Alternator Failure?

[Christien]

Here's the situation: last night I was driving home on the highway, and the car starts bucking a tiny bit. No problem, I thought, pretty windy out. Then I noticed the headlights look dim. Long story short, I pull off to check things out and in the off-ramp the engine dies. I manage to coast to a parking spot in a rest station (what luck!). I tried to restart the car, nothing, won't even turn over. I'm getting some dash lights, etc. but no start. End up flat-bedding her home.

Today I put a charger on the battery and after 5 or 10 minutes I was able to start it long enough to pull it into the garage. My thought is that the alternator is shot. I've searched these boards and read the Haynes about testing the alternator by jumpering it with a screwdriver, but haven't been able to keep it running long enough to perform this test. I've had a charger on the battery for an hour or so now, and I'll try it again tomorrow, but in the meantime, does anyone have any thoughts other than alternator failure?

Thanks,
Chris

[Eldorado]

sounds like alternator or battery to me.

unfortunately if your alternator is borked, your battery could be/will be soon to follow.

[Christien]

Lovely. I guess when it rains it pours, eh? (or blizzards as it did in our area today )

At least the alternator's easier to access and replace than in the 911!

[Eldorado]

true on both accounts

ehhh hamilton!!! there's a good half-dozen or so people i can think of in our area.. i'd like to see some sort of meet this summer... hopefully we can pull something off!

take the alternator to a shop and have it tested. most places will do it for free for you.
best case scenario is that it's your battery that wont hold a charge anymore... any idea how old it is?

[Christien]

No, no idea, although it looks fairly new. I'll ask the PO. Is it a real pain to get the belt off and back on to have the alternator tested?

Check the PP Canada board - there's a bunch of us 911 guys trying to put together a fun run date in May sometime. It'd be nice to have some other types along. Are you in Hamilton as well?

Thanks for the tips!
Chris

[Eldorado]

i'm in mississauga actually, not too far from the hammer...
i dunno.. to be the lone 944 on a 911 run....

[Christien]

Ehh, we just have to get a couple more marques out. Would be nice to see a couple 928s and 914s as well. I know there's at least 1 or 2 928s around my area. No idea if they're to found hanging around these boards, though.

[Brando]

It's not difficult to remove the alternator on these cars. Just remove the airbox and AFM, loosen the Alternator/Air Conditioner belt and undo the 2 bolts that hold it on.

To loosen the belt, use the turnbuckle that's on the bottom, near the A/C compressor. It works for tensioning both.

[Christien]

Ok, here's a bit of an update. Even more puzzling...

I wanted to do the screwdriver test on the alternator, but I could't keep the car running long enough to test it. Even after charging the battery all night, it would only run for maybe 2 or 3 seconds, then die. So I thought maybe the battery's shot. So I took the battery out of the 911 (which I know is fine) and swapped it into the 944 - same thing. Plenty of juice to start the car, but it only ran for a few seconds. Both batteries are reading ~12V on the voltmeter (11.45 for the 944 battery, 12.something for the 911 battery).

Now I'm thinking, what are the chances it's just out of gas, or maybe a fuel pump problem? The fuel guage reads just under half, and jumps up there when the electricals are turned on (ie needle's not stuck) but it could be broken. But that still wouldn't explain why when I was driving home Monday night the headlights got really dim and the heater fan grew weak.

The battery should be able to produce enough juice to at least power the spark plugs for at least a couple of minutes, no? all the other electrical stuff (lights, fans, stereo) were of course off, except the tiny interior light.

Any ideas what's going on here?

Thanks,
Chris

[Eldorado]

can you keep the car alive with your foot on the gas out of gear?

[Christien]

Nope.

[Eldorado]

how are your battery connections looking? any corrosion?

[Christien]

No, they're pretty clean. The 944 connections are a bit dirty, the 911 connections perfectly clean. Both batteries are relatively new (maybe 1-3 years old). I also tried using a jump-starter - same thing, and I know the charge is full in that because it's got a meter.

[Eldorado]

well it still kinda sounds like an alternator, but you're right... it should run for a lot longer than 2 or 3 seconds on a good batt...

how do the grounds on the back of your engine look?
what happens when you first start the car and give it LOTS of gas? does it still bog out and die?

[Christien]

Good question - I'll try that and see what happens. As for the grounds on the back of the engine, I'm assuming you mean where the negative cable from the battery attaches to the engine chassis? I don't know how clean that is - I'll check, try the gas thing and report back in a few minutes.

Thanks for your help with this!

[Eldorado]

there should be a big honkin' ground wire attached to your firewall behind your engine.... check that while you're at it.

[Christien]

Checked the ground wire, looks fine, firmly attached, not overly dirty.

I tried to start it with the gas pedal floored - it would only turn over once, wouldn't start, just one "chug". So I hooked up the jumpstarter, same thing. Took that off, put the charger on the battery for 5 or 10 minutes, same thing, one chug. The thing is, the voltmeter is still reading 11.45 on the battery!!!

[Christien]

Another small update: the PO says the battery is new, although it has been drained to dead at least twice now.

[Razorback1980]

Have you checked the positive cable going from the battery to the starter? The connection at the starter is very important, make sure it is clean and tight. Put a voltmeter on the battery and take a reading then take a reading on the starter solenoid and see how close the two voltages are...should be close or look to the positive battery cable. Take the connection loose and make sure there is no corrosion on there and the reattach using some sort of anti corrosive coating. It could still be a ground...take them loose and clean under them and don't just make sure they are tight. Use anticorrosive coatings on each location.

Hope this works...

[Christien]

I really doubt it's the connections, as the car has started fine several times over the last few months. It's never had a problem firing up until Monday night with the power loss, and it was the power loss that came first, rather than the no-start issue.