Contour Enthusiasts Group Archives Forums General Troubleshooting How to tell if alternator noise?

I get faint turbo-like sound at low rpm. How can I determine if this is alternator whine?

It's original battery and alternator since 1998. No problems starting or lights dimming so far. Is there simple check I can do?

Tony, Thanks for the info. I will do the tests and come back. The other article was good read too.

Ok, finally got a chance to do the quick checks.

Engine idle, battery voltage reads 14.4V

Engine off, lights on for 1 minute, voltage reads 12.03V

So it seems it's borderline case for battery replacement. Is that your assessment too? What would you do?

Too late I went ahead and changed the battery.

I haven't driven a distance yet so it's hard to tell but will report back after Monday.

I've been having power windows that struggles to close and with fresh battery it's zipping up faster. So maybe it will work out.

My battery replacement effort was worth it. The whining noise has been reduced to barely audible and there is snap to how the power windows operate.

I should also mention the old battery had a lot of corrosion around the terminals. I've maintained it best I could by brushing off the corrosion and spraying it with the terminal protector several times over last two years.

All in all $40 well spent. (If it means delaying replacing my alternator another 2 years it's worth it's weight in gold!)

Just a point of information. Cleaning off the tops of the battery terminals when they are corroded really does very little good. The connections need to be taken apart and cleaned thoroughly, to the point that the contacts become shinny bright. If this is not done, the poor contact caused by the corrosion creates high resistance which means a poor connection. Take them apart. Soak them in a baking soda and water solution. Wire brush them. Scrape them if needed. Then reassemble with some sort of corrosion resistant material. I use dielectric grease, and most any grease will do. After everything is assembled, spray paint over the top of it may help as well.

Thank you, Jim, for ever-prudent advice.

Just a little clarification though, when reassembling the connection, apply grease AFTER tightening not before. Metal to metal contact(crimp and battery terminal) is the critical junction and nothing should be in between.

Put the grease between the connections. The tiny film will not be a conductivity problem and it will help keep the corrosion from coming back between the connections.

The electrical effect of the film of grease is nil, but the effect of even a little discoloration from corrosion can be massive.