[MattBconsult]

Hey

So I've had my 63 plate 335d xdrive from new - FSH plus interim oil changes

I do a lot of motorway so now at 185k

Recently it's started to use a little oil (minimal) but that is to be expected

My problem is when cold I have a new top end rattle around 1500-2000 rpm - it goes away when warm - it's not the normal diesel rattle and is noticeable

I'm also (when cold) getting the drivetrain light for the first few mins of driving which goes away after a mile or so

Dealer can't find the issue and fobbed me off but I'm thinking it's maybe a bad injector ? Oxygen sensor or similar *

[JonyTarvis]

Hello mate,

Ok so this is a stab in the dark regarding the rattle noise and I could be a million miles away - but - something similar happened to me in a N47 engine and it was a simple solution so bare with me

When diesel engines are cold the detonations sound rough anyway as the walls of the piston and cylinder are not up to temp so the fuel around the corners doesn't explode all at once causing the engine to rattle/knock = vibration. Also, you stated it is happening at 1,500rpm onwards - that is when your peak torque is kicking in, again = vibration. And you mentioned it doesn't sound like the normal diesel rattle so I'm thinking outside the box here...

Check your plastic engine cover as it may not be seated properly. Best thing is to just remove it completely then see if that solves it. Sounds daft I know, but I had all the symptoms of what you've just mentioned and that was the cause, the noise it was producing was unbelievable from essentially what is just a plastic tray - could never get it seated back on properly so just left it off forever after that. They're only for aesthetics after all. Hope this helps

[shiftdnb]

I think I'm experiencing a similar issue while cold. No light though. I took a video of it and brought it in under warranty to have them look at it. They didn't seem to find anything and put it down to the engine being cold.

Listen to it with headphones to hear the rattling sound the best

[MattBconsult]

Originally Posted by JonyTarvis

Hello mate,

Ok so this is a stab in the dark regarding the rattle noise and I could be a million miles away - but - something similar happened to me in a N47 engine and it was a simple solution so bare with me

When diesel engines are cold the detonations sound rough anyway as the walls of the piston and cylinder are not up to temp so the fuel around the corners doesn't explode all at once causing the engine to rattle/knock = vibration. Also, you stated it is happening at 1,500rpm onwards - that is when your peak torque is kicking in, again = vibration. And you mentioned it doesn't sound like the normal diesel rattle so I'm thinking outside the box here...

Check your plastic engine cover as it may not be seated properly. Best thing is to just remove it completely then see if that solves it. Sounds daft I know, but I had all the symptoms of what you've just mentioned and that was the cause, the noise it was producing was unbelievable from essentially what is just a plastic tray - could never get it seated back on properly so just left it off forever after that. They're only for aesthetics after all. Hope this helps

Thanks for that I will give it a go - as mine is throwing the drivetrain light I'm pretty sure it's something else but will rule it out