bitNine

Hey all, I've encountered my first problem with my 2011 G37. Just before hitting the 11k miles mark, I took a trip up the mountains to go snowboarding (about a 90 minute drive) one morning about 10 days ago, and when I arrived I got out of the car and was greeted by a very loud knocking noise coming from the engine that would go away just by giving it a tiny tiny bit of gas, but would come back as soon as it went back to full idle. I immediately pulled out my phone, and took this video:

G37 Knock - YouTube

I first noticed this noise when the car had less than 3k on it, but I noticed it from the inside. My favorite thing about the car, when I first got it, was how quiet it was inside at idle. Then I noticed that when the engine was really hot, I would hear a slight knocking noise from inside, but only at idle. It was noticeable the last time I took it in for service, but I didn't think they would take me seriously on it. After the oil change, the noise was gone, and didn't reappear until a few weeks later. Seems to be oil viscosity related since this noise is only prevalent when the engine is hot... not hot like my 8 mile drive to work... more like 90 freeway miles in CO mountains hot.

I am taking the car in on Friday for its 11,250 mi service, and they are going to take a look at this, but does anyone have any idea what this noise is? Other than this problem, I've not had any issues with the car.

P Casey

iTrader: (13)

Do you leak oil at all?

bitNine

Nope, I would notice a single drop of oil on my garage floor. I can almost eat off of it, lol. I will admit, I have not checked the oil level since the last change. I'm lazy with this car because it's new, I have the full maintenance, and I have 3 other older vehicles that get the majority of the attention.

Weiboy718

iTrader: (10)

Did you check your oil level yet? Check it out real quick

Weiboy718

iTrader: (10)

It may be the VVEL ticking also.

P Casey

iTrader: (13)

Yup, or I was thinking oil pressure/level

bythabay

iTrader: (2)

What kind of oil you using? I would stay away from conventional, as the vvel shears it out of grade, especially given the heat.

biron

iTrader: (1)

I have that same sound too but my car has 40k miles. Haven't done my oil routine yet, so I'm guessing it might have to do with the oil also.

JSolo

iTrader: (14)

To the OP, how many miles since the last oil change? What oil you using?

bitNine

Oil is whatever the dealer is putting in there since I have the maintenance package. I think the last oil change was right about 7500 miles. I've been sticking to the book on that. I will run out and check the oil here in a bit.

t-bone1924

VVEL noise---no doubt at all. Have TSB done and use ester oil if the noise bothers you.

t-bone1924

To convince yourself that it is the VVEL noise, next time it happens (mostly after aggressive driving and only at idle) shut off the engine and then immediately restart it. I bet the noise immediately goes away! The reason is that the VVEL cam assembly resets after engine shutdown.

JSolo

iTrader: (14)

Why the noise in the first place, and why only on the single bank?

t-bone1924

Good question! Just guessing but probably has something to do with the direction of the engine rotation in relation to the valve train position, thus only affecting the driver side valve train.

t-bone1924

Oh, and on why the noise is happening?

The VVEL design allows the valve assembly to lift in relation to the acceleration of the engine--that is why we get such good smooth acceleration with reduced gas consumption. The problem is that under aggressive driving, the special coating on the cam gets starved for lube and it stays in the extreme lifted position even after returning to idle speed thus causing the knocking. Somehow the TSB tells the valve train servo mechanism to reset properly at idle.

(mainly BS I just made up....