patelE60

Sup all,

First of all, I would really appreciate all the input/opinion that anyone has to offer.

Problem:
Cold start in morning..after warming up few mins when start driving..there is humming/scrubbing noise that comes from backside of vehicle...like vacumn sucking air in and out...
rpm jumps 200/300 up and down as car drags..
eventually goes away after 3-4 miles/ 5 mins driving..

starting at evening...going home from work...soon as start driving..there is ticking noise from front...lasts about 5 mins and goes away.

went to Indy shop today diagnosed it...came back as
misfire 1...alternator not charging...ibs cable also needs replace.

had battery replace about an year ago...

Indy is quoting:
415 for alternator + labor [few hundred]
220 for Ibs cable + labor..

does anyone else have this problem/solution?
can i go to pepboys/advance auto part for alternator ...would it be cheaper?

please help!!

pcy

IBS tells how much charge needs to be sent to the battery from the alternator. Failed IBS won't make those noises you described. The ticking noise from front may be from the alternator pulley.

Assuming the diagnosis is accurate...
Alternator can be rebuilt (typically, the bearings and brushes are replaced) for less than $200. Is that price of $415 for brand new or remanufactured alternator?
What engine are we talking about? If it's N52, it' really easy to replace alternator.

BimmerFan52

I looked over your post but can't find the model and year of your car, so I can only relate cost to my 2004 545i.

First, why is your mechanic saying the alternator is bad? You don't mention that the battery ran down and didn't eventually wouldn't start the engine, or that you are experiencing other electrical errors. You need to determine why he is suggesting the alternator needs to be replaced. Did he put a voltmeter on the alternator to test output? I am really scratching my head as to why a bad alternator would cause noise at the back of the car. If rubbing at front of car is the pulley or belt maybe only the pulley or belt needs to be changed. Alternator price mechanic quoted may be high for a new alternator, depending upon which model you have and way high for a rebuilt unit. IBS price sounds about right.

When an alternator goes it will either not charge the battery anymore, or it will be erratic in its voltage output. In my case one day the dash lit up like a Christmas tree with errors at start up. I inserted a cigarette lighter voltmeter I have and discovered the voltage regulator on the alternator was going bad. At start up the voltage output of the alternator would jump to 17V and then drop to 11.5V. 17V can quickly fry computers in the car so I had to replace it immediately.

I replaced my alternator with a brand new OE Valeo unit. Cost (brand new) was $283 delivered. Because the fan shroud and fan must be removed during replacement and I was still running the original water pump and thermostat at 85K miles I decided to do the water pump, thermostat and belts as preventive maintenance along with the required alternator replacement. The engine bay on the 8 cylinders is ten pounds of s**t in an eight pound bag so it is very tight, but definitely a doable DIY job. Previous poster is right in that the 6 cylinders are much easier to work on.

Alternators can be successfully rebuilt, but you must know who is doing it and trust them, as there are some really sloppy rebuilders who take short cuts. You can end up with an alternator that lasts a very short time. Yes they generally come with a warranty, but then you end up paying labor twice or doing the job yourself twice if it goes bad. Also, if you are going to get your same unit rebuilt (normally you swap your core unit for the rebuilt unit) the car will be down while your unit is repaired.

I would dig a little further or get a second opinion before you spend $1000+.

patelE60

I have 04 530i [M54], sorry forgot to mention it.
the reason Indy is saying Alternator is cause that's what came up when he diagnosed it. that alternator is not getting enough power to charge.
His explanation is first change the alternator and maybe it will fix everything else...sometimes alternator cant distribute enough power and car gives faulty errors.
I dont mind going with what he says...but again what if that doesn't fix my problem..and he will tell me something else for another $1000.
i just spend $2000 on car week ago for tire..n complete brake..cant afford to keep on spending.
PCY and BimmerFan52...really appreciate your input..thank you guys.

patelE60

I have no other electrical issues at all...battery is fine..not getting any errors..changed it less than year ago. He didnt put voltmeter on.

BimmerFan52

He would have put the voltmeter across the positive jump terminal and ground terminal under the hood to test battery voltage before starting the engine and system voltage (alternator output) while the engine is running.

You can test the electrical system yourself. Pick up a unit similar to the one below. When you turn the key to on (but don't yet crank the starter) the voltmeter should read 12V. Then after starting the car the voltage should begin ramping up over 10-15 seconds to about 14.2V then after a short time settle back down to 13.8V to 14V.

If the voltage goes above 15V then your alternator voltage regulator is faulty. The fact that your battery is not running down suggests the battery is being charged by the alternator.



Alternately, take your car to any National auto chain. They will computer test your battery and alternator for free and tell you on the spot if your alternator is faulty.

Replacing the alternator is a relatively expensive first step if your mechanic is not sure.

patelE60

Will check the alternator voltage, thanks.

Still leaves me with problem of rpm raving up and down..in cold start. and scrubbing noise that i get from muffler [back of the car].

thanks for your help. really appreciate it.