x5 knocking on startup
 

Hi, I have a 2003 x5 4.4i and i've noticed that when I go to start the car after its been sitting for a while that there is a very loud knocking noice but then disapeares after a few seconds. What could it be?
Thanks!!

I have exactly the same noise from mine on start up, a few loudish knocks and only lasts about a second.

Will be interested to hear further replies.

:dunno:

Rod knock. What you are hearing is the beginnings of a rod bearing failure. The clearance between the bearing and crank shaft has opened to the point that when oil drains in to the crank case after sitting there is too much gap for that initial start up period. During that startup period there is a second or two where very little oil is present at the bearings as it has drained out. It takes the engine a second or two after starting to build oil pressure and distribute that oil through the engine. This is not heard on an engine in good shape as the bearing clearances are tight enough to prevent the knocking.

I'm not sure if the X5 will do this, but most drive by wire throttle cars can be cranked without starting if the gas pedal is held down to the floor. This is a good test to see if what you are experiencing is a bearing issue. On cold start on cars that are capable of this, one can crank the car for 5 seconds to build oil pressure then start as normal. If the knocking sound is not there after cranking for 5 seconds then it is definitely bearing related.

What kind of oil are you using?

ok, that is dissapointing because I just thought it was just vanos noise. How expensive is it to fix?
And I bought the car in May and have no idea what the previous owners used in terms of oil but I have always used the 5w-30 straight from the dealer. The x has about 99,000 miles on it

One man's clatter is another man's knock. Try and have someone with experience in this arena give a listen in person. Notoriously difficult to explain a noise.

Well said, I couldn't agree more!

I have the exact same issue... I hope it's not bearings...
A rebuild of the M62 would be epic!!!

From what I read here on the site it's just the Vanos, there's a thread about this so do a search. It gets noisy on high mileage vehicles, rod knock would not go away after a few seconds.

My '03 has been doing this since I bought it middle of 2006. Seems to be the case for most if not all of the M62s. I plan to do my vanos next summer.

I run Mobil 1 10W30. The engine runs very well and with new vanos it should be fine for another 100k.