Engine Knock

I have a 07 Diesel D40 and have noticed lately that i can here a knock while sitting at the lights etc. It is pronounced knock knock knock then a short interval and knock knock then repeats. It does not appear to increase speed when revs increased but is harder to hear with engine noise.
I have listened with a long scredriver to my ear and it appears to come from a solenoid that is at the junction of the rubber pipe and the alum inlet manifold. i.e. air inlet.

Does anybody have any idea what it could be? The engine is fine, same power behaving normally.

Ideas thanks.

Hi roscoe07, I have a 2010 ST and had the exact noise you describe and your on the money that its a solenoid! For mine it was the VNT solenoid to do with the turbo. Nissan advised that it was a known problem recorded on their system and had a specific fix to do with the way its mounted. Had to order some parts from Melbourne and they completley replaced mine including the solenoid under warranty. It was there for about 45mins. Nissan were a little unclear as to weather the actual solenoid was playing up or it was just the mounting and I didnt notice any difference in performance after it was fixed. I do have the EGR block mod and initially took it out when I noticed the knocking and found that the noise was quite less noticable with it out! Anyway put the EGR plate back in & havnt had a problem since Nissan fixed it.

Hi Exhiluxowner, Unfortunately mine is out of warranty. The VNT solenoid. Is it front drivers side of engine?

I thought that you may have been out of warranty but maybe you should speak to Nissan anyway incase they see it differently as in a fault they may honour etc..They didnt indicate that the problem was detrimental to the engine in anyway either. The noise on mine was near the turbo intake on drivers side and actually i could hear it if i opened the air filter box and listened through that with the engine running.

Sorry correction - it was on the front passenger side in mine!

Thanks I will check how you describe but the noise i hear is pretty definitely coming from the alum housing front right at the last point of the ducting as air flows in to the manifold.