Bad Alternator Replaced. Curious if used alternator is good

mperez0029 · Post by **mperez0029** » 03 Jan 2015, 17:14

Hello everyone. This is my first post, though I've read the forum many times to help with an array of problems for my 99 Volvo V70.

I'm looking for some information on bad alternator symptoms. What exactly are the symptoms on a bad alternator?

Recently, I was driving and the "generator not charging" light came on. I immediately checked the battery at an auto zone(battery was fine) and my car nearly died on the way home(dim lights, loss of power, dash warning lights coming on). I replaced the bad alternator with one from a pull-a-part junkyard.

The car runs and is driving fine with the used alternator from the junk yard, but both my headlights and dashboard lights dim when I start the car, and when I roll down or up or hit the window switches. Is this a sign that my alternator is nearing the end of its life?

Tomorrow I'm visiting auto zone and pep boys to do an alternator check.
I'll also be cleaning the terminals on the battery(advice on this would be great).

Any input on other things I should check? Specific values? Cleaning the terminals? Is the light dimming normal on my model?

All help is greatly appreciated!

Post by **Ozark Lee** » 03 Jan 2015, 18:31

In most cases a bad alternator will illuminate the battery indicator on the instrument panel.

I have seen a couple of alternators in my life that actually generated power but not enough to keep the battery charged that didn't light the alternator light but those have been few and far between. The dimming lights that you describe are often due to a bad battery cable rather than a bad alternator. The B+ cable that branches off of the main battery terminal and goes to the fuse box is a know problem area on these cars.

The chain auto parts stores should be able to load test your alternator while it is installed in the car and let you know how it is doing. If the test comes up with a few Amps under the rated output of the alternator I wouldn't lose any sleep over it. Also keep in mind that the auto parts store is much more interested in selling you an alternator or a battery than they are in actually diagnosing your problem. Not that they are all total crooks but the bias is there toward recommending a replacement part since that is their primary business.

...Lee

1998v70xcbill · Post by **1998v70xcbill** » 04 Jan 2015, 08:07

I have a 98 v70xc, I was looking at the 95-97 service manual. The alternator has replaceable brushes and regulator. Easy to replace, if you have access to back of alternator.
I used to spend about $30 for replacement voltage regulator for a bosch mercedes alternator (What is a good source for a volvo voltage regulator?
The Brushes do wear out. How many miles? Diodes in the alternator can also go bad.

Testing wiring:

Turn on large load, (high beams, fan high, heated seats)
Run engine at 2000 RPMs, look for voltage drops greater than 0.2 volts

Ground: "Alternator case" to "battery ground"
+12 "Alternator +B" to "battery +12"

Testing current: Run at 2000 RPM, Load @ 12.0v (using variable resistor) Measure current
The service manual listed different currents for different alternator sizes.

My Question is: Does my 1998 v70xc have a replaceable "voltage regulator", and how hard to replace with the alternator on the car?

Bill

1998v70xcbill · Post by **1998v70xcbill** » 04 Jan 2015, 08:14

I just answered my own questions.

https://www.matthewsvolvosite.com/forums ... =1&t=51957

searched "98 V70 Voltage Regulator"

Post by **Ozark Lee** » 04 Jan 2015, 08:26

Glad we could be of help!

It is kinda scary, It seems that most answers actually are here or linked from here but it can be tough to sort through the posts to actually find the answer.

...Lee

joe_pinehill · Post by **joe_pinehill** » 04 Jan 2015, 08:51

When I've had alternators go, I have never had the time luxury, all I have done is go to the autoparts store with one in stock and remove/replace the old one. I even did one in a parking lot on my 240.

Post by **erikv11** » 04 Jan 2015, 09:25

1998v70xcbill wrote:... My Question is: Does my 1998 v70xc have a replaceable "voltage regulator", and how hard to replace with the alternator on the car? ...

This one has been posted about a lot recently, you need to be careful about which regulator you buy, e.g. this post and links therein:
https://www.matthewsvolvosite.com/forums ... hp?t=63879

mperez0029 · Post by **mperez0029** » 04 Jan 2015, 15:34

Ozark Lee,

Thanks for the prompt response. I was reading 13.6 Volts today at autozone with everything on. I'm going to look towards cleaning the terminals and do some research on the b cable. Maybe I'm being overly cautious, but I like to prevent things before they happen haha.

1998v70XCBill,
I'd love to rebuild my alternator but I can't find a suitable kit, like erikv11 mentioned the specifications on the regulator can vary. A few sites had alternators that they claimed to be compatible but had various amps and volts. A risk I'm not willing to take. Oh and I did get an alternator test at auto zone but car was idling with radio and heater on, no seats and not at 2000 rpm. Will def try at pep boys in the morning.

Thanks for all the advice folks! I did manage to change out my thermostat easily today and heat and gauge are on point. I'll update this soon and see if I can't do more research into the light dimming

Post by **cn90** » 04 Jan 2015, 15:51

VR for 1999+ model is below. Make sure you buy the correct Bosch VR:

Best is to rebuild the alternator. The slip rings should last some 300K, so if you are at 150K, all you need are:
- VR as mentioned
- Front (larger) bearing
- Rear (smaller) bearing

That is all, many people have rebuilt their Bosch alternator successfully.

Post by **bmdubya1198** » 04 Jan 2015, 16:11

You could always get the alternator tested at Autozone.