320d - knocking noise when cold start car

Bulmers

Hi All,

Wondering if anyone might have some idea as to what this is. With the recent cold weather, have noticed when starting car from cold, initially there is a loudish knocking noise for a few secs then goes away. I have tried leaving the key in to heat the injectors, it being a diesel but doesn't seem to make a difference.

Car has been recently serviced, no issues being reported by the OBC, anyone any thoughts what might be, it's a 06 model.

cheers

Owen

Could well be the crankshaft pulley. Mine went about 2 months back, knocking noise at startup, which over the course of 3 weeks became a constant knocking.

listermint

Oil isnt up to temp yet at these low tempretures so could cause addtional start up wear at the moment.

Did they change the breather filter at the service ?

Bulmers

RoverJames wrote: »

Did they change the breather filter at the service ?

no - was done on the one last year so they said didn't need to be done this year

Gumbo

PaintDoctor wrote: »

Could well be the crankshaft pulley. Mine went about 2 months back, knocking noise at startup, which over the course of 3 weeks became a constant knocking.

this a big job?
i have a slight permanent knock on my E46 too. when i rev it dissappears.

Bulmers

rang the garage so they couldn't think of anything it could be, oil and filters been changed last month and checked over and nothing showing up, didn't knock as loud this morning when started as not as cold as yesterday.

Still doesn't sound right, she's ok after literally a few seconds ticking over so must be down to the extreme cold. Didn't notice it in the last cold snap we had so maybe it's just something with age on the car, will see what happens

PaulKK

Probably just that the oil is cold and doesn't reach the tappets for a couple of seconds.

Has been like that on both diesels I have owned.

Owen

kceire wrote: »

this a big job?
i have a slight permanent knock on my E46 too. when i rev it dissappears.

It's not a big job, but it's a complete pain in the arse. I posted in the Motors Tech forum about it, with a photo of the crankshaft pulley afterwards - the rubber damping inside had literally crumbled away.

Prices for the pulley vary from BMW at about 320 Euro, to Irish Motor Factors at 190, to Europarts at about 90 delivered to the door.

phill106

I have similar in my diesel passat, goes when engine warms up. Not sure what it is, so if you find out, please share!

munzab

i had that for a while on an e46 01 318i. i think the guys told me it was normal and would cost to repair. it was an air pump or something along that line. it needed a little bit of tightening and the noise went away. its back now with the cold weather, but disappears after about 20 seconds.

Slick50

With the extra cold weather, all metal parts have shrunk slightly, the knocking is probably the tappets, or in some cars the shims. These actuate the valves, and have very high tolerances. It may be a sign that they need adjusting or replacing. This should not be an expensive job if needed. The cold will affect the oil too, ie reduce it's efficiency to a slight degree. But I don't think it is anything to panic about, unless it is really loud.

A permanent knocking is a different thing, it too can be caused by tappets or shims, but could also be a big or small end bearing on the way out. Now that gets expensive!