So I think (rather know) I have a problem that I can't figure out...can you help me?

[BMW4LIFE]

First problem

I noticed that under acceleration I hear what sounds to be like marbles in my engine or engine compartment...what could it be? Knock sensor?


Second problem

I noticed that when the car changes gears...it makes what sounds to be like a click or clunk noise. The shifting is VERY smooth but the noise still has me worried. Could it be the tranny mounts? The engine mounts?

Thanks guys!

[e34.535i.sport]

I noticed that under acceleration I hear what sounds to be like marbles in my engine or engine compartment...what could it be? Knock sensor?

Never had it but from what I've read it sounds like pinging or pre-ignition? It's to do with the fuel igniting at the wrong time due to incorrect temps etc - Have you recently changed the sparks? I've been advised on the XJR6 forum that they have temperature ranges and if you use 'hotter' plugs you might suffer from what you describe... Also try using some higher octane fuel that might help... Someone else will hopefully be able to elaborate.

[bsell]

Vote number 2 for looking at the plugs. Check for proper model/heat range and gap.

Look at them to see if they are sooted up. I'm leaning towards excess carbon build-up in the combustion chambers causing your knocking noises.

You didn't say but she is running smooth as glass, right? No heavy thumping misses...if so, you could have broken something like dropped a valve or some such.

[632 Regal]

pre-ignition. Like mentioned what have you changed and look at the plugs. Use higher octane fuel as they are sending out complete crap as of late in amerika. Your spark sensors could have come unhooked (corrosion etc) causing the marbles.

Marbles under hood/Nut behind the wheel, we need more of these exclusive E34 terms.

[BMW4LIFE]

@e34

I was running bosch plat +4 then changed to the OE Bosch that BMW installed when the car was new. I do have to remind everyone that the noise is VERY subtle but if I roll all the windows up and turn off the radio I can hear the noise if I really try.

as far as the fuel goes...I use 91 octane (highest possible)...I want to try 87 and see if there is a difference in the noise...good idea?

@bsell

"excess carbon build-up in the combustion chambers causing your knocking noises"

this could be possible...

and yes the car is running like a champ...to be honest I feel as though it runs better with the new plugs that before (~2K on the new plugs)

@Regal

Spark sensors? I know of none...can you please elaborate the location either on realoem or pics?

thanks everyone! =)

[BennyM]

I think I had this issue on my old 5er. Could be a bad pulley, or something having to do with the belt system. I believe my issue was caused by a sheared-off bolt on the power steering pump. The noise appeared after I replaced the oil pan gasket, and I don't think I torqued the bolts down properly. The pump or something near it rattled, like marbles in a can, when accelerating from a stop.

[e34.535i.sport]

Hmmm using the lower octane fuel would potentially make it worse if it were pre-ignition. If you still have the old plugs I'd throw them back in and see what happens (providing it ran fine with them) or even get some new one's of the old type. Cheap way to check if the sparks are causing the issue.

[e34.535i.sport]

Marbles under hood/Nut behind the wheel, we need more of these exclusive E34 terms.

LOL! Hahaha