2008 S60 Can alternator cause parasitic drain on battery?

veektor · Post by **veektor** » 26 Feb 2018, 08:21

Hello, this is my first post, so a brief into is probably in order. I'm adding headers to the post to help navigate my wall of text.

INTRO:
I'm a brand new Volvo owner. Well, 2008 is not exactly 'brand new', but it's a first Volvo for me. I cut my big-boy teeth on a Subaru Forester when it spun a rod bearing and I chose to rebuild the engine, rather than junk the car. Paying someone for the repair was not an option, and after a year of struggle I got that Foz back on the road. That gave me the courage to take on cars that most people consider 'risky' or 'expensive to repair', or generally distressed. So far I've had great luck with my E46 BMW, and mixed bag with 1990 Toyota Celica, while generally happy with my '96 Jeep Cherokee. Jeep and Toyota have given me a new perspective on rust. While I can see myself eventually tackling the floorboards on the Jeep, the overall rust condition on Celica is beyond my abilities at this moment. That rust is what brought me to Volvo. Every Volvo I've got a chance to examine up close seemed to resist that awful cancer, and I figured I'm already cozy with FCPEuro guys from working on BMW, why not try my hand at Volvo?

I chose this particular S60 because it was cheap ($600), had good body, two keys, but also because I thought it would be easy to fix up. This forum has been incredibly helpful in my research, and led me to believe that the valve knocking sound is probably caused by oil starvation due to failed oil sump gaskets. I am placing an order for the oil sump gasket kit, as well as the timing belt+WP combo, because I would like to avoid doing a head job, if possible.

ALTERNATOR:
Previous owner also warned me about parasitic drain on the battery. When I got Astrid home (that's her name now), I topped her off on oil and ran gently just to read OBDII codes and see if there are any other obvious problems. Got P0302 (Misfire cyl 2), P0027 (Exhaust valve solenoid), and P2195 (O2 Sensor Lean). The dash display reads "POWER SYSTEM SERVICE URGENT" and the battery symbol is ON. After that warm up, I shut her down, and heard a tinny buzzing in the engine bay, which was coming from the alternator. I noticed a "REMAN" sticker on the unit, unplugged the negative cable from it, and the buzzing stopped. I am monitoring the battery voltage overnight to see if that helped.

I've found discussions related to alternator buzzing and replacing of the regulator unit. If alternator is the root cause, I don't mind swapping it. My question is broader in nature: should the alternator even be connected to the battery when ignition is OFF, and keys are out? I don't want to start replacing the alternators just to realize after 2 or 3 of them that there is a module or relay that is supposed to cut the alternator off from the battery with ignition OFF. I would like to see some diagrams if possible, or hear a reasonable explanation from someone with experience.

Post by **abscate** » 26 Feb 2018, 09:59

Definitely can. If a diode shorts to ground or to no resistance (a bit unusual but does happen) it will drain the battery in a few hours.

Post by **mrbrian200** » 26 Feb 2018, 12:19

The alternator is permanently connected to the battery by design. There are a lot of things on a car that don't get disconnected when the key is turned off that basically enter a reduced functionality 'sleep state' similar to turning off a TV with the remote. Any of them can drain the battery if they develop certain types of internal failures.

veektor · Post by **veektor** » 26 Feb 2018, 16:00

mrbrian200 wrote: ↑26 Feb 2018, 12:19 The alternator is permanently connected to the battery by design. There are a lot of things on a car that don't get disconnected when the key is turned off that basically enter a reduced functionality 'sleep state' similar to turning off a TV with the remote. Any of them can drain the battery if they develop certain types of internal failures.

Thank you, this is why I was looking for Volvo-specific expertise. When I first discovered the hum in the alternator, I did a quick search, and the top answer was on a Corvette forum. It sounded reasonable that alternator should get disconnected from the battery, but I figured things can work differently on post 2000 Volvo cars than 80s Corvettes.

I already made a list of things to look for at the junkyard, mostly odds and ends of nuts and bolts, but the alternator is at the top.

Post by **mrbrian200** » 26 Feb 2018, 16:23

Alternators are one of those parts where the basic functional design doesn't vary all that much between makes/models. Something read on a Corvette forum with regard to diagnostics on a potentially failed alternator would also apply to a Volvo in most cases.

Post by **abscate** » 27 Feb 2018, 10:52

I doubt there is a car maker left in the world who makes their own alternators - they probably source from Bosch, Delphi, Toyo Industries and a couple of others. They all are little boxes and they all look the same.

Post by **RickHaleParker** » 27 Feb 2018, 11:10

A shorted Diode can cause both Alternator hum and parasitic drain. Disconnect (unload) stopping the hum confirms the Alternator assembly is defective.

veektor · Post by **veektor** » 28 Feb 2018, 07:22

It's a good thing I don't have time to wrench on the car this week because that forces me instead to research the alternator replacement procedure. This means I have a few new questions.

1. FCPEuro video advises to drain coolant and remove upper rad hose. I see some other DIYs where that hose remains in place. I'll have to think about that a little. I was going to put off T-belt and Water Pump replacement until I was sure the oil sump gasket kit resolves my valve slapping issue. I may just move it higher to the top and tackle with the alternator, while coolant is drained. Opinions?

2. Re: Alternator Amperage. There are two versions: 140A and 160A. How do I know which one is right? Because the current unit was replaced by PO, I am inclined to be suspicious of it being selected correctly in the first place. Any other way to tell which one is required, other than "look on the back of original unit"? I also came across discussion that mentions alternator change after 2005. This is very important for me to know before I head out to my junkyards and get all excited about all those Volvos on the lot.

3. I seem to recall one of the posts mention that on these units the voltage regulator was replaceable, but rectifier was built-in with the generator. If diode failure is indeed the problem, it would be in the rectifier, not the regulator, which means I can't just replace the regulator itself. It could be complete nonsense, of course. Does anyone know for sure?

EDIT: I searched after posting and found this about regulator vs. diode bridge: viewtopic.php?t=51058
I guess I can at least start by pulling out the alternator and test the modules. I don't mind getting into the weeds like that if I can save some money. I would rather spend dollars on consumables and things that cannot be easily repaired, i.e. suspension.

veektor · Post by **veektor** » 28 Feb 2018, 11:22

Well, shucks. The year 2008 sounded good when I was shopping around for this Volvo project, but my enthusiasm is waning after searching for P2 Volvos at the junkyards, and seeing they are mostly 2001-2004. I'm going to have to stock up on some patience with this car. Or cash.

Post by **RickHaleParker** » 28 Feb 2018, 14:54

There are two different Alternators for the 2007 S60. A 140 Amp and a 160 Amp version.

140A is Volvo Part number 36012358 and has been replaced with Volvo part numbers 30658085, 30667894, 30667787.
160A is Volvo Part number 36050266 and has been replaced with Volvo part numbers 30658087, 30667788, 30667895.

Go back and look for one of the newer 160A Alternators. You can find then on 60, 70 , 80 and 90 series Volvo.
You should be able to find one at one of the two Pick-in-Pulls in KC for $16.99.