Engine making noises...

[e34.535i.sport]

Just got out of the car after a long journey home in a hefty traffic jam. Don't know if this is relevant but thought i'd let you know just incase...

The engine is now making a randomly timed knocking noise as its idling... I can hear it best if i put my ear near the wheel arch on the drivers side (RHD) and the drivers door - its coming from down low. You can actually hear it easily when just stasnding by the drivers door, so its not quiet really. Could be from near the centre of the car but i can't be sure. The noise like a quick click now and again in this sort of way- ......^...^................^................^...^. .........^......^................^.^.

The dots are normal engine sound and the ^ is the noise. Its a quick click type knock and it seems to move the engine in the slightest-slightest way, as in you can feel it if you leave your hand on the valve cover. No real effect performance wise but the noise is worrying. When the noise happens the revs seem to drop ever so slightly too and rise again almost instantly (only measured by listening to it).

I can vaguely remember the noise happening now and again when i bought the car but much quieter and less violent (for want of a better word). I have changed the spark plugs and done a full oil/filter/air filter/fuel filter service.

Any ideas?

[Turbo Ready]

You mentioned knocking and clicking in your description, so have to be a bit more specific. If sounds like a metal knocking from within the engine, it can be quite a few things and a bit more serious.

If it's a clicking sound it can be mechanical or ignition related. Spark plug wire leakage will cause a clicking sound and will cause both engine shake and rpm drop.

Could be that the valves need a bit of adjustment as well.

Really hard sometimes to pinpoint some problems on a forum, best bet is to have a mechanic look at it.

[whiskychaser]

Best scenario is one cylinder just missing-could be just a plug. Worst scenario is a big end on the way out. Could even be a small end(con-rod end) You need to determine when it occurs. Hope its just a plug

[Alexlind123]

Many engines have a slight miss at idle. Its my understanding that unless the miss is present when accelerating, its nothing to worry about.

[bmwrp8]

might be the auxiliary e. fan... had that annoying tapping noise when my e.fan was on its way out

[e34.535i.sport]

Hey, sorry i often find noises really hard to describe the ones i normally encounter seem quite unique... I bet if some people heard it they'd know straight away! I would say that it is more of a click noise though i think...

Just went out again and started the car to try and get more details... Left it running for some time and give a few revs and its no longer making the noise.

Whiskey - I sure hope it is something simple but the sparks are only 4k miles old (ish) - could they still have problems? I did put some copper grease on the threads i was told this is the thing to do?... I wouldn't think the big end should be on its way out, the car has a comprehensive BMW/BMW specialist service history up to 120k miles and then self serviced from then i am told. It has been well looked after, and its certainly had EVERYTHING it needs immediately since i've owned it! :D

Turbo - it seems more like a click i'd say, and i think i need to change the valve cover gasket so i'm thinking of doing the valve adjustment... However, i am a bit dubious about it as it would be my first time.

Alexlind - That makes me feel a little better... To be honest though i have never really understood what a misfire would feel like. I assume i'd know though if i had one! The acceleration on the car is perfect - smooth throughout the rev range and very powerful. No go-stop-go business.

Bmwrp8 - By the aux fan do you mean the radiator fan (Viscous fan coupling?). I think it makes a noise when i shut the engine off but it could be something else its really hard to tell. However this noise has been present and doesn't seem to cause any problems?

I'm hoping its good if it's not a constant thing, as it doesn't seem to be doing it now. If it could be the valves, i'd serioulsy consider the adjustement, as i have the cover gasket in the boot already.

[Barney Paull-Edwards]

Any change in fuel consumption? An old 928 of mine had similar and it turned out to be two injectors, got them ultra-sonic`d end of noise.

[e34.535i.sport]

Any change in fuel consumption? An old 928 of mine had similar and it turned out to be two injectors, got them ultra-sonic`d end of noise.

You might have hit the nail on the head there i have been using more fuel... Can you explain more? What is ultra-sonic'd? Am i looking at a big expense here, the financial side of life isn't so good at the moment? Is there a way i can tell for sure if an injector is the problem?

[Barney Paull-Edwards]

Strip out injectors, no biggie, auto-box builders sometimes have an ultra sonic bath, works by very high speed agitation cleaning off deposits, same way they break up kidney stones(!) should be fairly cheap.

[whiskychaser]

You might have hit the nail on the head there i have been using more fuel... Can you explain more? What is ultra-sonic'd? Am i looking at a big expense here, the financial side of life isn't so good at the moment? Is there a way i can tell for sure if an injector is the problem?
Its all about sound. If you and me and a few others are listening to it on tickover we might come up with something. Mine sounds like its got asthma when I turn the key but give it a mo and its fine. Be good if we could download an audio file or something:)

[DaveVoorhis]

An intermittent ticking from down low could be as minor as the start of an exhaust leak.

[whiskychaser]

An intermittent ticking from down low could be as minor as the start of an exhaust leak.
Listen to Dave. He may not be happy about his wheels but he usually knows what he's talking about. Dont listen to me cos I will have the engine out before you can say Roger the cabinboy (ref to capt. Pugwash)

[DaveVoorhis]

Listen to Dave. He may not be happy about his wheels ...
If someone would like to drop some proper BMW wheels in my driveway (stock basketweaves, etc., will do), they can take away these:

http://shark.armchair.mb.ca/~dave/525i/misc/e39wheels.jpg

I have four of them, they are (to my knowledge) factory E39, and are complete with almost new but cheap tyres.