Alternator whine and battery flashing..

joshjwc9 · Apr 15, 2013

Well my 163k mile Vortech Mustang just has a little problem. Took a turn a little spirited today and noticed the battery light come on and flash a few times before going off. Now alternator has a whine that increases with engine speed. I ordered a 160 amp off of eBay. Is the car okay for the 10 mile trip home where it'll be parked til new alt comes in?

trinity_gt · Apr 15, 2013

If the sound is mechanical you might be pushing it. If a bearing has failed I wouldn't trust it. Take the belt off and check the shaft play -- axial and radial -- to judge whether the bearings are fit for service.

If the sound is electrical it's likely the alternator has blown one or more diodes and is probably okay to drive. You should use a voltmeter -- beg, borrow or steal -- and check the alternator output. If the regulator has gone off the reservation you can get very high voltages out of an alternator. Check the DC reading with the engine idling. If the alternator light is on I expect you to see 12V or less. Anything over 14 and I would disconnect the alternator completely making sure to completely protect the "big" wire against shorts. You can blow a lot of electronics if the alternator output is unregulated...

joshjwc9 · Apr 15, 2013

The blower makes this difficult to take off the belt. Charge light flashed several times then went off for the remaining 2ish miles to work. Sound remains though when car is idling. Where do I measure alt output?

trinity_gt · Apr 15, 2013

joshjwc9 said:
The blower makes this difficult to take off the belt.

Ah right, of course.

Charge light flashed several times then went off for the remaining 2ish miles to work. Sound remains though when car is idling. Where do I measure alt output?

Across the battery terminals.

Check it at idle and rev the engine to ~2000RPM and check again.

joshjwc9 · Apr 15, 2013

You guys have me so worried its just getting towed home. Voltage looks to be right at 14 at idle and about the same at 2k with me testing myself. I think she knew I've been looking at Miatas as a DD.

trinity_gt · Apr 15, 2013

14 VDC sounds okay to drive, at least electrically. Perhaps a bearing is on the way out.

Curious: Are you sure it's the alternator and not, say the smooth or grooved idler or tensioner pulleys making that noise?

joshjwc9 · Apr 15, 2013

I didn't risk it. Haha.

I'm more than positive it is coming from the rear most part of the alternator by me using a 1 foot section of vacuum hose and putting my head really close to the alternator. I'm probably going to replace all the idlers went I get the bracket off too, especially since I'd rather spend the money for peace of mind.

joshjwc9 · Apr 15, 2013

I ordered a heavier duty alternator from a manufacturer who I've seem several really good reviews from on eBay:
http://www.ebay.com/itm/FORD-MUSTAN...Parts_Accessories&vxp=mtr&hash=item1e78debcf4

Going to get some HD idler/tensioner pulleys from the Advance around the corner too.

I'm probably going to make my own thicker gauge wiring too, with say 2 gauge wire from the alt to the battery. Or pick it up from the local audio place. Do I need an inline fuse too?

trinity_gt · Apr 15, 2013

I had a problem with my 6G where that plastic piece that acts as the rear bearing support cracked and allowed the entire shaft and bearing assembly to move radially. It never made noise but I noticed it while searching down another noise... I wonder if the 6G doesn't like reverse-rotation as happens when used in a KB installation.

A bearing replacement and new tolerance ring are pretty cheap. But if you've already ordered a new one then never mind

joshjwc9 · Apr 15, 2013

trinity_gt said:
I had a problem with my 6G where that plastic piece that acts as the rear bearing support cracked and allowed the entire shaft and bearing assembly to move radially. It never made noise but I noticed it while searching down another noise... I wonder if the 6G doesn't like reverse-rotation as happens when used in a KB installation.

A bearing replacement and new tolerance ring are pretty cheap. But if you've already ordered a new one then never mind

I don't wait around

I may do just that and keep it. It is the OEM one BTW with all of these miles and I just put it up to wear/mileage/being in a boosted application. Now to take the blower off and support it so I can swap in the new one and new idler.

I see PA Performance sell a wire upgrade, can I just use some big gauge audio cable to upgrade it or do I need some sort of inline fuse?

trinity_gt · Apr 16, 2013

Definitely keep the old one around. Repair parts aren't expensive and it's good to have spares. I bought a black-painted high-ampacity PA alternator for mine but found the regulation to be terrible: lights would dim badly at idle and would vary in brightness with engine RPM, a sign the regulator wasn't up to par or something else was wrong internally. Shame because the black looked good under the hood. I ended up fixing the OE part and shelving the PA. I might try to fix the PA at some point. (I couldn't really return it because I took a grinder to the case as you need to do to make it fit in reverse for a KB car.)

I wouldn't bother with a wire upgrade unless you plan on drawing huge amounts of current from the alternator or the existing wire has corrosion issues or, for example, a bad crimp. What sort of electrical loads do you have (e.g. big stereo?)

joshjwc9 · Apr 16, 2013

trinity_gt said:
Definitely keep the old one around. Repair parts aren't expensive and it's good to have spares. I bought a black-painted high-ampacity PA alternator for mine but found the regulation to be terrible: lights would dim badly at idle and would vary in brightness with engine RPM, a sign the regulator wasn't up to par or something else was wrong internally. Shame because the black looked good under the hood. I ended up fixing the OE part and shelving the PA. I might try to fix the PA at some point. (I couldn't really return it because I took a grinder to the case as you need to do to make it fit in reverse for a KB car.)

I wouldn't bother with a wire upgrade unless you plan on drawing huge amounts of current from the alternator or the existing wire has corrosion issues or, for example, a bad crimp. What sort of electrical loads do you have (e.g. big stereo?)

Nothing really, just a deck and wanted to overbuild considering the opportunity to. Probably will be looking for a bearing kit too here shortly as well.

Alternator whine and battery flashing..

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