Knocking on start up 2001 5 series v8 4.4 77k
Over the last few weeks my 5 series ahs developed a knock on start up, it does not always happen but it seems to be getting more frequent. It last just a few seconds and length of time it lasts for varies too. Once started there is not evidence of a knock. If the car is restarted immediately there is no knock. The car has covered 78k and has a good service history.
I had wondered if it’s a hydraulic valve that’s losing pressure over a few hours, once the engine has been started the valve is brought up to pressure.
Any ideas what may be ?
If it is a hydraulic valve how easy is it to locate which one, and replace it ?