'm just being paranoid? i still have nissan factory warrenty till march 2010 and i'm wondering if i should bring it in for them to have a look at? might have to return egr back to standard but

is it something thats just started? prob wouldnt hurt to get it checked out hey. snorkels normally make a roaring gushing sound which distorts a bit when you have a stick stuck down in it lol...

thanks Bob. i can't really be sure when it started as i've only had the car for a couple of months now and i noticed it somewhere inbetween then and now. maybe it was doing it from when i first got it i don't know

could also be idler or alternator bearings. also the belt can do some weird noises when its starting to wear out.

thanks Tweak. will check those out. how often should the belts be changed?

no idea, when ever they go faulty
on other machines we used to fix the multi-rib belts used to generate static when they started going faulty. makes a cracking noise like bearings are going. unfortunately for us the static used to spike the electronics.

the bearing in the idler setup is open for crap to get in a stuff the bearings. Nissan doesn't supply new bearings so people have got them from else where.

my mate had the same problem and took it into nissan and they said it was because he cut a muffler out of the exhaust. so he got the other one cut out and replaced with a 2.5 inch exhaust and it stoped. it sounded bad like fast moving metal shearing on metal but was just some weird not in the exhaust

Wondered if you found what it was. Mine has a similar high picthed noise, it seems only to be there when accelerating away. or if I am just cruising. I replaced all the belts and was till there. gave it massive spray with CRC and seemed to stop it for a few 1000Klms then came back.

Might be an idea to check the hoses between the turbo and the intake manifold for leaks. They don't always use the best clamps on them, some of the clamps can damage the hose. Soapy water poured over the hose (particularly the ends) while you're giving it a tap on the accelerator might show up the leak.

Probably the be the belt tensioner.

Dave.

I get a slight whistle between 1800 and 2000 rpm recently, sounds like it's coming from the snorkel entry. Seems to disappear when the engine warms up.

only happens when accelerating.......

are you sure it's not the wife?

Dave said:

Probably the be the belt tensioner.

Dave.

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Copy that Dave..... I had this problem a while back. Not a huge job, I took photo's and will get around to the how to one day.......

thanks guys. it still makes the noise 30,000km later and 12 months on. i just figured it was the tensioner. last time i was on the beach it became louder. i checked the compressor wheel for play and all seemed fine. once engine cooled it was back to normal. so yeh most likely tensioner and now that i've noticed Yakka's how to thread below i have no excuse to not replace it.

http://www.navara.asia/d22-engine/5578-zd30-idler-pully-fan-belt-how.html

hehe failing that could be the wife.

I get the same high pitch whistle too, happened soon as I cut the muffler out. Been the same now for somewhere between 20-30000k so not gona worry about it!

felixblack said:

yeh most likely tensioner and now that i've noticed Yakka's how to thread below i have no excuse to not replace it.

http://www.navara.asia/d22-engine/5578-zd30-idler-pully-fan-belt-how.html

hehe failing that could be the wife.

Click to expand...

If it is the latter... race tape should fix it!!

I have a high pitched noise under load, sounds to me like an electrical chatter or if you could imagine a cricket on steroids, any thoughts would be appreciated.

check for exhaust leak, it can give high pitch crack/whistle type noise. egr pipe is known to crack at turbo end.

I'd go exhaust leak before turbo boost leak given that it's not a constant whistle but a high frequency vibratory sound - definitely look around the EGR pipe for soot marks.