Alternator: DIY or not?

[Jesda]

From the 1992 Q45 FSM:



Should I do this myself or pay a shop? I'm still getting the funky idle. I replaced the battery and negative cable and both terminals and the symptom went away for a few days, but came back. I have to get on the highway for a while to keep it from hiccuping and sputtering out when I'm driving around town. "Low battery charge" is displayed on the warning screen when the idle starts fluctuating. Already cleaned MAF and connector, TB, CAS connector, TPS connector, replaced fuel filter.

70% sure its the alternator, since this is a used one that was installed in 2001 by the last owner.

What are the odds of me screwing something up? I dont exactly know what the manual means by "Remove radiator bracket" and "Remove AC pipe mounting bracket" and "Remove PS cooler pipe mounting screws."

[squeefoo]

From what I remember it looked like it would come out the bottom easier. Though I've never had to change one yet.

[911/Q45]

Take it to an auto electric shop to be sure it's the alternator before you spring for one, then do it yourself with a replacement from Joe.

[Jesda]

Can the alternator be tested without removing it?

[1992Q45A]

Quick thread Hijack:

911/Q45, you have the same brakes as I do.. Do you have the stillen brake lines on them?

[squeefoo]

Can the alternator be tested without removing it?

As per the other thread for test AC: less than 100 mv AC to test diodes. Amperes: Req's special expensive tool

[IvoryJ30t]

what you need is a clamp on ammeter.

they are on the expensive side for just a single diagnosis. the current the alternator puts out is overload for a digital multimeter.

the clamp measures the current flowing through the alternator positive wire.

i forget how much mine cost, i think it was 300 or something.

[Altiman94]

I have the answer to your question jesda. Take your car to advanced auto, or any auto parts store for that matter. Tell them you need your alternator checked and its still in the car. They can check it while its in the car with the car running. Simple as that. If it's bad, order a new one while you are there and install it that day if its in stock.

[Jesda]

I'm 99% sure this is alternator related, but I wanted to know more (electrically speaking) about what causes this.

I was driving to school this morning masochistically joking to myself "Ha ha, wouldnt it be twisted if my Q died too?" I noticed this morning when I started it up it had to crank a bit longer to get started. I got to school, parked, went to my 75-minute class, and came out to start the Q and it was dead. It was the same symptom as when you try starting with a weak/dying battery -- sometimes it cranks and sometimes you hear a "tick tick" sound like its completely dead.

I turned off the AC, radio, closed the door (to turn off interior lights) and cranked it about a dozen times (with brief breaks in between, didnt want to kill the starter) and finally it started. I got home (my drive home is 9/10 of a mile) and sat in the driveway. I turned on the high beams, AC, radio, put it in drive, and it wouldnt die. I shut it off, left the beams on for a minute, started it up, and it was as if it never had any problems.

This battery is 3 days old, as well as the negative cable and both terminals.

Now... here's my question. Why did it start up at all? And why did the starting problem go away after I drove home?

What role does the ground on the negative cable play? I assume the ground is the bracket attached to the negative cable that screws into the body.

Thanks!

[pito11213]

Since the battery was fresh it probably got charged enough to hold the cars electronics for a minute. Hence the reason why the car didn't shut off with all the electrical pull. There are some good testers that will show if the battery is bad or if the alternator is bad.

You can try autozone but I personally cant stand them for any diagnostic's.

Sounds like a bad alternator in general though.

The ground is very important since without that the electrical current cannot be carried. You need a start and a finish for DC (Direct Current)

If they are old you might as well as to replace the two battery terminals. But get the alternator tested or the next time you stop at a light you will find out the hardway.

[pimpingurz]

i agree, autozone does do it for free though.

[Jesda]

So I went to Autozone and had them test it. The idle started fluctuating, and as it did that the charge level on the meter dropped down to just below 12 volts. The monkey with the meter told me it was fine. No offense to Autozone employees, this guy was a freaking chimp.

Anyway, I left and went to an independent shop my parents take the company vehicles to. They hooked up a similar device and did some more thorough observations, with and without AC, headlights, etc. At idle in park it was barely sufficient, and only under acceleration was it enough. In drive the idle started fluctating again, until the headlights, AC, and wipers were turned off. The more electronics were used, the more unstable the vehicle was.

The conclusion I made was that the tired old alternator was just that... tired and old. I was quoted $680 parts and labor.

This is going to be one ugly DIY job.

-Jesda

[Rex]

Am I the only one that thinks Jesda + DIY = trouble?!?

I have to give him credit for even contemplating taking on this task, now if he does it, I'll nominate him for DIY'er of the month (a prestigous honor that does not yet exist)

[Jesda]

Am I the only one that thinks Jesda + DIY = trouble?!?

I have to give him credit for even contemplating taking on this task, now if he does it, I'll nominate him for DIY'er of the month (a prestigous honor that does not yet exist)

I think its trouble too. Though it really seems like a matter of just moving all the crap out of the way.

Hopefully if there's time I'll make it out to Wes's place where I'll have some help and something better than a $20 tool set from Wal-Mart. I'm still trying to convince the parentals to pay for it all, wish me luck!

[Rex]

Wrap hand in large bandage and try to "fix" one of the office PC's. Then when/if they ask, say just seeing if I'll still be able to work on the office PC's when I bust up my hand working on my car .

(you do know that was all in good fun, right)

[DAEDALUS]

Though it really seems like a matter of just moving all the crap out of the way.

That's only part of the job. You have to remember the order to put all the stuff back, know how to install it, and not break any of it. Replacing the alternator is a deceptively frustrating job. Much more 4-letter words used then when doing the fuel pump or the struts.

[Jesda]

I purchased an automatic charger today from CarQuest for $60 (okay, Mom did) and ordered an alternator from a 92 Q with 106k for $39 plus shipping (okay, Mom bought that too). I know, I know, a 100k used part is a risk. But you should see my checking account these days! I couldnt wring an OEM part ($280) out of my parents ("Jesda, thats too much car for you. You need a Honda.") but I did get a nice tuition check today.

In fairness to me, I bought the Q when I was making four times as much money.

Will these tools be sufficient? I also have two hammers, some coolant, and a lot of patience.



Thanks!-Jesda

[pito11213]

Is there a pack of patience in that tool kit

Just take your time and be patient. Take pictures during the process to back track.

[Altiman94]

There is no way that those tools will be sufficient. Holey crap man, take that car in. You really have not a clue. Wes, help this man out. Id do it if you were in Iowa, but obviously this is not the case.

[PoorManQ45]

There is no way that those tools will be sufficient. Holey crap man, take that car in. You really have not a clue. Wes, help this man out. Id do it if you were in Iowa, but obviously this is not the case.

Wrong!

Jesda those tools that you have will be fine for the job. At least you have all your tools in one spot. When I replaced my alternator, my tools were scattered troughout the garage.

Also, you don't have to use an OEM alternator. They are a little weak. I think that they put out between 90~110amps@11~15volts. I found that Bosch sells a 190amp alternator for the Q45. It cost me $300. But hey, it's got enough juice to power my stereo.:D. So, I think that it was worth it.

[PoorManQ45]

Be very careful when removing the longer of the two bolts. There is a nut/locking ring on the back of it. When I removed my alternator, I didn't realize that it was there. It was a real pain to fish that thing out of the engine compartment. I guess I should have used my manual

[AZhitman]

^ Very true - Good advice there.

Jesda, you should be OK with those tools. Although that ratchet looks a little wimpy.

[PoorManQ45]

Although that ratchet looks a little wimpy.

Ya, you should get a breaker bar.

[DAEDALUS]

^ Very true - Good advice there.

Jesda, you should be OK with those tools. Although that ratchet looks a little wimpy.

I dunno... I doubt the sockets are any sturdier than the ratchet. If that's one of them real cheap sets I'll bet you bust a socket. My father is the sultan of cheap tools. Not sure how many I broke growing up. According to him, of course, I didn't know what I was doing and I was overtorquing things (even when loosening them, apparently). Only when I got older did I learn that good tools will never break before the fastener. It wasn't me, Dad!

To be fair, I will say that some of the cheap tools out there are pretty darn decent. I don't mind going to harbor freight for cheap, specialty, low-risk tools that I'll only use once or twice.

Jesda please tell me you have more than 1 screwdriver.

[PoorManQ45]

I dunno... I doubt the sockets are any sturdier than the ratchet. If that's one of them real cheap sets I'll bet you bust a socket. My father is the sultan of cheap tools. Not sure how many I broke growing up. According to him, of course, I didn't know what I was doing and I was overtorquing things (even when loosening them, apparently). Only when I got older did I learn that good tools will never break before the fastener. It wasn't me, Dad!

Standard chrome sockets are just fine. I usually get about 90lb-ft of torque from them, before they break. As long as you don't use them with an impact wrench, they will suffice.

Actually, when a ratchet breaks, what is really breaking is the one-way mechanism inside. To prevent this from happening, do like I said, get a breaker bar.

[PoorManQ45]

To be fair, I will say that some of the cheap tools out there are pretty darn decent. I don't mind going to harbor freight for cheap, specialty, low-risk tools that I'll only use once or twice.

Yep. I buy all my tools on sale. I got a set of impact wrenchs for $5. normally $30~$45. They can take up to 350lb-ft of torque.

[ScottJackson]

Those tools may do the job. I've never done the alternator job. I didn't think that set of basics would be enough, but from how it sounds, maybe it is. On the cheap tool subject, I use cheap tools too. I use Craftsman which is cheap, but not overly cheap. For the real low dollar stuff (I have some of that laying around too), I recommend definately wearing gloves while breaking loose the bolts. Ratchets that break inside and make your hand quickly fly into something hard and sharp are no fun.

[AZhitman]

Craftsman doesn't fall into the realm of "cheap tools". I think when we said cheap, we meant poor quality.

Craftsman and Husky are both good quality, inexpensive alternatives.

[Q45tech]

Please provide installed pictures of a 190 AMP BOSCH ALTERNATOR installed on your Q45 and a copy of the bill for $300...........not that I am doubting your WORD BUT lets get real here!

Bosch Remanufacturers does make a 90-100 amp alternator that some national chains mislabel [misrepresent] that fits in the oem space? These fail by the semi load full on a weekly basis.

My searches show water cooled 190 amp alternators [for use on 2004 Audi A8 $1200], and giant air duct cooled models for BMW] and aftermarket rewind 190 amp alternators but their sizes are larger than the Q45 alternator. Most require an external rectifier stack.Ford has some for diesel trucks but they are $800.

High ampere alternators have a disadvantage in that they produce lower amperes at idle speeds than optimized 90-110 ampere units! Why even Lexus only uses a 100 ampere unit.As who wants to run the engine at 3300 rpms [alternator at 7,000 rpm] to get the full rated ouput of the alternator.The oem alternator is less than 7" thick from belt pulley tip to the wiring terminal end. The main problem is that most alternators cannot survive the rpm of the Q 6900 rpm multiplied by pulley ratios yield over 15,000 rpm!

[PoorManQ45]

Please provide installed pictures of a 190 AMP BOSCH ALTERNATOR installed on your Q45 and a copy of the bill for $300...........not that I am doubting your WORD BUT lets get real here!

I'll try to find the bill. IIRC it was a Bosch alternator. I got it from Autozone.

My searches show water cooled 190 amp alternators [for use on 2004 Audi A8 $1200], and giant air duct cooled models for BMW] and aftermarket rewind 190 amp alternators but their sizes are larger than the Q45 alternator. Most require an external rectifier stack.Ford has some for diesel trucks but they are $800.

Hehehehe. The reason that those alternators that you are refering to require extra cooling is because they are inefficient. Meaning they generate too much heat for what they do.

As who wants to run the engine at 3300 rpms [alternator at 7,000 rpm] to get the full rated ouput of the alternator.

the Q45 just starts to pull hard at ~3000rpms. So, that's where it usually runs for me.

The oem alternator is less than 7" thick from belt pulley tip to the wiring terminal end. The main problem is that most alternators cannot survive the rpm of the Q 6900 rpm multiplied by pulley ratios yield over 15,000 rpm!

Nope, it came with a larger pulley. I think it maxes out at ~10000rpms.

High ampere alternators have a disadvantage in that they produce lower amperes at idle speeds than optimized 90-110 ampere units! Why even Lexus only uses a 100 ampere unit.

Standard alternators put out ~50amps at idle. I think that they reach peak output at ~2500rpms.

At idle, mine puts out ~75amps. It maxes out at 4500rpms. That doesn't seem like too much of a disadvantage to me.