sm

EDIT -
Well, I made my longest road trip in my car this weekend from NYC to Boston, and was stranded someone in CT on the way home. Luckily my friends who were following me in their car was there to drive me home. I have to drive back up to CT to fix the car and drive it home from the parking lot it's at right now.

The voltmeter dropped all the way to the bottom and the car soon loss all power. I was able to coast to the side of the road and have my friends jump start my car so I could drive it to the lot.
On the way to the lot, the car died again, after the battery lost all it's charge. I believe it's the alternator/voltage regulator that's bad judging from the behavior of the voltmeter these past couple of weeks.

Would anyone know what the part number for the voltage regulator is? I'm going to replace that first, but I think I may bring a spare alternator with me too since it's 130 miles from home. I don't want to have to make another trip up there.

Also, can the diodes - as mentioned in this thread's replies - be replaced? Where would I find them?

So what's tools would I need to replace the alternator? I know a screwdriver is needed for the voltage regulator. Anything else?

And how do you check for correct tensioning of the belt?

Thanks everyone for the help.

sm

Guys:

I was getting psyched up by all of the positive replies to my <a href="http://forums.rennlist.com/scripts/rennforums/ultimatebb.cgi?ubb=get_topic&f=15&t=004215" target="_blank">Road Trip Post</a> and ready to do a road trip. Now this happens.

I was driving in traffic going about 10 MPH when I noticed the red[!] dummy light was dimly lit and the voltmeter was below the 12 volt hashmark. The voltmeter's own warning light was on as well, though barely. While continuing to drive in slow traffic, varying between 10 to 20 MPH, the voltmeter would occasionally jump up to 14 volts and then go back below 12 volts. This cycle happened a few times until I got home around 15 mins later and shut off the car. The car did not stall at anytime while I was driving.

I want to mention that when things were "normal", the voltmeter would drop when I stepped on the brake pedal and bounce back up when I released the pedal.

So has anyone had any of these symptoms prior to a breakdown of the alternator or battery? Should I just try to clean all of the connections by the battery posts?

Please help. IceShark, you seem to have boku knowledge on electrics, so any advice would be appreciated.

Thanks in advance.

sm

Devildog2067

Min'es been doing thatt for a year and a half; I think the alternator is on the way out but its not gone yet.

IceShark

I would first go after the alternator, especially the regulator. Check the alternator belt, too, to see that it is tight.

The brake light deal also points towards the alternator as they don't normally draw enough power to knock down your system voltage.

Your battery may not be the best but even if it is crummy you shouldn't see these wide fluctuations coming out of the blue for no apparent reason once the alternator is running.

sm

Thanks for the replies.

When the alternator goes bad, what actually quits? Is it the regulator? The other internals? How long should they last if the cooling duct and other parts are properly installed?

Thanks again.
sm

Mark Lue

[quote]Originally posted by sm:
<strong>Thanks for the replies.

When the alternator goes bad, what actually quits? Is it the regulator? The other internals? How long should they last if the cooling duct and other parts are properly installed?

Thanks again.
sm</strong><hr></blockquote>

Make sure the alternator belt tension is correct !

The shop I bought my Voltage regulator (under $20 US) says the original shaft and bushings are very good and can last a long time but the brushes can wear unevenly. Try replacing the voltage regulator first you can find a replacement at most places that rebuild alts, it is a common Bosch regulator. The regulator can be removed from the alt by removing 2 screws but installation requires you to insert the new one at an angle and apply pressure while trying to get the first screw started.

Here is something I found in another post that I am meaning to try when I get the chance. It may not apply to your problem but then again.

"Before you tear apart your alternator, like I almost did, see if the voltage is being displayed correctly by your voltmeter on the instrument cluster. That was the problem with mine. Remove your instrument cluster and you will find a resistor attached to the back of your voltmeter. This easily slides out of its connections if you wiggle it slowly. The culprit is corrosion in the contacts. Use light sand paper on the resistor and a little in-and-out friction using the resistor in order to clean the contacts in the voltmeter. Don't think that you can go to Radio Shack to find a new resistor: I already tried and they don't carry it. I was a little upset until I found that the resistor was still good and it was just corrosion. Try this, it works!"

IceShark

When our alts go it is usually the regulator, followed by the diodes which are inside the case which you can also replace.

As noted our alts are pretty sturdy and the bearings and shaft should last an awful long time. You can have internal connections come lose or cook the laquer finish off the windings but this doesn't happen often.

The heat will kill the alternator pretty quick. Also if your alternator has to really work hard, like you have a bad battery or huge stereo amp load on it, you will kill off the diodes quicker. An alternator that is run close to its maximum rating can eat diodes like crazy.

Mark Hubley

For years I have occasionally watched my voltmeter drop below twelve, then later on pop back up to normal. However, it seems a little different from your condition in that no other lights come on. Anyway, I have pulled over when the meter reads low and tested the voltage across my battery with a tester and found 14 volts. So, I recommend that you actually test the voltage across the battery before replacing an alternator.

sm

Bump for Edit...

IceShark

The OE Bosch part number for the regulator is #1192052015. It is the same for every 944/951 I have checked, even the old 90 amp alternator. I'm actually ordering a slug of adjustable regulators that would fit yours tomorrow, but that isn't going to help you much if you want to do this quick. Can't help tonight on the diodes.

You are going to need a bunch of tools including jack stands. You need to remove all the air intake plumbing just to get at the damn alternator on a 951, plus the belly pans; it is a real pain in the ***.

This is going to be a problem with it sitting in a parking lot 130 miles from home base. You could just take it to a garage and fork over the money to have them fix ... which will probably entail you spending a night there. Or send a garage the keys and tell them to tow it and fix. Another idea is to bring along a fresh battery, maybe two to be safe, put it in and drive the car home. And keep all electrical items off all the way home! I have done this before. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

If you decide to do the latter and have some time I can order you the adjustable regulator and get it to you in a week or so. Cost is $16.50 plus 4.50 shipping for about 2 day delivery.

Good luck, the battery idea might be your cheapest bet since you may have hurt the current battery you have in there due to unusual charge/drain cycles.

sm

thanks Ice:

so how far were you able to drive on the battery?

IceShark

It was a '63 Chevy BelAir! <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" /> I could drive it for a week since about all that was drawing juice was the coil. Voltage is your problem .... once you drop below something like 8.5 or 9 volts almost everything stops working.

If you have a fresh fully charged battery I think you should have no problem getting it home. As a cushion you might want to check to see if you can pull the fuse that supplies the heater fan, which is always on low speed when the ignition switch is on, without disabling the DME. I don't have a wiring diagram handy, but keep this in mind. The fan on slow speed probably won't kill you for a 130 mile trip anyway. And don't lay on the brake while at stop signs. Those bulbs draw a fair amount of current. I think you should be OK especially if you have a buddy in another car.

If worse comes to worst you can just pull into a garage and have them recharge your batteries, they will probably do it for free if you get some gasoline.

Hans

[quote] SM: so how far were you able to drive on the battery?

IceShark:
The fan on slow speed probably ....
And don't lay on the brake while at stop signs. Those bulbs draw a fair amount of current.
<hr></blockquote>
Both above are highly recommended.

Also: use cables to start your car,utilising the buddy's system to supply the high energy required for turning the starter motor.
Dont use the fresh charged battery for this, even a jump start will be better.
130 mls must be possible with an 63 AH fully charged battery.
Go for a re-charge as per the Shark's recipe when you get below 10 Volt.

PS: I have seen (Bosch) alternators with heavy mechanical damage inside, ground strip snapped off & killed the wires (mine some years back).
So it does not have to be the regulator although it would be my first thought.

IceShark:
What about disconnecting the wiring to the alternator for the trip?
I would asume that the voltage regulator is dead, this might result in undesirable current flow over the alternator, also the alternator might want to try and charge the battery with AC, consuming a lot of the energy required for the trip home.

TakeCare

sm

Can the voltage regulators on the 951 be replaced from the bottom of the car? I have ramps in the trunk which I JUST bought prior to the car breaking down. It would be a whole lot easier then draining coolant and such via the top of the engine.

Thanks for all the quick help. I'm gathering the tools and courage to make the trip out there...today or tomorrow.

sm

sm

Iceshark, what's your email? I tried emailing to
wraydan@msn.com, but it didn't go through.

Bob S. 1984 Silver

Also note:

If the battery is marginal, the load on the alternator is constant as the alternator tries continuously to charge the battery. This will, over time, burn out the regulator and most likely the diodes. Take the battery to an auto store and have it tested. I have found a number of failures over the years that could be traced to a battery problem.

BTW...diodes usually fail in the "open" mode. But, some can short. This places additional stress on the electrical system. Check all ground wires as well. Resistance can play havoc with auto electrical systems.

Good luck

Bob S.