2008 M35 Alternator Replacement

[Ronjon17]

Hi there,

My brother has a 2008 m35 base model. Recently was having some start issues, battery was replaced less than 2 years ago. He took it to the dealer (usually a dumb idea IMO, but it is my brother), who told him his alternator is bad. Question is they are asking $900 for replacement -- seems a bit high to me (he lives in Houston, TX).

I'm a DIY'er and am visiting him this weekend anyways -- can anyone speak to how difficult it is to swap out an alternator? Any DIY articles? Also, any basic tests that can be done with a multimeter to make sure the dealer isn't trying to pull a fast one? Seems like a car that's only 5 years old shouldn't have this issue (he's out of warranty, unfortunately).

I saw on InfinitiPartsUSA the alternator is going for $320 -- some other third parties going for around $100 -- so just seems like an alternator is a pretty easy swap out (i've done it on other cars) and the dealer's labor charge is excessive.


Any and all info is sincerely appreciated.

[Larz]

Welcome Ronjon and sorry to hear about your brother's issue. I haven't had to replace an alternator yet, but I agree that it can't be too terribly difficult and also agree that you may not need to use soley Infiniti parts.
There is an FAQ thread on this site with many DIY projects, but I was unable to find one for the alternator. You may want to message 'Steve the Tech' regarding this project.
Also, if you replace the alternator, maybe take a few shots with your phone as you go? We don't have a DIY for this yet, and it would be a nice addition to the list.
Wish you best of luck!

[DeanM45]

I find it hard to believe that the alternator is bad based on starting issues. Check the battery terminal connections (should be clean and tight).
If that is good, run it over to Autozone (there's a pretty good one right off of Westheimer down a bit from the Galleria -- I used to live in Houston) and have them do a test on the alternator and battery.

If indeed the alternator is bad, you remove from underneath the car. Remove the engine undercover (14 bolts if I remember correctly), alt/power steering belt, one clip connector, one connector (nut), and three bolts. Easy job. I have a M45 but I have messed with 35's as well.

[TDot]

So my battery is about 2 yrs old as well...at most 3, and when I start the car seems to be starting fine for a split second, then all of a sudden it seems like it's about to die for a split second like there is a power drain, then it kicks in. All told this sequence is 3-5 seconds. Is this an alternator issue?

[DeanM45]

No. I'd bet 90% battery and 10% battery cables. If the car sits for a few days does the battery go flat? If so, then definitely the battery.

[BlackCat81]

All data labor time for the alternator is 1.7hrs. It's not hard, but I can't imagine it being fun on your back in a driveway.

[TDot]

No. I'd bet 90% battery and 10% battery cables. If the car sits for a few days does the battery go flat? If so, then definitely the battery.

The car is behaving oddly. If I leave it overnight it starts up right away with no issues in the morning. But if I drive and park for 20 min or so, that's when it gives that laborious start...every time. I tested the battery and it's 11.6V at rest and 13.5V running.

[EdBwoy]

...
The car is behaving oddly. If I leave it overnight it starts up right away with no issues in the morning. But if I drive and park for 20 min or so, that's when it gives that laborious start...every time. I tested the battery and it's 11.6V at rest and 13.5V running.

Sounds like some sort of charging issue. How is your alternator belt in terms of cracks and tension?

[DeanM45]

Battery should be 12V minimum at rest. Heat builds up resistance so there is a larger load on the battery when restarting after only 20 minutes (heat soak). Battery is on its way out.

[BlackCat81]

No. I'd bet 90% battery and 10% battery cables. If the car sits for a few days does the battery go flat? If so, then definitely the battery.

The car is behaving oddly. If I leave it overnight it starts up right away with no issues in the morning. But if I drive and park for 20 min or so, that's when it gives that laborious start...every time. I tested the battery and it's 11.6V at rest and 13.5V running.

It should also be around 14.2 running, so it's definitely doing work to try and charge that battery. 11.6v is low, but voltage isn't what starts a car, amperage is. I'd put a battery in it and go from there.

[TDot]

Agred that the battery needs to(should be) be replaced, but as far as the heat soak, isnt that more of a starter issue. Belts are good, changed them yesterday.

[TDot]

Found this interesting, thought id share.
http://youtu.be/Oi8sUE9XCgA

[DeanM45]

Agred that the battery needs to(should be) be replaced, but as far as the heat soak, isnt that more of a starter issue. Belts are good, changed them yesterday.

Yes about the starter but that is the point -- with a hot starter (more specifically starter solenoid) more current is needed to spin the starter. A "weak" battery will have trouble at that point. Plus as the battery heats up the internal resistance (between the plates) also increases. I have seen many batteries that show good voltage (12.4V+) but that could still not start the car because there was not enough current available to deliver the "normal" voltage that the battery showed due to plate damage.