alternator questions

alanbobalan · Post by **alanbobalan** » May 22nd, 2006, 1:39 pm

okay, so i tested the alternator and i know it's starting to get weak. with the engine running and all the accesories off, the battery voltage is 14.2v. with the engine running and all the accesories on (lights, brake lights, turn signals, stereo etc.), the voltage drops to 12.92v.

correct me if i'm wrong, but this would indicate a weak alternator.

now for my dumb question....

i have the alternator disconnected but i can't seem for the LIFE of me to be able to pull it out of the car. there is simply just too much junk in the way and it won't come up and there is no room for it to fall down. looks like an ac line that's in the way.

so basically i just need to know what else you guys disconnect in order to pull the alternator. once i have it out, i'm going to open it up and figure out what's wrong. then i'll decide whether it would be better to rebuild it or buy a new or rebuilt one.

thanks guys

alanbobalan · Post by **alanbobalan** » May 22nd, 2006, 1:40 pm

i almost forgot.... i have a 92 mx-3 with a 4 cylinder engine. thanks!

ariesdude · Post by **ariesdude** » May 22nd, 2006, 5:42 pm

When i got mine out - i just twisted and turned till it came out through the top - i took the charcol canister (the big black plastic cylinder) off to give me more wiggle room.
Some people have had success with removing the exhaust (cat) and dropping the alt down through there.
Some people have removed their right wheel and have had some success.

Also low voltage may not necessarily mean bad alternator - it could also be a bad battery and/or bad ground. (In my car some dumba$$ had replaced the brake lights with higher wattage ones - so it almost stalled everytime i braked with headlights on). Usually the voltage regulator in the alternator goes bad - and a replacement regulator is not available i think.

If you are replacing the alternator try getting a v6 alternator - they are rated 20amps more than the 4 cyl and fit in the 4 cyl block - almost plug and play. (search for "alternator swap")

alanbobalan · Post by **alanbobalan** » May 22nd, 2006, 9:16 pm

thanks for the reply.

well, i unbolted the exhaust and the old alternator popped right out with no problem.

i bought a remanufactured bosch alternator and installation was a breeze after taking the old one out.

now i did another voltage test and it STILL drops. with all the electrical accessories on (high beams, brake lights, turn signals, ac, blower motor, wipers, defroster, etc) the voltage dropped as low as 12.5 volts and STAYED there!! is this normal? correct me if i'm wrong, but shouldn't the voltage drop and then come back up to 14 volts with the engine running? i'm new to all this electrical mumbo jumbo.

i am starting to suspect my old alternator wasn't as weak as i thought. baaah!

a month or so ago, i did a hydrometer test and a voltage test on the battery and everything checked out ok. the specific gravity of the electrolyte was to specifications and the battery voltage was around 12.4-12.6 volts. i then cleaned the battery and the tray with baking soda and water and installed a new ground strap and cleaned both terminals.

also... last week while i was at school, my instructor helped me perform a load test on the battery and everything was normal.

i don't know how old the battery is and the hold down bracket is missing. the previous owner used a bungee cord to hold down the battery. but i don't see how that would affect the alternator not putting out enough current.

please help! maybe this is normal, maybe it's not. i really just don't know.

ariesdude · Post by **ariesdude** » May 22nd, 2006, 11:31 pm

When you use ALL electric devices in the car the voltage is going to drop a bit - considering that your alt only puts out 65 amps. If you are replacing the alt anyway get an alt from a v6 model - they are rated for 90 amps. But still the voltage shouldnt drop to 12.5 i guess - that could be a lot of stress on the battery.

I would say - Go for a ground kit - the wiring and the ground points on your car is 14 years old! It is almost certain that everything is corroded/rusted and generally not making good contact. So first thing would be to clean up and maybe sand all the ground points in the chassis. And then add ground wires direct from the -ve terminal to the chassis and engine/manifold/tranny. You will see a huge difference in the electrical system and a slight engine performance improvement. If that doesnt help then you need to go hunting for compromised wiring somewhere in the system.

Here's a link for making ground wire kits
http://www.clubprotege.com/wil/howto/groundwire/

or you could buy a cheap one off of ebay.

Grants · Post by **Grants** » May 23rd, 2006, 2:30 am

12.5V sounds pretty normal under such a big load at idle. Hold it @2500 revs for a couple of minutes and see what the voltage reading is. It should come up a bit but don't expect anything near 14V.

You gotta keep in mind that if the alternator was "tired" it wouldn't put out the current (amps) so the battery would go flat. Its obviously doing that ok. The regulator is what tries to keep the voltage level, and 14 volts @ no load down to 12.5 volts at a very big load would be expected and acceptable.

alanbobalan · Post by **alanbobalan** » May 23rd, 2006, 4:05 pm

what other tests can i perform on the alternator? (maybe i should have asked this BEFORE i ran out and bought a new alternator.... oh well)

one thing i forgot to think about is that the voltage never dropped below battery voltage (12.5V-12.6V). correct me if i'm wrong, but would that imply that all the current the alternator generates is simply getting "used up" by having all the electrical accessories running simutaneously?

like i said... i'm a newbie to automotive electricity and electronics. someone please enlighten me

alanbobalan · Post by **alanbobalan** » May 23rd, 2006, 4:11 pm

one other thing i forgot to mention in any of my previous posts:

with the OLD alternator, the charge light used to come on after starting the engine with the old alternator. that's when i started to suspect it was weak. i did the voltage test (mentioned above) and i thought this would confirm that, but i don't think i investigated the problem throughly. at least i won't have to worry about a faulty alternator anymore!

jschrauwen · Post by **jschrauwen** » May 23rd, 2006, 5:56 pm

I had somewhat similar problems with my alt. Rather than taking a chance on an unknown rebuilt from a store I took it myself to an alt specialist who not only be a complete rebuild but upgraded it to 120 amp service. The intermittent problem i was experiencing with it for months was a wire contact within the casing itself and it just got completely corroded and was on it's last legs. Now with a completely newly rewound and completely overhauled alt, I should see another 10+ years of alternator problem-free driving. It cost me a few extra bucks but I know where to take it back to if problems occur in the future. The upgraded package included some Millennia internals.

ariesdude · Post by **ariesdude** » May 23rd, 2006, 6:12 pm

First, connect a charger and get the battery upto full charge - If the battery is more than 3-4 years old - replacing it might be a good idea - it might have been weakened by your old alt. Usually it is recommended to replace the battery when replacing an alternator.
Then, try adding a ground wire kit and measure again.....

I just measured in my car with the headlights, defrost, radio (with subwoofer), heater fan (full speed), brake lights, interior dome lights and someother things on - the lowest reading i got was 13.4 (when i tried to use the aftermarket power window stuff. Otherwise it would momentarily dip to 13.8 and then quickly get up to 14.4 or more. I have a 90amp V6 alternator and a ground wire kit.

Edit: I just noticed that you have your battery tied down with a bungee cord - a bungee cord stretches under strain which means that battery is dancing around in the bay when you are driving - that is certifiably not good for the battery or the terminals. Besides all that - it could be a fire/explosion hazard - So that would be another thing to fix immediately.

alanbobalan · Post by **alanbobalan** » May 23rd, 2006, 7:08 pm

first and foremost, big thanks to everyone for their 2 cents regarding my alternator issues!

well, i drove the mx-3 to school today (60 miles both ways) and i can confidently say that it runs and idles alot smoother. overall it's alot more fun to drive.

the v6 alternator swap sounds interesting, however in my situation i just need to keep the car running as good as stock. it was recently involved in a hit and run in which someone smacked into the back of it and took off while it was PARKED in front of my house. let's just say it's not the prettiest mx-3 out there, but it may see an overhaul sometime in the distant future.

however, a ground wire kit sounds like a good investment for the future. or at least "cleaning up" some of the old ground connections. i also heard something about grounding the fans straight to the chassis. can anyone elaborate on this?

i know the battery is still good because i used a load tester to test it. i also checked the electrolyte level and the specific gravity. the only thing wrong with the battery is the missing hold down bracket. although a new battery couldn't hurt anything.

ariesdude · Post by **ariesdude** » May 23rd, 2006, 9:40 pm

alanbobalan wrote:the v6 alternator swap sounds interesting, however in my situation i just need to keep the car running as good as stock.

my old alternator was going out and i had a choice between $150 oem reman alt or a $30 junkyard alt from a v6 - needless to say i chose v6 alt and made it work.

alanbobalan wrote:i also heard something about grounding the fans straight to the chassis. can anyone elaborate on this?

pretty much same principle as ground kit - the fan motors take up a lot of startup current and the connectors and ground points would have corroded to hell by now. So if you provide an alternate direct path to ground (splicing in as close as possible to the fans) the fans will start a bit more easily.

alanbobalan wrote:i know the battery is still good because i used a load tester to test it. i also checked the electrolyte level and the specific gravity. the only thing wrong with the battery is the missing hold down bracket. although a new battery couldn't hurt anything.

Well, then i would probably get it charged overnight so that the new alternator doesnt go down the drain.

Grants · Post by **Grants** » May 24th, 2006, 12:29 am

Well, then i would probably get it charged overnight so that the new alternator doesnt go down the drain.

120 miles of driving should be more than sufficient to charge it. Even if it was flat, I don't see how it could make the alternator fail.

alanbobalan · Post by **alanbobalan** » May 24th, 2006, 3:41 am

Grants wrote:120 miles of driving should be more than sufficient to charge it. Even if it was flat, I don't see how it could make the alternator fail.

ditto. the battery getting charged has never been an issue. at this point i have pretty much figured out that my old alternator probably wasn't faulty, just a tid bit weak. the charge light would come on after starting the vehicle in the morning. then a good rev up to 3,000 rpms turned the light off and away i went. i guess i just like to stay on top of things

i just need to make sure i get my hands on a hold down bracket and from there i'll investigate the ground wire kit further.

jschrauwen · Post by **jschrauwen** » May 24th, 2006, 3:52 pm

alanbobalan wrote: the charge light would come on after starting the vehicle in the morning. then a good rev up to 3,000 rpms turned the light off and away i went.

Those were the first signs of degredation that I found on mine. It got progessively worse after that. Dependant on use , weather, temps etc, will have a factor as to when exactly it will finally give out. It's someting that usually will never fix itself or go away. Time will tell.