Rattle Engine Noise under acceleration
 

Hi

(BMW X5 e70 3.0s 150k), there is a rattle noise coming from the engine, under acceleration, between 2000 and 2500 rpm. have already looked at loose stuff but nothing seems to be wrong. the rattle is a bit metallic in nature, is irregular e.g. is not constant.

Any ideas / suggestion of what else to look for?

Thanks,

Vanos problem?

Maybe turbo wastegate rattle?

No turbo there

Fair one. I had my own 3.5d in mind.

need more information,

does it happen only under load or will the rattle occur with the car in park and revving it? can you identify what area of the engine it is coming from? Front? Passenger/driver side? top end? bottom end? Can you post a video? "metallic rattle" is a little vague, hard for people to help with such limited info. Is it a lighter pitched rattle (could indicate outside of motor) or deeper pitched (may indicate inside) Have you done any recent repairs?

For something like this, a video would be great.

Thanks for the replies

Yes, no turbo, is the 3.0si

Rattle happens under load / normal acceleration, it is not 'constant' e.g. from stop, I accelerate and it can last 2-3 seconds, if I replicate the acceleration, may be present a bit more / bit less, but it is not 100% there all the time

I added a bit of oil Today (less than half a quarter), and rattle diminished in loudness (-50% at least). The oil level was 2 'squares" down the max level on the iDrive screen.....

Hmmm... if you're sure the sound was diminished by adding oil then it's definitely inside the engine. Although with that small amount of oil you wouldn't think it would make a difference... Potentially a loose timing chain? timing chain tensioner failure? If I'm not mistaken, these chain tensioners run off oil pressure, with your mileage and depending on your maintenance history, if the tensioner is getting sludged up, it could be making the chain loose. Timing chain guides could be wore out? Maybe eccentric motor failure? Lifters? Rocker arms?

Unfortunately, with what you are describing and with the limited information this may be one of those cases where you have to either take the valve cover off to diagnose it or take it to a shop to get it diagnosed and then you can fix it yourself. Hope this helps.

Rattle sound returned; checked Engine Oil level and was down to the minimum level....added almost 1QT to get back to normal level....seems this will be $$$..... will check rattle sound tomorrow (could not check Today).

So, after adding the Oil, Rattle is completely gone.....will keep checking stuff, I have a VC Oil Leak already identified.