I have had this cold knocking noise since I purchased this CPO 545i. In colder months the knocking happens quite a bit louder and really is only heard when driving off between 1700 - 2100 rpm. Especially heard each moring driving out at 25 mph out of development.

A lot has been ruled out. BMW has changed the AC compressor and pulley, a vaccum solenoid, all injectors, new plugs, new ECM SW and VANOS checks out fine with new o'rings installed.

I have rode with the BMW escalation rep. He says that it is the difference in metals between the block and pistion. That until they heat up they are not expanded. Car does quieten up once driving for 15 to 20 minutes.

Engine is fairly smooth, gets 28mpg on the hwy and burns no oil between changes ( which have been around 12K miles according to history and my experience.) I have put 21k on the car since buying.

BMW doesn't want to do anything more and said that it really is normal noise. I am attaching a sound file that I took. My question is ( I know hard to say) but is it a possible rod noise?

The noise really only happens underload not when idleing. I have attached a file recording. Noise starts about 20 seconds into the clip. I am backing out of driving and then driving up the road to a stop sign then take off again. I never get about 20mph and not above 2500 rpm. Give me your feedback.

 

Can't say that's normal noise ... I don't hear that it on my 545i (*knock on wood*). I say escalate it or take it to another dealer, especially if it's CPO.

 

How many miles do you have on your 545i?

Do you feel the knocking noise?

What area from inside your car do you hear it from?

Does the noise stop when your car gets out of first gear?

 

I won't accept the answer that its normal or nothing is wrong. You motor isn't the first with this issue and some motors have been replaced because of it. Could it be a rod...... sure that would make logical sense. I'd push the issue with them. Ask yourself this and ask them this question, "If its normal, would you buy this car sounding like this?". Honest answer would be no one would buy a car making a sound like that. It needs to be fixed and that is all there is to it.

 

[quote name='GQuK545i' date='Aug 3 2008, 02:35 PM' post='638727']
How many miles do you have on your 545i? purchased with 41K now has 62K. It was a hot day when I purchased it and drove it. I brought it back 3 days later for this noise. almost a year later and 5 service visits and loads of BMW money the problem is still there. BMW regional rep said that new engine will not fix.

Do you feel the knocking noise? No do not feel

What area from inside your car do you hear it from? Sounds more to the front right engine area

Does the noise stop when your car gets out of first gear? No , noise is apparent in 1st, 2nd, 3rd as long as rpm is in that range 1700 -2100- Cold temp does affect the noise. When I say cold I mean 60. It is louder when starting off at 60 than starting for the firt time at 80 degrees. matter of fact if it is 80 degrees outside and first start of the day the engine may not do it at all. But when in the 70's and below I can count on it every first start or when the car rests for several hours.


SO yes I will be writing BMW NA. I have place to formal escalation requests. Next will be in writing. I can't imaging a 545i making a noise like this and it being accepted by anyone. This has taking a long time to get to this point, the 545i has been in once again 5 times and has spent anywhere from 3 to 9 days each time.

Just seeing if the noise and how it happens has been observed by any other 545i owner. or N62 for that matter.

Thanks

 

Is the noise more noticeable when you first start the car and becomes less noticeable as the car warms up?

The sound clip you posted suggests the noise is coming from the valve lifters/rockers.

 

Noticeable when engine is cold ( overnight sitting or long period of off time in cooler weather) and driving off. Noise is not present when starting or idleing at anytime. Can duplicate noise in park to some extent around 2K rpm but is more noticeable when in gear and driving off.

One of the first service appointments is where they pulled the vavle covers and measured the levers or looked for certain date stamps on them. All were ok.

I run what ever oil weight BMW NA puts in it I believe 5w -30. Could it be that I need a thicker 10w or 15w? Is the 5W too thin?

 

How come that BMW have changed parts if the noise is, according to them, normal?
Doesn?t make sense.

I first thought your concern was the ticking noise. Probably also what pukka thought?

But after reading your post closer I think I understand your question.

To me the hard "flappering" noise (26-27sec into the clip) when pushing the throttle on a cold engine is not that odd.
It is acctually normal that an engine sound different, hot vs. cold. Maybe yours is on the more noisy side of the scale?

My best guess on a noise like yours, that is escalating over time, is a sign of worn main cap bearings, con rod bearings. or wrist pin slap.
But if it hasn?t changed over time I would rule that out. Those parts usually fail pretty fast after the noise has occured.

 

sounds more like loose exhaust to me. Check the bolts on the headers and follow the exhaust back to make sure everything is torqued to spec.

That would explain why it goes away when the car is warm, as the metal heats it expands.

-felix

 

I can't get the sound file to work but what you describe, especially as it goes when the engine is warmed up sounds like 'piston slap'. Caused by the poor selection of piston outside diameter to bore inner diameter during manufacture. (selective build!)
Personally I would kick up a fuss until its put right....... NOT acceptable these days on ANY car let alone an expensive one.
Best of luck.
BTW you could always find an engine specialist and get them to take a look at the bores with a boroscope, they would be able to tell straight away.