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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Sun, Jan-13-2013, 01:47:25 PM   #11
Obioban
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Default Re: Developed an engine knock on cold start :(

Knock on cold start is normally a sign of very far gone rod bearings.

I would stop driving the car and get oil analysis at the minimum, or just drop the oil pan and do them.

How many miles on your car?
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Old Sun, Jan-13-2013, 01:56:16 PM   #12
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Default Re: Developed an engine knock on cold start :(

Wow, thanks for the feedback.
The car has about 40,000 miles. I didn't expected rod bearings issues so early.
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Old Sun, Jan-13-2013, 05:43:20 PM   #13
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Default Re: Developed an engine knock on cold start :(

Might not be. Do oil analysis and see what comes back. Cheap check.
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Old Sun, Jan-13-2013, 10:40:56 PM   #14
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Default Re: Developed an engine knock on cold start :(

hmm what is this knock sound ? any video clips?
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Old Mon, Jan-14-2013, 10:45:13 AM   #15
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Default Re: Developed an engine knock on cold start :(

I will take a movie clip (incl. sound, of course) next time when I start the car, and post it here. But that's not going to be earlier than next weekend, because the car is stored in a garage in another town.
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Old Mon, Jan-14-2013, 02:05:33 PM   #16
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Default Re: Developed an engine knock on cold start :(

You may want to get an automotive stethosocope like this:
http://www.harborfreight.com/mechani...ope-41966.html

People describe noises differently. Most rod knock's I've heard one can hear at idle.
Rod bearing noises are lower frequency, muffled (at first) thunk, thunk sound.
Valvetrains are more tick, tick. Higher frequency, more distinct. Also there at idle, harder to hear as engine speed increases.
I'd also check for vanos codes.

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Old Mon, Jan-14-2013, 05:40:03 PM   #17
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Default Re: Developed an engine knock on cold start :(

Quote:
Originally Posted by RobertRO View Post
I will take a movie clip (incl. sound, of course) next time when I start the car, and post it here. But that's not going to be earlier than next weekend, because the car is stored in a garage in another town.
Mine has almost 65k and i bought it in october with almost 60k.

I haven't thought to look into it because i haven't had the car very long but it certainy didn't "knock" on a cold start until it started getting pretty cold out (below 35 degrees in Chicago). My symptoms sound almost exactly like the ones descibed around this thread though which (of course) has me worried that my baby might be sick.

I'll post a video/audio of it when I get home later tonight and RobertRO, maybe you can identify if its the same sound?

See you guys in a few hours...
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Old Mon, Jan-14-2013, 06:41:37 PM   #18
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Default Re: Developed an engine knock on cold start :(

Quote:
Originally Posted by M3an0ne View Post
I'll post a video/audio of it when I get home later tonight and RobertRO, maybe you can identify if its the same sound?
See you guys in a few hours...
Great idea. Considering the time zone difference, it may take a few extra hours for me to reply.
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Old Thu, Jan-17-2013, 10:37:44 PM   #19
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Default Re: Developed an engine knock on cold start :(

haven't forgotten about you... my car hasn't been doing it the past couple of days. not sure why. i'll give it another try tonight. seems it keeps getting camera shy.
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Old Sat, Jan-19-2013, 05:40:42 PM   #20
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Default Re: Developed an engine knock on cold start :(

Today I reached the garage and took a closer look at the knock I have reported about a week ago (ref: my first post in this thread).

I have also recorded a sound file for about 7 minutes, from engine start.
Unfortunately, the only recording device was my Android phone. I hanged it about 30cm / 1 foot above the engine. Listening to the record I can tell for sure that it sounds very different than the real thing. It's obvious that the phone microphone has an odd sensitivity for sounds outside the human voice frequency interval. The knock sounds more like scraping /grinding in the record, than knocking. You can identify it by it's rare repeating rate: about 4-5 times/second.

The engine was started from dead cold (temperature in the garage: 5 deg. C / 41 deg. F, previous start: 7 days ago).

Here's the sound file:
http://82.78.8.129/mye28/z4/Tel-rec_S54_19ian_1.3gpp
(file size: 3.46MB, file format: .3gpp)
- moment of engine start in the above sound file: 00:24;
- the knock I am complaining about can be heard during the following time intervals in the sound file:
04:17 - 04:29
04:39 - 04:40
04:46 - 04:47
04:55 - 05:14
05:17 - 05:28

I noticed the following:
- I haven't heard the typical rod bearing knock, which usually happens during the first few seconds after starting a cold engine. And today my engine was really started from dead cold (temperature in the garage: 5 deg. C / 41 deg. F, previous start: 7 days ago);
- the knocking I am complaining does not show up for almost 4 minutes after engine start;
- then it happens, around 1.400-1.500 rpm only, either when the throttle is held constant around this rpm range, or during transition up/down through ~1.500 rpm;
- after the engine heats up, the knock goes away.

Unfortunately I was alone. If I had an assistant, then he/she could have actuated the gas pedal, I can could have listen closer to the engine.
By the way: is it possible for a person to operate the throttle while sitting in front of the engine with the hood open? In the good old days of cable throttle, that was very easy. But now?

Based on the above, I am more inclined to suspect the VANOS than the rod bearings. But it's nothing more than a suspicion.

I will highly appreciate any feedback.
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Discussing Developed an engine knock on cold start :( in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)