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Discussion Starter #1
Recently, I have noticed that there is a brief rattling or clacking noise coming from the engine on a cold start. The noise doesn't always occur on every start, but when it does happen, it's always on a cold start. Once the engine is running the noise either stops or is simply drowned out. I can't really tell. Any subsequent start within a few hours has no problems.

Given the symptoms, my only guess right now is that it is something that is not getting enough lubrication on the cold starts. Has anyone experienced this before? I'm not sure where to start looking for the root cause or if this might be pointing to something more serious.

Thanks.
 

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Recently, I have noticed that there is a brief rattling or clacking noise coming from the engine on a cold start. The noise doesn't always occur on every start, but when it does happen, it's always on a cold start. Once the engine is running the noise either stops or is simply drowned out. I can't really tell. Any subsequent start within a few hours has no problems.

Given the symptoms, my only guess right now is that it is something that is not getting enough lubrication on the cold starts. Has anyone experienced this before? I'm not sure where to start looking for the root cause or if this might be pointing to something more serious.

Thanks.
Check oil level, how many miles on the motor? Could be vanos or a timing chain tensioner.
 

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Open the bonnet next time you do a cold start.
Listen to where it's coming from.
If it's VANOS and it disappears after a couple of seconds, it's not an issue.
It's due to oil leaking out of the VANOS units, due to the O-Rings getting hard with age.

Dr VANOS has a replacement seal / O-Ring kit for this.
 

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Even after a full Vanos rebuild some cars still have the rattling on cold start up.This is usually pre-MY 2001 without the shut off valve for the Vanos pressure accumulator.
This is why there is a service information from BMW around with the retrofit of the newer style,if customer complained...

Cars built from 09/2000 to 11/2000 usually have the connector for the shut off valve accumulator in the wiring loom..After 11/2000,all cars have it fitted...

Cars before 09/2000 need the wiring for the shut of valve and update of the software.


Also bear in mind,that the pressure accumulators are filled with NOx and loose after 10 years quite a bit pressure....
 

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Could also be the starter motor. I had a similar noise:

YouTube - VANOS noise?

It lasts for maybe 1-2 seconds immediately after startup. Replaced the starter motor and the sound went away. Luckily the teeth on the flywheel weren't damaged too badly and didn't need replacing.
 

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Discussion Starter #7
Check oil level, how many miles on the motor? Could be vanos or a timing chain tensioner.
Oil level appears to be OK at the moment, right between the two markers. Engine has 78k on it and I recently had the tensioner replaced when I had some other work done at the same time.
 

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Discussion Starter #8
Could also be the starter motor. I had a similar noise:

YouTube - VANOS noise?

It lasts for maybe 1-2 seconds immediately after startup. Replaced the starter motor and the sound went away. Luckily the teeth on the flywheel weren't damaged too badly and didn't need replacing.
According to the service history that I have, the starter was replaced at some point. The noise isn't quite as loud and doesn't sound like gears grinding. It's more like a metallic clacking, but it only lasts for a second or two on start up then disappears.
 

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Discussion Starter #9
Thanks for the tips. At least I have something to try to look for and listen to. I don't know whether or not it's a good or bad thing that the noise is intermittent. I'll post if I track down the source of the issue.
 
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