Boost leak ?

[christopherL]

Hi I have a 2011 nissan pathfinder which under boost sounds like it has a boost leak it has a variable vein turbo so there is no waste gate solenoid or lines to leak. the noise is constant under full boost but the noise gets a little quieter as it changes up gear probably due to boost drop for a second because of it being a variable vein turbo. It has the normal turbo whistle but this is something else and is loud. I have had the turbo rebuild because I thought it was the issue but the noise remains so my question is this a normal noise for a the variable vein turbo model or is there a common leak point. I can't see and oily leaks on the intake or line

 

[Old.Tony]

Hey @christopherL welcome to the forum!

It's possible that it's an EGR leak too. The gold tube that runs around the front of the YD25 motor can develop a leak and it will make sounds. I had a screechy sound coming from mine once, it was actually the gasket between the exhaust manifold and the turbocharger, but I don't suspect that for yours since the turbo would have come out for the rebuild and a bad gasket would have been noticed.

Other sources of noisy screeching under load: alternator pulley (back off the tension of the belt, and see if the pulley is firmly attached to the alternator). Check the radiator fan for cracked blades - if they are, you might notice some gouging of the back of the radiator. You'd want to fix this sooner rather than later!

 

[christopherL]

Hey @christopherL welcome to the forum!

It's possible that it's an EGR leak too. The gold tube that runs around the front of the YD25 motor can develop a leak and it will make sounds. I had a screechy sound coming from mine once, it was actually the gasket between the exhaust manifold and the turbocharger, but I don't suspect that for yours since the turbo would have come out for the rebuild and a bad gasket would have been noticed.

Other sources of noisy screeching under load: alternator pulley (back off the tension of the belt, and see if the pulley is firmly attached to the alternator). Check the radiator fan for cracked blades - if they are, you might notice some gouging of the back of the radiator. You'd want to fix this sooner rather than later!

 

[christopherL]

I have pulled the EGR pipe off and resealed it there was a crack In the fan shroud which I have now repaired. I installed a new alternator a couple months ago which made no difference to the sound. I have noticed if I change down so the engine revs out it will make this sound too and when it happens under load its around the 2500rpm range

 

[Old.Tony]

I have pulled the EGR pipe off and resealed it there was a crack In the fan shroud which I have now repaired. I installed a new alternator a couple months ago which made no difference to the sound. I have noticed if I change down so the engine revs out it will make this sound too and when it happens under load its around the 2500rpm range

Want to have a look around the turbocharger/exhaust manifold for black soot?