knocking noise on start up
 

hi, i have a 2002 x5 4.4i, lately iv been noticing that once i have driven my car around for a while and then parked it up for a couple hours and then go to start it again i get this knocking type noise on start up which lasts for a couple of seconds and then vanishes, it never seems to happens on first start up in the mornings, its always after its been driven and then parked up for a while.

any ideas what could be causing this?

Any help would be much appreciated

thanks in advance

My 02 4.4i had this noise that turned out to be WP bearing start to go. I thought it was cam sensor but no.
Are you on your original WP? mine was doing it, started around 55kmiles.

Hi mate, I'm assuming you mean waterpump, if so it has had a brand new one fitted, did your make the knocking noise on start up then vanish after say 2 seconds? And did it happen everytime, thanks for the response

Maybe more, for about 5-10sec, but not all the time.
Did you replace both belts?

No I didn't end up changing the belt, do you think it could make difference? The mechanic did say that the belt didn't look to good, its been booked in to have it changed though!

Not 100% sure if it's the belts but might as well change them if you haven't done it.
Also check the tensioners as well while you are at it.

If it is accompanied by a bit of a rattling type sound it could be timing chain related. Cam sensors start to fail and on start up the timing is messed up so you get the loud intermittent knocking and rattle. They are easy to change as a DIY item and are routine item to replaced at 100K or so.


Mike

cool thanks for your help

[QUOTE=Mikedd;725512]If it is accompanied by a bit of a rattling type sound it could be timing chain related. Cam sensors start to fail and on start up the timing is messed up so you get the loud intermittent knocking and rattle. They are easy to change as a DIY item and are routine item to replaced at 100K or so.

hmmm interesting , i will have to check for a rattle noise the next time it happens, its in the bodyshop at the moment as someone has run a key down the whole side. if it was a sensor causing it then would it not happen everytime i started it? it really only happens after its been driven and then turned off for a couple hours and then restarted, never happens on the first start of the day. thanks for the response

VANOS.

Replace the intake cam sprockets, solenoids, and the one way oil valves that attach to the front of the heads.