Alternator whine - but its not the usual suspects....

[Jimxms]

Ok guys I did some more testing today, and I'm still stumped.

* I sprayed water on the alternator pulley and belt. It didnt make any difference to the noise, making me less suspicious of the belt.

* Then I connected jumper leads (both + and -) direct from the alternator to the battery. No difference. Note: I forgot to disconnect the alternator wire though...so this may be a false test.



* Then i plugged in my OBD2 scanner, and checked the BCM for charging data. It appears to be pulling about 60A:



I wanted to double check this with an amp clamp, but unfortunately I only have an AC one, so it didnt work.

* Then I checked for tensioner markings. I couldn't find anything definitive, so here are some pictures:



* Finally I Ohmed all of the cables and routes that power would take:

Positive Wires
+ Wire that goes from alternator to fusible link = 1.8ohm
+ One side of fusible link fuse to other side of fuse = 3.1ohm
+ Positive battery post to battery side of fusible link = 3.4ohm
+ Alternator post to positive battery post = 10.2ohm

Negative Wires
- Alternator body to chassis post on firewall = 7ohm
- Engine block to random bolt on body = 5ohm
- Battery terminal to engine block = 4ohm

 

[j91z28d1]

sadly the ohm reading doesn't tell you much, even thou some of those do seem a bit high, but could just be the bolt heads and probe not making perfect contact. the meter just runs a small amount of voltage thru the wire, it doesn't give you much idea of what's happening with 60amp running thru it.

this is a simple way to give you good info with just a standard volt meter.

shame about the meter but if the obd reading is correct, 60amps shouldn't really made it whine.

I'm kinda out of ideas. maybe some others can help.

 

[Jimxms]

Bit of an update....I did the "big 3" upgrade using 0/1AWG wire and i think the noise has decreased. It seems to only whine (but at a lower level) for a few minutes at startup and then by the time I'm on the freeway its no longer noticeable.

I guess my question now is: Is everyone elses alternators completely silent? Or is a small amount of whine normal? Other cars I've owned have had zero alternator noise (Corvette, Firebird...etc) but all of them probably have lower power consumption needs.