Hey All.....

Newbie here, and really like the advice and banter on this Forum!

My 2004 525i was bought August 2008 out of warranty and non-certified, but had it checked by non-dealer mechanics and was in good mechanical/electrical condition.

I am made aware here of some of the problems of engine-compartment noises in the various models. From the outset, my car had a low-pitched but constant chatter or grinding sound at idle only which would immediately disappear as the RPM's went up with slow or fast acceleration. It also became muffled if the car was shifted from drive to neutral at rest. As many have pointed out, these sounds are annoying in the least for an expensive car!

I was concerned this was valve-lifters or other engine generated problems, but it was not an intermittent or tapping-type noise, and the car runs quietly at speed.

After two repair shop visits, the conscensus is AC Compressor noise from the newer type compressors which run continously without a clutch, and have a vane that directs the coolent flow for various temperature settings. The first 45,000 miles on the car was from a Florida owner, so I assume a lot of AC use!

In addition, the tension pulleys and water pump on my car were replaced, and the sound is less noticable, but persists. Apparently the cost of a new AC Compressor repair is around $1200. As the mechanic said, you can get used to some minor annoying sounds for a long while for $1200!

 

The AC noice is a bit high in the non-LCI models, it's somewhat lower in the LCI.

 

the dealer replaced the AC compressor 2 times. It's less noisy now but I can still hear it. here's an option. Instead of spending $1200 for annoying AC compressor noise, spend $1200 on an ECU remap and a tune. Then the sound would negate the whine.

 

Dose it almost sound like a random rattling coming from right under the valve cover in the front of the motor to your left while standing in front of the car?

 

There is the usual "valve clatter" noise that is regular in frequency coming from the engine, particularly before its warmed up and idling in cold weather. I attributed this to being normal for the 184 HP in-line six. Maybe I'm wrong here, but I'm not sure I want the engine toyed with out of warranty. The engine compression and computer was checked and is A.O.K. I believe the sound I'm hearing that's disappearing with increasing RPM's is more like a fan belt or small rotor-type noise, but I could be ($$$$) wrong!