Do I go ahead and replace the alternator? Should I be suspecting something else?

[MNG8]

It's been a rough month car-wise in our household and I'm trying my best to put an end to it without crushing our bank account, but need your collective genius to help me avoid an expensive Easter egg hunt. A little background: To start the month, the tranny in my wife's BRAND NEW Jeep GC went out at just 1600 miles. Sucks, not happy with Chrysler (should have stuck to GM), but warranty covered the fix and 2 weeks(!) later she's back up an running. Literally same day the Jeep dies, I'm cruising home and get the flashing check engine light on the STOCK 2009 G8 GT after a little bit of spirited acceleration. I slow down and get a rough shaking from the engine. Limp it 2 miles home, read the error code and see its misfiring in a cylinder (7). I change the spark plugs hoping that resolves it, but no luck. I also change the belts while I am digging around the engine since I am at 93K miles and still on original belts. Bring it over to the local dealer and they repeat my work checking the spark plugs for the first hour of labor, find they're like new (ya, that's why I told them I just replaced them. They have only 3 miles on them! :facepalm2:). Tell me I'll have to cough up more $ for them to keep digging. I point out again I have a warranty, they come around and agree to keep working on GM's dime. Turns out I have a collapsed lifter. They replace, and next day I am back in action. I smell burning coolant over the next few days, but figured it just was lost fluid left over from the repair and levels look good, and that it'll burn off shortly. About 200 miles later I start hearing a whining coming from the engine bay. Not too noticeable unless you're inside the cabin of the car. Changes pitch with RPM, but no change if I turn on/off the A/C. Figured belts might be aligned poorly, so I check it put it appears OK to me. 200 miles and a week or so later, the whining is now getting louder and now you can hear it from outside the cabin. Its definitely a whine, rather than a squeal/chirp if that makes sense. And its loud enough others are taking notice of it too. Then the "SERVICE CHARGING SYSTEM" warning appears. I drive 4-5 freeway miles home, turn off the car. Try and start it back up and nothing. Not even the faintest hint of turning over. I hook up the battery to a trickle charge. Few hours later, starts up fine. No warnings, no DTCs. Another week later sitting idle at a drive thru, I get the "Battery Saver Mode" warning. A/C shuts off and I drive home. Battery charge in engineering mode reads 0.7%. Put it on the charger for couple of hours, drive it 5 miles or so and "Battery Saver Mode" comes back on. Engineering mode reads 1.5% battery charge. Ouch. Engineering mode shows me voltage is reading 11.7v at idle, but at about 2000rpm it jumps to 12.5, then drops to 11.3, then to 13.2, then 11.8 and levels out there all withing the span of about 10 seconds at ~2000-2500rpm. Headlights go bright, dim, brighter, dimmer as I'm stepping on/off the throttle. I grab a new H7 battery from Walmart, put it in. 25 miles later, no surprise I am sure, I get the "SERVICE CHARGING SYSTEM" followed a few minutes later by "Battery Saver Mode". Engineering mode read 73% battery life. Voltage at 11.5v, pretty consistently now though (except at start up it drops to 9.8v then recovers to ~11.5). I take off the serp belt (not AC belt), whining stops 100%. Replace belt and the whine returns. And this is where I am at.

I've been digging through the forums per usual to find the solution to my problem (Note: You all are truly amazing. This forum not only sold me on getting the G8 years ago, its been a godsend when it comes to my questions), and from what I understand in my limited car knowledge I likely need a new alternator. Correct? I'm just hesitant to start replacing parts willy-nilly and since I have not seen the "ALTERNATOR" light in the DIC (except when I removed the serp belt), I'm just not 100% the part's needing to be replaced. What else should I check before shelling out the $300-400 to get a new alternator? Or does this sound like it might be something else I should be checking?

Thanks for any insights you all can provide!

[STL_G8GT]

I don't know what else would allow the new battery to go dead in such a short period of time...

[-Ray-]

Take the car to autozone or the like. They can test the alternator. The regulator or diode package most likely went bad.

[Napalm]

can you separate the regulator from the alternator on the G8?

also I have to assume you've done this but. take off the alternator connectors and check them for cleaness, and check your car's body grounds for the same. although I suspect they are OK. you might have a corroded terminal that is prevently good current flow.

[MNG8]

Thanks, everyone. I have not checked the alternator connectors, but that's a good idea before I get in too deep. If all looks ok there, I'll stop on over to the autozone and have them test the alternator. Thanks, everyone. I'll let you know what I find.

In the meantime, do you suppose its okay to drive a bit? I charged up the battery last night so its back to 99%, so it should have a charge to get around a bit and we wouldn't take it across the state, but do kind of need it for a day or two before I tear into it too much.

[Doug Hilliard]

You might check the main ground which is on the front of the passenger side head - large braided wire; the stud comes out of the front of the head and faces toward the front of the car. I can't imagine it running well if it's loose but I suppose it's possible they didn't tighten it good so the system is not quite up to snuff. I doubt this is it. I don't know about driving it as I'm not sure how long it will run on battery power; I would expect a half hour or more for sure but don't have any experience with that situation really.

[AuuuSSSIII YA' LATA]

I'd definitely would check your ground alternator wiring first, through my experience here at the dealership, sounds a little suspicious it's so intermittent and someone was just in there. If u wouldnt have said a word about the first time the car was in I would have just agreed and said throw an alternator in it also.

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[AuuuSSSIII YA' LATA]

......power ground (,) and alternator.....I'm not a phone guy sorry

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[MNG8]

Well, I wound up replacing the alternator as the original was bad. I replaced it with one from Pace and they were great about getting me the right part. I've got a bit of vibration/buzz in the power steering pump now as I had to remove it to get to the alternator, but I likely just need to torque up the bolts to spec and I am hopeful that will be resolved. Thanks, everyone!!

[texn884]

Wow what a saga

[MNG8]

It's been a long couple of months! Glad to put it (and some burnt rubber) behind me :devil: