noises

Wed Jul 09, 2008 12:52 am

My sport has recently started making a loud knocking and a light tapping sound, they both started at the same time. The loud knocking is on start up from cold but goes away when then engines is going for a minute. The light tapping is there all the time and increases with the revs. I have changed the oil and filter, checked the clearances on the tapets which helped slightly but not much. I have put this to a few people and they say the tapping could be either eccentric adjusters or a broken valve spring. Car had been running mint before and this just started with out of the blue. Any help is very welcome

Wed Jul 09, 2008 9:06 am

Three things make tapping/knocking noises from the top end of a 325 engine.
1) Valve gear related noises, from incorrect clearances or broken/worn components. Will always make some noise. If it's a noise that started suddenly, it's probably just one valve, so take the cover off and locate the noise with a stethoscope (or metre length of garden hose).
2) Injectors. Primitive design of injector, which is noisy, and not enclosed like on modern engines, so the noise is more noticeable. Rev the engine, and switch off the ignition at high revs. If the noise stops instantly, it's probably from the injectors.
3) Leaking exhaust manifold or cracked manifold. This one can be temperature sensitive, as the crack can close up as it gets hot. If you do the injector test, as above, this one also goes nearly quiet when you kill the ignition.

If the ticking is audible in the cabin, take the centre cap off the steering wheel and make sure the hole through the centre of the steering column is plugged.

Wed Jul 09, 2008 10:13 pm

The knocking noise only seems to be there on start up from cold which made me think something to do with oil, when th oil presure builds it goes away. The light ticking is there all the time but when i rev the car there seems to be two seperate noises, which i thought something to do with two of the valves. Thanks for the info, will check car tommorrow

Sun Jul 13, 2008 4:44 pm

Gonna monitor this one as my 318i does the same (the 'ticking' noise). As soon as I can get in the garage, i'll take a butchers. Feedback to follow..........

Sun Jul 13, 2008 5:46 pm

Mine does the tiking, been told its the injectors, or very unlikeyl the tappetts. The kncking ould be slight bit of piston slap?

Mon Jul 14, 2008 10:05 pm

Seems now that the sport thinks theres not enough oil in the engine as the oil level light has decided to come on and off from time to time, theres nearly 5litres in it so could be just a nackered sensor, but when i put a bit of oil in the to top it up the noises all went away for a minite then came back making me think a weak oil pump. Anybody have this problem? Going to replace the eccentrics to see if that helps, ill keep you posted.

Fri Aug 08, 2008 5:39 pm

Fitted new eccentrics today, set the clearances at 0.025 and made no difference. Had a feeling at the start it was oil starvation and after a chat to Rich at Fritz Bits he said the same. The drive hexagonal drive shaft must have worn and hasnt the grip to spin the oil pump up to full presure. Hope so anyway, one on order so fingers crossed

Sun Aug 10, 2008 12:06 pm

been looking out for comments on this, as my 320i has the same ticking. I can hear the ticking at idle from the top of the engine (sounds like a loose tappet?) , goes away between 1000 & 3000rpm in 2nd & 3rd gear (funnily cannot hear it in 4th or 5th), then I can hear it slightly as the revs increase until 4000rpm and then it disappears!.

I use BMW 10/40 oil, if that makes any difference?? as an oil change is now due I am thinking of using 15/50, probably better bearing in mind the hot climate here.