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YOUR RESEARCHAlternator Questions
Reported repair
Replace starter
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1
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0
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Reported fix
The problem went away after I changed the starter.
Leading evidence: 'Replace starter' (1 discussions report resolution; 0 report an unsuccessful attempt). Across 1 matching discussions, the most frequently mentioned possible cause is 'started failing' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Replace starter' (1 discussions). For that action, 1 discussions report a resolution and 0 report an unsuccessful attempt. The most frequently reported fix is 'Replace starter', supported by resolution reports in 1 discussions. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
In all fairness, I feel much better knowing I replaced the starter and Y-cable, however.
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Performed · outcome unconfirmed · Original poster
I also have replaced the Y-cable and the new pig-tail.
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Performed · outcome unconfirmed
The "Old School Conventional Current Flow " theory ( that is still widly used ) that says current flows from Positive to Negative can be misleading at times...
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Suggestion
Take your own voltmeter and while the engine is running, check the voltage reading you get measured at the jump point and ground in the engine bay, then, while it is till running, check the voltage at the battery and report back.
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41 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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2 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
When my 2004 C4S suffered from slow/no-crank-when-hot, the only change I made was a new Y cable and it fixed everything.
So - The Car - 1999 (Early 3/98 Build) Carrera Coupe 6 Speed. 130k miles
I noticed I was having a hot-start issue about a week ago, as well as low voltage reading. The battery is fairly new 2024 purchased. I read online about replacing the Y-cable, and got to work. I also decided to replace the Alternator while I was in there (I think it's original...). The Y-cable actually looked fine, but smaller in gauge compared to the new one for sure. The big thing I noticed however - was this pig-tail connector to the alternator. It definitely looks a bit tattered and maybe melted a bit? Can I just replace this with a new pigtail (
This one? Link
This one? Link
) and pop on a new alternator and Y-cable and be set? Or is this faulty pig tail an indicator of something else.
Thanks!
I don't think it's a starter. Multimeter showed that thing is still in good shape. I'm going to bench test the alternator out of curiosity too - but the original Y-cable did look way smaller in diameter/gauge than this new one, and the bad pigtail I think all translated to bad hot starting. It wasn't slow hot starting, it was just weaker. At least I'm hopeful it's not the starter!
Its getting heat soaked and drawing a ton of power. Thats why its hitting the elecrical system hard. Happens all the time in tge 996. Maybe im wrong but its what happens in this car and most owners chase their tail between the battery and alt for a while and then swap the starter. I guess we will know in a few days as u get through your diag.
When my 2004 C4S suffered from slow/no-crank-when-hot, the only change I made was a new Y cable and it fixed everything. Alternator was fine and is still original at 110k miles now.
I think he was talking about the starter. The Y cable is a known issue and it's a failure point because the design has two wires connected to each other that aren't well protected from the elements, so they eventually corrode, the corrosion limits the flow of current, which lowers the voltage so that eventually the battery isn't getting charged and people mistake that for a failing alternator or battery or both when in many cases it is neither. It's the Y cable and here is what it looks like when it starts causing issues:
The heat generated by the current trying to flow through it to charge the battery and keep the fans going eventually caused the covering to melt.
I'm with DeJeeper on the starter. With age, all the windings expand more when hot, creating mechanical interference that requires more power to turn. When cold, the windings are back to normal size and the starter turns fine. Electrically, the starer will measure fine. Here is a graph of the voltage drop seen on mine with the hot start problem, taken with a Durametric. The problem went away after I changed the starter. Same thing happened on my Cayenne. The Y cable is an issue but corrodes based on the environment that the car is in. These cars are old, If it's been in a dry environment for it's life, it might be OK. If it's been in humidity for it's life, and shows corrosion, I would change it. Sometime the corrosion hides under the joint tape.
Just got the alternator tested - it's A-OK. I think I will still replace it with the new unit (I already bought it...), and it'll be a peace of mind thing. I also have replaced the Y-cable and the new pig-tail. Now is the question - Since i have everything already out - should I just replace the starter too? It's not THAT expensive, but it is a bit of cash. I'd hate to get it all back together and still have the same issue...
I think I know the answer to my question, unfortunately.
FWIW, I personally wouldn't replace a working alternator if you can return the one you purchased. The original one in the car is a genuine porsche part that could have many more miles on it. New alternators, esp. if not geniune porsche, have unknown quality. I've got 110k on mine and it's still going strong.
For the starter, I totally agree with the comment about getting a starter from amazon. I bought and installed
this one
this one
5yrs ago and it's working great.
Thanks for the starter link - that's for sure what I'm going to buy. The alternator is curious. I'm kinda torn - I understand your reasoning - and it is generally easy to replace. I can't return the alternator I got, unfortunately. Maybe I just keep it as a backup spare and put in the new one? I'm not sure what to do.
Backup spare is a good idea. You might also be able to ebay it and recoup some $$'s but if you have the space to keep it, and don't need the cash, then storing it seems reasonable.
One picture shows the access to the starter after removing the plenum. The upper bolt and wire nuts are easily accessible. The second picture shows where I inserted the multi-extension socket under the alternator to loosen the lower bolt. Good luck!
Got it all replaced this weekend! Really pretty easy job - not difficult at all. I ended up getting a Bosch starter. While I was in there I found two rotted vacuum hoses too. My idle and start-up overall is way better and faster. The long extension is the trick for sure!
Still reading a low volt reading, however. I've charged the battery, but maybe it's dead or dying?
If you replaced the Y cable and the alternator and are still getting a low voltage reading, then the only thing left is the battery. If, before all the work, you were seeing low voltage, then the battery was not being properly charged anyway and that may have sealed its fate.
Check your engine ground...It s on the passenger side bank 2 head and bolts to the body behind the right rear tire...
These are also a common cause for charging/starting issues and various other things ..(can cause oil pressure gauge issues for instance)
Most people often forget about the ground side of the system, but without the ground nothing works correctly..
: "The Electrons " actually flow from the negative battery terminal through the Negative side of a circuit first, then to the Positive side....
The "Old School Conventional Current Flow " theory ( that is still widly used ) that says current flows from Positive to Negative can be misleading at times...
Adding another 4 Gauge Ground cable from the Alternator bolt to the engine mount bolt can have an improvement on the Charging/Starting also ...
Thanks for all the help. I think I just assumed the battery was good as it has a 2024 date on it, but you're probably right - it was a slow death and there's no saving it.
I have checked that engine ground (Had to remove it to re-install my mufflers), but I'll give it another once over, as it's relatively easy to get to.
True, true.
In all fairness, I feel much better knowing I replaced the starter and Y-cable, however. Like I said, it got me to fix an unknown vacuum leak as well. Working on this car is actually quite enjoyable, and I enjoy learning about it and gaining more and more experience.
Yep, I had a good friend who was thinking of selling his 996 due a very serious surgery he was on a waiting list for....I convinced him to keep it for Recovery Therapy ....lol .... He did, and it was great Therapy to help him recover that took two years....
Electrical engineer here. A loose/unstable ground connection would not cause a consistent low voltage. It would cause an inconsistent low voltage and that rise and fall of voltage could wreak havoc in electronic sensors. I should have mentioned this earlier, but it is always a good idea to put dielectric grease on all major electrical connections. It is cheap and keeps contacts from corroding.
As for Therapy, I also agree with Porschetech3, that they are great therapy. Because I have caretaker responsibilities, five years ago, I swapped in working on a 996 for playing golf (which I am very good at) so I don't have to go any further from home than the garage. Been a real blessing I hadn't expected. Also helps that there is a track here.
Not sure if has been asked or not. What r u basing the low voltage off of? The dash on these cars usually show around 13v which looks low based on most modern cars but is normal.for the 996. What is the voltsge when check with a multimeter at the + lug in the engine bay and at the battery?
That is a dead battery. You need a new one.
With a new alternator, battery and Y cable you should read 14v on the meter in the car. Mine does. I got some bad advice from a local "expert" and replaced everything. The bad news is I wasted $600. The good news is I got 14V unless all the fans turn in and then it drops a little.
Alright - New battery - Still low voltage reading at the dashboard.
What did I miss? Is it just a bad gauge? No starting issues what so ever and everything runs great.
That is odd. Now we have to diagnose and see why the voltage is still low. Take your own voltmeter and while the engine is running, check the voltage reading you get measured at the jump point and ground in the engine bay, then, while it is till running, check the voltage at the battery and report back.
This is what my voltage meter says on the dashboard, following a refresh of battery, alternator and Y cable. Engine at temperature and fans running. No fans it goes to just over 14v.
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