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05-09-2019, 11:15 AM | #1 |
e90noob
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HELP - what is this steady knocking noise?
UPDATE - the noise is almost certainly coming from the ac compressor
did i break my car? can anyone identify the noise? so I swapped out the TA's last Saturday everything was fine driving it back home over 70 miles from my friend's house but when I ran diagnostic at home I saw an error code for coolant temperature sensor drove it on Monday and Tuesday without any issue tonight, I heard a change in the noise in engine bay noticed that my fan wasn't running most of the time I drove it home since it's cool and moving air should be fine engine wasn't overheating the noise was not like this at first ... now there is a consistent knocking noise that sounds like ... it's plastic hitting something doesn't appear to be the fan the noise was there whether or not the fan was running the knocking increased in speed when i stepped on the throttle my totally noob wild guess ... could it be the little plastic arms that connect to the throttle actuator? when putting in the new TA, I did think it is crazy how little the plastic arms were gonna open up the car tonight night after work to check all the connections and see if i can identify the problem
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2008 E90 M3 / LCI trunk + euro tail swap
Production date - 2008-04-22 Last edited by XKxRome0ox; 05-10-2019 at 11:33 AM.. |
05-09-2019, 12:19 PM | #3 | |
e90noob
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I rushed to get my TA swapped because I have a track day on may 11 if I can't get this taken care of, I just threw away money on the track day registration fee and the expedited shipping on the parts I really really hope it is just something like I did not reconnect all the sensors and hoses properly
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2008 E90 M3 / LCI trunk + euro tail swap
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05-09-2019, 12:26 PM | #4 |
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Does the noise stay consistent with the revs when you rev it? Check to make sure you haven't shredded a belt and it's slapping something as it goes around.
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05-09-2019, 12:29 PM | #5 |
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the noise changes as the RPM goes up
i think it got faster as the RPM went up
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2008 E90 M3 / LCI trunk + euro tail swap
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05-09-2019, 12:35 PM | #6 |
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I'd check the belts, if you can get the car in the air and remove the bottom shroud you can pull the belt off the idler and start turning accessories by hand see which ones noisy, or if the belts shredded and slapping something as it goes around. I know you just did actuators the closest belt run accessory to that is the water pump I believe make sure nothings fouling against the pump pulley.
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05-09-2019, 12:47 PM | #7 | |
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I don't mind getting a little dirty and working on the car just wish I had a little more time buffer
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2008 E90 M3 / LCI trunk + euro tail swap
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05-09-2019, 02:30 PM | #12 | ||
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05-09-2019, 09:47 PM | #13 |
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remove belt and start engine. is noise still present?
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05-10-2019, 12:18 AM | #14 |
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took off plenum and rechecked every connection
it wasn't anything in there there is actually no fault code at all when I scanned today not even the coolant temp sensor which showed up earlier in the week narrowed down the source of the noise seems to be coming from the pulleys fan turns on when engine is at operating temperature no issue other than the noise how foolish is it to just take my car to the track on Saturday and deal with this afterwards?
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2008 E90 M3 / LCI trunk + euro tail swap
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05-10-2019, 12:50 AM | #15 |
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Very foolish..
This belt diagram might not be Correct but the accessories are labeled.. figure out which ones making the noise. Added a pic of the block and the thread I got the pics from https://www.m3post.com/forums/showthread.php?t=1162212
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05-10-2019, 08:29 AM | #16 |
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OP - instead of performing "Internet forum diagnostics," why don't you rush the car to your preferred Indy or local dealer?
Hopefully they'll patch you up in time for the track event. |
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05-10-2019, 11:12 AM | #17 |
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Do NOT track the car with bad belts. If you lose the water pump belt at a track, you will likely cook your engine. Been there with an M42 and boy it breaks things fast.
Get the problem solved first.
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05-10-2019, 11:22 AM | #18 |
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took it to a local indy BMW shop
belts and pulleys are fine almost certain that it is the ac compressor when I turn on the ac the noise goes away not a catastrophic item, right? so I'll go ahead with the track day and then address the ac compressor afterwards
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05-10-2019, 11:46 AM | #19 |
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Track is not worth the risk . Keep in mind , our S65 is not cheap my friend .
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05-10-2019, 03:23 PM | #20 |
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That's good to hear. You are probably low on refrigerant. I would say, give it a recharge and see if the noise disappears.
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05-12-2019, 03:39 PM | #22 |
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nope
the ac compressor totally crapped out the pulley cracked and fell off so the car is sitting at a shop now waiting for the compressor to be shipped this week thankfully it happened during tech check the night before and not while i was driving because losing power steering mid turn would have been real bad
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2008 E90 M3 / LCI trunk + euro tail swap
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