dyno

I hear a noise coming from left engine's bank when accelerating from idle: seems like valves are too loose... but shouldn't they have to be automatically fixed by our hydraulic lifters? did u ever experienced this?

it is something like knocking noise but of a lower tone level.

1- only when the engine is very hot. I first heard it when back home after various pulls because I was trying to test the gain from TB install.
2- hear both at idle and grows if accelerating. When high revs, don't hear anymore.
3- left bank only
4- sounds like valves are not correctly tightened .. it is the same noise I have in my bike and when asked the mechanic he told me it was that reason and no need to worry ... but for the car, I thought our valves should be self regulating!
5- in any case, engine works well, except torque limitiation when above 5000-5500rpm

- couldn't be something wrong with hydraulic lifters?

one mechanic also told about the possibility of an aux pulley ...
Tomorrow will arrive the chief mech and will see. hope the mech that installed the Tb didn't do anything wrong.
Unfortunately I didn't pay attention till 2 weeks ago when I still had the stock pulley installed and no mods.
I think at valves because it's strange that the sound seems to come clearly from the left bank!

dyno

.. not clear what I meant or anybody experienced the same thing?

sanfran

Did you ever get this noise diagnosed?

I have heard the same noise on a car I'd like to buy and would like to know what it is.

How many miles did your car have when this started?

Was it just the pulley?

dyno

yes, we listened to it when I was at the Service and even if it was unclear also for them to understand what it was, the mechanic suggested to replace the belt tensioner (compressor belt). and it disappeared.
I had about 23-25 Kmiles.

that worn bearing made indeed a very scaring sound !

bobgodd

I should try that because my car is making the same sound!

Exotic-metal55

Yes pulley noise can be loud! I replaced my idler pulley with this ASP model but need to have them build the tensioner next..

vinnyz

check the front on drivers side behind ur headlight its a recirculation pump it makes that noise and if u put ur hand on it u can feel it going with the sound .. i hear it all the time , 1st time i heard it i took to dealership and told me what it was ... its a dark colored hose but listen and u will find it then place ur hand on it , but it does sound like a ticking noise

dacls63amg

Could be a busted weld on your headers or down pipe. I know when those welds break or crack they make a loud popping/ ticking sound. Just an idea.

dyno

interesting to see how this thing finally found its spectators ..

I had the belt tensioner replaced under warranty by the dealer and took home my old piece. ( I guess they didn't replace the idler pulley, thoug).

I just now went to look for my old part inside the big box of all my toys, looked a bit more attentively at it (which I hadn't done till now) and took a pic




just to make things definately clear, I was talking of the LEFT bank (passenger side)

Having it at hand is now clear and sure that it was because of it being worn.

If you want to check the state of yours, just loosen your compressor belt so that you can take the tensioner pully with your hand.
then, try to mobve it quickly up and down.
if you hear that knocking noise ... it is it !