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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 02-28-2012, 06:39 PM
PerfectStorm01 PerfectStorm01 is offline
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Got good ears? AC compressor or Fan Noise

After replacing my belts and pulleys last week, I'm now starting to hear other noises. I know my AC compressor may be on its way out cause it makes a bit of a squealing noise at lights when it's on, but this noise is a bit different than that.
This is right after I started her up in the morning. Around the point of 7-19 seconds on the video I hope you can hear a sort of loose rotating noise almost a low rattling hum. At first I thought it was my ac compressor pulley since I've replaced belts and tensioners and maybe the added tension is making it sound this way. My other guess was my fan. Is it possible the fan is off balance? It seems pretty steady in the video, but while I was performing the DIY I stored it flat in my trunk.

My car has 92K miles. Oil level is perfect. I've recently replaced the thermostat, waterpump and the rest of the cooling system.

That loose plate at around 40 seconds is driving me crazy cause that rattles too. The other plate is tight and doesn't make a noise.

Here is the link:
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  #2  
Old 02-28-2012, 06:52 PM
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In the video your engine sounds fine. The noise from the fan is also distorting the other sounds. The A/C compressor never kicked in so I didn't hear anything wrong with that. You can pull that heat shield off with a pair of pliers and working it up and down a few times while pulling, it'll pop right off. But I'd live with it, it doesn't sound bad.
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  #3  
Old 02-28-2012, 09:20 PM
PerfectStorm01 PerfectStorm01 is offline
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Thanks Smolck. I really have to say that in the morning (especially after it was raining) my car sounds like it was up all night drinking and smoking like 10 packs of cigs. Sounds like a girl I dated at university. I drove it around for a good while on the hwy and back roads came home popped the hood and she was purring (with AC on).

I think I have to switch back to Mobil 1 oil. Currently it has whatever BMW put in it 2 months ago and it seems to rattle a lot more with it in there. I need to reread that thread you started regarding oil again.
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Old 02-28-2012, 09:27 PM
ckleung100 ckleung100 is offline
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Originally Posted by smolck View Post
In the video your engine sounds fine. The noise from the fan is also distorting the other sounds. The A/C compressor never kicked in so I didn't hear anything wrong with that. You can pull that heat shield off with a pair of pliers and working it up and down a few times while pulling, it'll pop right off. But I'd live with it, it doesn't sound bad.

I had a rattle too that I thought was that heat shield but it was the AC compressor. The noice was intermittent at first but got progressively worse.


Turn on the AC and set the temp to the lowest setting to force the AC clutch to engage and see if it makes the noise. As Smolck mentioned, the clutch never engaged in your video.

Last edited by ckleung100; 02-28-2012 at 09:29 PM.
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Old 02-28-2012, 09:46 PM
PerfectStorm01 PerfectStorm01 is offline
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Quote:
Originally Posted by ckleung100 View Post
I had a rattle too that I thought was that heat shield but it was the AC compressor. The noice was intermittent at first but got progressively worse.


Turn on the AC and set the temp to the lowest setting to force the AC clutch to engage and see if it makes the noise. As Smolck mentioned, the clutch never engaged in your video.
The AC was not engaged in the video because I could hear the noise without it on. But after a nice drive the car sounds good even with the AC on. I'm chalking it up to the first start of the day...for now.

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Originally Posted by ckleung100 View Post
I had a rattle too that I thought was that heat shield but it was the AC compressor. The noice was intermittent at first but got progressively worse.
Wow, really? Was there any other signs? Did the AC still blow cold? Could you wiggle the heat sheild? Did you change the AC side tensioner/belt? I'm very curious...
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Old 02-28-2012, 10:42 PM
ckleung100 ckleung100 is offline
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When I first heard the rattle it was driving me nuts because I didn't know where it was coming from. The Indy I occasionally take my car to told me it was the heat shield too and I could rip it off myself with a pair of pliers. I wasn't convinced it was the heat shield because I thought the noise should be more constant and not intermittent if it was so I never ripped it out.

I took me about a month before I realized the rattle only occurred when the AC was on, and then only when the clutch was engaged. The noise was coming from the compressor. Since AC repairs are usually pretty expensive, I ignored it since the AC still blew cold air but after another summer the noise kept getting louder. I took it to the indy to fix last summer when it no longer cooled.

I know even AC repairs can be DIY but the specialized equipment to too expensive. The machine they used pumped out the old refrigerant, filtered and stored it, and then reused it back into the system after the repair. You really shouldn't vent the refrigerant into the air like we did in the old days. It's worked out just as well that he did it because the system had a leak that was a bear to find. He must of pumped the system out 5 times to finally find the problem but he still only charged me the same amount he said at the beginning. I saved a bit of money by buying the compressor over the net and he agreed to install it for me. The caveat is he won't warranty the repair since he didn't supply the part. I could live with that since I saved several hundred on the part.

One warning that my INDY told me about. Let me know it anybody disagrees but he seemed knowledgeable. The rattle was basically the compressor disintegrating slowly inside. As it breaks down, there can be little pieces of metal that enter the refrigerant stream that adds to the problem. When they replaced the compressor and evacuated the system, they can't guarantee that the system is free of the metal shavings since the system is only evacuated, not flushed. That will take care of moisture in the system but not contaminants, especially it they have been pumped through the system.

I can only cross my fingers that the system is OK but the moral of the story is if your compressor is making a "death rattle", don't wait too long to replace it.

Last edited by ckleung100; 02-28-2012 at 10:46 PM.
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  #7  
Old 02-28-2012, 11:00 PM
PerfectStorm01 PerfectStorm01 is offline
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That is some good info-thanks. So far I have only heard the rattle in the morning after a cold start. I'm going to keep an eye on it and track when it happens and the conditions.

I am going to try to hold the shield to see if the rattle goes away because mine is super loose. My problem is in the morning my lifters make a similar noise until the oil is nice and warm.

$2600 big ones to replace the AC compressor at the dealership here.

BTW, love Toronto. Been there a couple times-damn cold!
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Old 02-29-2012, 06:21 AM
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Quote:
Originally Posted by PerfectStorm01 View Post
My problem is in the morning my lifters make a similar noise until the oil is nice and warm.
Pretty common I'd say. You could switch to Mobil 1 0w40 for a bit thicker viscosity and potentially calm the lifters down some. Some guys use a little marvel mystery oil with good results. Not sure it is available in your world, but here is what it looks like....



BTW, the comment about the girl in college was priceless! Too funny!
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Old 02-29-2012, 07:17 AM
ckleung100 ckleung100 is offline
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Quote:
Originally Posted by PerfectStorm01 View Post
That is some good info-thanks. So far I have only heard the rattle in the morning after a cold start. I'm going to keep an eye on it and track when it happens and the conditions.

I am going to try to hold the shield to see if the rattle goes away because mine is super loose. My problem is in the morning my lifters make a similar noise until the oil is nice and warm.

$2600 big ones to replace the AC compressor at the dealership here.

BTW, love Toronto. Been there a couple times-damn cold!
Not surprised the dealer wants $2600 to replace compressor. I never would have fixed mine if it were to cost that much. Worth more than my car.

My Indy charged me $350 for the compressor replacement + the cost to buy new compressor( I dont remember how much now. Used compressors are available but I didn't think it was worth the increased risk.


By the time it got really bad it sounded just like this....

Last edited by ckleung100; 02-29-2012 at 08:25 AM.
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