Engine whine e70 4.8

[skeeattle]

I recently replaced my alternator with a NEW OEM Valeo alternator and tensioner pulley and ever since I replaced these I am getting a whine. I only hear it over 2 rpms and it doesn't have to be in gear and I cant figure out where its coming from or if its vacuum or mechanical in nature. I hear it more in the drivers area. I thought it was the alternator so I returned it and replaced it again and then I thought it may be the tensioner so I replaced it with a new OEM tensioner. My last guess is the belt but its just ironic that it would all of the sudden be the belt. Its not a power steering whine in nature and again, ironic that it is all of the sudden it would be the power steering or water pump. I couldn't find any vacuum leaks and I recently replaced both CCV's. Any help would be appreciated. I'm at a loss

[jfoj]

Is the whine actually from under the hood?

The reason I as this question is often if there is a bad ground you can get AC ripple from the alternator that then is amplified by the audio system and can be heard in the cabin as a faint background whine that will increase with RPM.

Usually this is due to a bad connection or ground wire loose.

The problem/trick is if you are not aware that there can be whine from the audio system, if you remove the alternator belt, the whine will go away and you might think the problem is the alternator.

Assume you have removed belt(s) in an attempt to isolate the problem?

You might see if there is a amplifier fuse that you can pull to isolate the audio system.

[Doug Huffman]

Originally Posted by jfoj

[ ... ] You might see if there is a amplifier fuse that you can pull to isolate the audio system.

Or just turn it OFF.

[jfoj]

The reason I suggest to pull the audio amp fuse is because on many of the newer audio systems, the main power amp is not fully turned off when the radio head unit is turned off. Also sometimes the audio amps do not shut down as designed.

Just suggesting a good way to fully isolate and remove the audio system as a possible problem if the noise is not specifically determined to be from under the hood.

I have a VW with the Monsoon audio system with an external Amp in the trunk. After some repair at the dealer many years ago, there was a whine in the audio system. I know it was an alternator whine the moment I heard it.

If it was worse with the head unit on, but turned all the way down, if I turned the head unit off, it was better, but the main amp did not fully shut down when the vehicle was running. Turned out that the battery cable from the alternator where it connected the battery was finger tight. A 10 mm nut driver and a few seconds later the whine was resolved.

[skeeattle]

Correct, jfoj. You have to pull the fuse, the amp is always on...at least if you have a CCC unit. I pulled the fuse to the amp and the noise is still there, I even covered the speakers with towels to double check, but thanks for the suggestion. I haven't pulled the belt off yet and ran it, I will try that this weekend. The whine is more noticeable toward the middle rear of the engine making more pronounced in the cabin area but you cant really hear it if you open the hood. I may have to do the long screwdriver test. One more thing to maybe offer some clues: When I first start the car I don't hear any whine then about 10 seconds later the whine starts. I want to think vacuum related but there E70 has very few vacuum areas that can go wrong besides the CCV, which I replaced both about 1000 miles ago. P.S. The alternator tensioner makes no sounds either. Since I will be taking the belt off anyways (3rd time down there) I will be replacing it with a new one, just to see what happens.

[jfoj]

Do not forget to rule out things like DME box fan if the E70 has one, the climate control fan, the HVAC blower (usually sounds like crickets in early models).

But removing the belt(s) can rule in or out accessories and pulleys.

Do not know what is in the cowl area, but when cold on my E70 I hear a slight rhythmic moaning that may be HVAC blend doors or something. Not concerning, but as someone that is "aware" of things, I have noticed this.

I assume it is "normal" but I have not had a chance to drive another E70 for any period of time when the weather is cold.

Let us know what you find.