35d tapping/knocking sound

[Andruha]

I have X5 35d with just 1,300 miles on odometer. During break in period I was quite gentle with acceleration. 2 days ago I decided to try accelerating a bit harder and noticed that between 2,500 and 3,000 RPM engine makes knocking sound that reminds me valve knocking on older cars. After 3,000 RPM it goes away. On park there is no knocking sound and engine runs smoothly at any rpm. Is it possible I got bad diesel at a gas station? Has anyone with a diesel experienced the same? Just a thought of something being wrong in a new, 1 month old car is driving me crazy TIA

[NPickles]

Originally Posted by Andruha

I have X5 35d with just 1,300 miles on odometer. During break in period I was quite gentle with acceleration. 2 days ago I decided to try accelerating a bit harder and noticed that between 2,500 and 3,000 RPM engine makes knocking sound that reminds me valve knocking on older cars. After 3,000 RPM it goes away. On park there is no knocking sound and engine runs smoothly at any rpm. Is it possible I got bad diesel at a gas station? Has anyone with a diesel experienced the same? Just a thought of something being wrong in a new, 1 month old car is driving me crazy TIA

If revving the engine in park doesn't cause the knocking noise to occur then it doesn't sound like an engine issue to me otherwise you'd expect it whether you are driving or stationary. It sounds more gearbox or drivetrain related.

Does it occur in Sport or Sport+ modes?

I've had my 40d for nearly 8 months now and have 13,000 miles on it with no noise issues.

[Andruha]

It happens at different speeds but always between 2500 and 3000 RPMs. Driving mode does not change it. Tried Comfort and Sport with no difference. Have not tried Sport+. I will try to see if I can pinpoint it to particular gear.

[NPickles]

Originally Posted by Andruha

It happens at different speeds but always between 2500 and 3000 RPMs. Driving mode does not change it. Tried Comfort and Sport with no difference. Have not tried Sport+. I will try to see if I can pinpoint it to particular gear.

I doubt Sport+ will make a difference if Sport mode doesn't.

Definitely sounds transmission related to me.

[NPickles]

Probably best to get that checked into you dealer so they can sort it before it turns into something more serious.

Let me know how long it is before they tell you that 'they are unable to reproduce the reported issue' this seems to be BMW's standard line for just about anything.

[Stano]

Is this your first diesel by any chance? What your explaining sounds like typical diesel noise when the car is under heavy load/flooring it.
At idle the car is very quiet, most people wouldn't even realize it's a diesel. Even with a moderate pedal while driving the chatter is never really noticed but when you floor it the diesel sound/chatter really comes to life and sounds like a diesel truck when it's hitting its peak torque
At idle even if you blimp the throttle you won't produce the same sound unless you really rev it up because the car isn't under any load

Doubt there's any problem with your car

[Andruha]

Thanks, Stano,
Yes, this is my first diesel. What bothers me is that it disappears after 3,000 RPM. Engine is still under heavy load past 3,000 RPM. I'll try to record the sound with my phone and post it in couple of days.

Thanks NPickles,
I am going to monitor it for next couple of days. Dealer is always an option, but to get results on your first visit is virtually impossible

[Wobbles]

Originally Posted by NPickles

Let me know how long it is before they tell you that 'they are unable to reproduce the reported issue' this seems to be BMW's standard line for just about anything.

Wow! Now that consistency for you! The BMW dealership over here says exactly the same thing too!

[Stano]

Originally Posted by Andruha

Thanks, Stano,
Yes, this is my first diesel. What bothers me is that it disappears after 3,000 RPM. Engine is still under heavy load past 3,000 RPM. I'll try to record the sound with my phone and post it in couple of days.

Thanks NPickles,
I am going to monitor it for next couple of days. Dealer is always an option, but to get results on your first visit is virtually impossible

It's all dependent on motor speed and even vehicle speed.
It's most apparent at the range you state it when flooring it below 2k RPMS because that'd where the motor is making the most torque. If you floor it from a higher RPM(say 2500+) theres not much clatter it more similar to a petro car then diesel.

Do this. Next time your in the car in park blip the throttle to 3k and blip the throttle again quickly while it's on the down swing(like 2500rpm) and you should briefly hear the same sound you've been hearing. If it's the same clatter your hearing your cars fine.

If you really want to hear the sound find a road with a decent incline/hill and smash the throttle from a slow roll or stop and you should hear the sound through out the rpm range

Stop worrying and enjoy the car.
I have a 2015 35d with 3500 miles. You will learn to enjoy the sound like I do

[Wardman]

I heard the same thing early on. sounded like a flat spot on a tire (out of round) but I think it is the engine sounding different and bouncing off the street into the cabin. I don't notice it after 4000 miles now.

[42pilot]

Originally Posted by Andruha

I have X5 35d with just 1,300 miles on odometer. During break in period I was quite gentle with acceleration. 2 days ago I decided to try accelerating a bit harder and noticed that between 2,500 and 3,000 RPM engine makes knocking sound that reminds me valve knocking on older cars. After 3,000 RPM it goes away. On park there is no knocking sound and engine runs smoothly at any rpm. Is it possible I got bad diesel at a gas station? Has anyone with a diesel experienced the same? Just a thought of something being wrong in a new, 1 month old car is driving me crazy TIA

In my opinion, there shouldn't be any difference in sound. Of course, heavy acceleration will sound louder, but you shouldn't hear knocking. What makes you think it sounds like valves? Is it light tapping or knocking?

Did you notice this after a fill up? The US has sketchy diesel fuel at discount stores and it could be poor fuel. It could also be water in the fuel, but BMW has pretty good sensors that will warn you of water in the system. Water will trash our injectors and will stop your engine, if there is enough water. The fuel timing (when fuel is injected during the compression stroke measured in degrees prior to top dead center - TDC) on diesel injection, if your fuel is bad, can make the engine sound like there is a tapping at certain RPM. Under heavy load, the tapping can get louder as the ECU adjusts/increases the timing to meet the new input requirements.

I don't think it could be tranny related as you checked the sport mode and there is no difference. Sport mode adjusts the engine's tune, but more importantly, it also adjusts the shift points and locks the torque converter earlier. This gives you improved throttle response and shifts the tranny in the sweet spot of the engine's power band (to prove this, press the sport button at 40mph and watch the tranny down-shift which increases the RPM to the be in the peak torque range).

Anyway, if you don't think it is fuel related, you need to have the dealer check this out as the engine should be consistently smooth and relatively quiet. Under load, it will be a bit louder, but consistently so through the RPM's.

[ioannisST]

This a known issue for ZF!!!!! Trust me and thank GOD pls for telling you change all solenoids of gearbox!!! Dont try for output or diagnostic scam!! Its secrect!! Enjoy my friend!! ZF has to stop this from cheaply made things