ClutchBiteNom

Recently, I've purchased an '84 928 that...well.. it was running and it was working. Quite well, actually. About 2 weeks in, I had parked the car one night, and when I tried to move it, the car would just not start. The electricity would start, and then dim a bit, and then after a few times, the electricity would completely not start at all. Tried jumping it, tried roll starting it. Complete, silent death. Nothing worked.

I had it towed to a shop, in which they charged me $650 to replace the alternator that they said was fried. By the time they had replaced the alternator, I had already left Denver and flown back to LA. (I live in LA, bought the car in Denver)

Here's where it get's interesting:

I'm communicating with the mechanic via phone, they said it works now, and shouldn't need to worry about the alternator for a while. I paid via card. I allow them to drive it back to my friend's appt, and I arrange for transport from Denver here to LA.

Last night, they drive the car off of the transport vehicle, and drive it down to me, and I joke and say "haha last time I saw this car it wasn't working!". I sign the papers, pay the transport guy, and go sit in my idling 928 that I've missed so much and am understandably excited to drive home. 30 seconds later, you can hear fluctuations in motor, it sounds like it's struggling, and it just... turns off. I didn't even touch a thing yet. I couldn't believe it. Right when I get it. I tried re-starting it, exact same situation. The electricity worked but not the engine, then the next try, my lovely car became just a lovely paper weight.

As you can imagine, I was very, very unhappy. Called for tow, waited an hour. And rolled it with my friends like it was a toy car into my parking garage. HOORAY! Best part is, the windows are down!

So. Is something frying my alternator? Or was it just...really not replaced at all.. just... patched up temporarily?! I can't express my sadness!

Alan

What causes your no start sounds more like a dead battery, the alternator not working correctly could lead to a dead battery (and that may have been their diagnosis) - but the alternator plays no part in starting the car.

You need to charge the battery - and if it has been abused much by not being charged over an extended period due to a failing alternator (or even if was just left discharged for long) - it will be toast anyway - time to take the battery out and to a shop for a battery test and most a likely a replacement. Have them test it on a real load tester (this is not a handheld unit - its big).

Then with a good battery able to start the car - you need to test the voltage at the jump post (in the engine compartment) while running and report the voltage: at cold ide, at hot idle and at ~3000RPM.

Alan

ClutchBiteNom

Thanks Alan! I'm clearly..still learning about what everything in the car does! That's why I'm here, I guess. Well I hope what you've said is indeed accurate, because that would be significantly cheaper and more simple, it seems.

hacker-pschorr

IMO you were not "scammed" unless they charged you for an alternator and never put a new one on.

If it wasn't bad, then it's an incorrect diagnoses. That's something you have to get used to when relying on a 3rd party to diagnose and work on your 928.

I agree with Alan, get a solid battery source and go from there.

I had a reoccurring, random starting issue with my 81. It turned out to be the 10 gauge (or so) wire that goes from the power block on the passenger side under the hood to the starter. The wire was corroded inside the seething. Externally the wire looked fine, stripped it back to find only a few strands still connected.

dr bob

The alternator is pretty clearly visible from the top left front (driver's side on US cars...) of the engine, looking down to where the lowest belt drive connects. Shiny clean new or remanufactured alternators are... shiny clean. You should be able to easily see if the one you have meets that criteria.

Alan is the guru of electrical things 928. You'll need an electrical multimeter and, perhaps more important, the ability to use it and report readings you get. Some of the phrasing you used, like "the electricity would start, then dim a bit..." may be a language/translation issue. If it isn't be sure to let us know so the directions are more appropriate for you. Electrical issues in the 928 are a mystery to many, and it's very easy to spend $$$ on a shop that troubleshoots problems by just replacing parts until the problem goes away. I don't live in the LA area anymore, so no easy opportunity to use your car for an electrical troubleshooting example in a clinic.

The Patman

I've seen this exact thing at the battery cable itself (corrosion under the covering, or even under the cable clamp, or under the terminal to post connection). It keeps the battery from taking a full charge even if the alternator is working fine, and it also prevents it from delivering full current on a start as well.
Once in a while, a flaky connection under the battery terminal will even prevent the battery from charging with an external charger clipped on, because most folks just clamp on to the entire battery cable terminal, and not directly to the battery post. Such that the bad connection is still between the charger and the battery post an inch away.
On occasion, there may be a very small patch of "good connection" on a battery post, but during the start, all the current tries to flow through that tiny "good spot" and arcs and burns instead (like a welder, but ya cant see it). Thus making a bad connection even worse, cause now the tiny good spot is burnt!
Then the next time you turn the key (moments later) there is nothing at all.

jcb928

$650 seems high,

Rebuilt Bosch Alternator is $90

How many hours does it take? 2?

Mrmerlin

replace the ground strap cable in the battery box.
Spray the CE panel with deoxit spray,
and also the 14 pin connector under the hood

SteveG

Second to the comments about clean circuits and check continuity of the batt ground in the hatch, they can corrode under the sheath: look fine, but not carry all the electrons. These cars can be tough on batteries. Sometimes it will turn over, but not start b/c the voltage is weak. You may have a battery drain. Most do, so it can't sit w/o a batt maintainer. Most of us have a Schumacher or a batt cut off.

Welcome.

jeff spahn

Get a new battery after you check the ground and main cables. Then get a battery tender junior and keep it plugged in if you aren't driving it.

The Patman

Haven't heard from ya in a few days, didja get this one fixed?

the flyin' scotsman

$650 seems extreme......just had a alternator rebuilt for $73 including a new pulley and woodruff key.

A new battery seems at least a reasonable starting point to getting the car back running then diagnose from there.

harborman

That ground strap from battery to body can be bad even if it looks good. I had to replace mine. The connection was bad inside the end which goes to the body. You can buy a replacement for about $40 all made up like stock.

dr bob

Roger has a 2ga tinned replacement, with shrink sleeve, that's a perfect fit.

LEADASS

My ground strap looked as new at both ends. When I cut the plastic... lots of green grungies. Replaced it a I owned a new car!!!