Need new alternator...DIY?

[vbrock1137]

Ok, so I just spoke to the dealership, who says I need a new alternator. Over the last couple years I've gone through 4 MB batteries, which the dealership keeps replacing for free b/c of parts warranty. Everytime I asked if the alternator was the problem and they've said no until now.

They told me $6-700, which definately more than I want to pay. From mercedesshop I can get a 115 amp for $215 or a 150 amp from a C43 for $380, which I would think might fit my car ('97 C230)...? The 115 amp seems like the better deal, seeing as it's still more than the alternator I have (90 amps I believe). I'm running 500W to my subs, but the lights never dimmed with the origional alternator, so I think 150 amps is overkill. Any comments, suggestions?

Also, most importantly, how difficult would this be to exchange? I am mechanically inclined and not afraid to do my own work, but I know nothing about alternators.

Additionally, I don't necessarily trust the dealership, is assessing the alternator as easy as checking the voltage output?

[martattack]

I would consider an alternator a DIY job.

Have you checked the voltage output of the alternator? What did it read while the car was on?




Essentially to replace the alternator, you slacken the Serpentine belt.

Disconnect the two electrical cables.

Unbolt the two mounting bolts.

Then it's free. To remove it, you will probably have to remove the lower splash pan and take it out from the bottom


Installation is reverse of removal. Don't overtighten the wire connection nuts. Retighten the alternator mounting bolts to about 30 lb-ft.

[vbrock1137]

No, I didn't get a chance to check the voltage. I just took it straight to the dealership once I got it jump started.

I'm gonna let the dealership replace the battery under parts warranty, then check the alternator myself. What voltage should be the lower limit of acceptable? 12v?

[Sulaco]

If the car is running it should be sending something like 12.4 or 12.6 to the battery. If it's only sending 12, then it's not charging the battery, and for those brief seconds you use the battery to start it, it's draining battery power. But, it then holds steady while the car is running because of the neutral charge of 12v.

[bc24]

Same exact thing is happening to my car and they never replaced under starmark. I have gone through about 4 batteries also. If I dont drive the car for about 3-4 days it dies...Sometimes I hate Mercedes....

[benzaddict]

Sorry Sulaco, but you're a little off. At idle you should see 13.2-14v. Much less and it's not charging well, or the battery is severely discharged. Any higher than that and your voltage regulator could be faulty. More than just a voltage test though, you'd need to do an AMP output test with some sort of load simulator. Shops use a tester, but if you're at home with an ammeter, you can turn on all accessories you can think of and the amp reading should stay positive.

Also, you guys should realize that when a dealership replaces your battery for free because of the parts warranty, they're doing you a favor and not screwing you over. They could keep your car and charge your old battery for a day until its ok, or jump it and send you on your way possibly leaving you stranded if you don't drive far enough to recharge your weak battery. It's just a better decision to replace it and if MB will pay for it instead of you all better.

BC24..... it sounds like you have a static draw, you should have it checked or check it yourself. Static amp draw should be no more than .030amp after about 20 minutes. That means that something is draining your battery after you shut it off-doesn't really have anything to do with alternator output. But it could be why you're going through batteries. I see you're in Bellevue, send me an email if you need help.

[Sulaco]

Yeah, I kind of knew I had those numbers wrong, but I've been sleeping 3 hours a night for a week.

Finals week. Hooray.

[Denlasoul]

True that benzaddict.

bc24, I have left my car sitting for three weeks and it started up fine, and that was before I got a new battery (my old one was fading out...long story). Something must be draining your car. Maybe one of your door latches is not working properly?

edit: Do you have an aftermarket stereo?

[jnolte]

i need a new battery where in WA st can i get a good one for cheap?

[bc24]

Hey, no the only thing I have aftermarket that is electronic are the 210 mirrors and there is no way that is what is going on. Benzaddict, thanks for the offer, I might take you up on it, haha.... I have been trying to get this fixed for about a year now and Barrier hasnt even come close. They told me they checked for a draw in the fuse box and have repeatedly found nothing....Any other ideas? Thanks for the help and I would meet up if you think you might have some ideas... Thanks again.

Brandon

[benzaddict]

Originally posted by jnolte
i need a new battery where in WA st can i get a good one for cheap?

I know this guy in Renton that has a kick ass shop called SG Motorsports, I'll bet he can score you one for cheap. But you'll have to get off your ass and call him!! lol

BC24-send me an email, I'd be glad to help.

[vbrock1137]

Any idea how much it would cost to have my current alternator rebuilt?

[jnolte]

Originally posted by benzaddict
I know this guy in Renton that has a kick ass shop called SG Motorsports, I'll bet he can score you one for cheap. But you'll have to get off your ass and call him!! lol

BC24-send me an email, I'd be glad to help.

will do ;)