17 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHVoltage drop after regulator swap
Leading reported evidence
Install bosch starter and it has been good
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Installed a new Bosch starter and it has been good for many years.
Leading evidence: 'Install bosch starter and it has been good' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check cable and report back, probably brushes need indeed' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
indeed a new alternator is better than an old one, but ours, is a serviceable part, used heavily by many cars in tha VAG group.
Check cable and report back, probably brushes need indeed
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
I will check the cable and report back, probably brushes need indeed to settle.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
I usually clean the rotor/slip rings with very fine crocus cloth and brake clean/compressed air till its nice and shiny again and the little spaces between the slip ring pads is clean.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
I usually clean the rotor/slip rings with very fine crocus cloth and brake clean/compressed air till its nice and shiny again and the little spaces between the slip ring pads is clean.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
My mechanic said that probably the copper side of the alternator (where the teeth/legs touch) may need some cleaning with sandpaper as well, due to the shape that has taken all these years.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
17 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
1 acknowledgements have no verified action link; they do not establish a repair result.
Hello, I recently upgraded my regulator with a new Bosch one (made in China). The car is steady at 14v more or less but if I have AC on, when the fan in front kicks in, I have a 2v drop as seen here:
After 2-3 seconds it climbs back at around 14v.
If I have the heating window on as well as high beam lights, volts are at 13.8v, the drop goes down to 11.9v and then it stabilises at 13.2v...
Faulty regulator out of the box? With my previous regulator I was at 13.2 all range...
What was wrong with the OEM regulator?
Sometimes the voltage increases or drops depending on the battery�s charge level. It�s not like the old school regulators where the target voltage is always 14-14.4v. That level of voltage, over time, weakens the battery. It�s better to put higher voltage of 14-ish and then back off once the battery is charged to 13-ish, which is what the OEM regulator does well.
In either case, old or new, what you are seeing is probably normal (not an issue).
It was 22years old. the teeth/legs were down and it would pop an alternator problem on the dashboard. the car would be steady at a slow charging at 13.2v. with the new regulator, it went up to 14.10v.
My mechanic said that probably the copper side of the alternator (where the teeth/legs touch) may need some cleaning with sandpaper as well, due to the shape that has taken all these years.
If I had my 25 year old alternator out, I wouldn't replace any part of it. I would buy a new Bosch alternator, install it and move on. I made a mistake a long time ago by installing a rebuilt starter. It busted in less than a year. Installed a new Bosch starter and it has been good for many years. Live and learn...
Yea i probably would have replace the entire alt too but a new regulator can work well if the bearings and stator r still good.
U will always get a voltage drop when high amprage items kick on and the system does recover. I would drive the car for a few hundred miles and let the brushes wear into the stator. They probably r not making full contact yet.
Your symptoms are consistent with a corroded Y cable, the one that delivers current from the alternator to the starter and from there to the battery. Part number is 996-607-019-xx. The wire from the alternator is swedged to the wire that goes eventually to the battery. This connection is not weatherproofed and over time, it corrodes, creating resistance to the flow of current. As more things turn on, e.g, fans and lights, the more current is drawn, there is voltage drawn to the corrosion hence you see 11.9V at the battery. The other 2 volts are in the corroded cable.
If you can pull out the alternator, you should be able to the see the wire. It looks like this when it is bad. It is the end connected to the starter.
all great answers, thanks. indeed a new alternator is better than an old one, but ours, is a serviceable part, used heavily by many cars in tha VAG group. Hence my decision to change the regulator. I will check the cable and report back, probably brushes need indeed to settle.
is it an engine out to replace the y-cable?
Negative. It can be done without even lowering it. I've been told that if you snake the cable in from the side where it mounts to the +Jump point to the right of the power steering pump, it is easier than if you connect the alternator and starter and feed to from there out to the jump point.
hello I got the car last Friday from my mechanic coming back from summer holidays. He swapped the y-cable with the new upgraded part, but still the same behavior: if the car is idling and the A/C is on and the fans kick in, the voltage drops to around 12v and recovers back to 14v. if the car is not stationary, this voltage drop is not happening. Or if the car is idling and a/c is off...
Should I go for a new battery?
Your battery won't change the voltage you are seeing as a function of RPM. The only thing that will do that is the alternator. You replaced the Y cable and the regulator. All that is left is the alternator.
Well, doesn't seem like a major problem at all, as long as voltage recovers in a couple seconds.
2 things come to mind, either the voltage regulator is a inferior cheap china design/clone, even though it says Bosch, and is slow to react. Or the rotor/slip rings of the alternator where the brushes ride is dirty not letting the brushes make great contact for quick response to voltage drops.
I usually clean the rotor/slip rings with very fine crocus cloth and brake clean/compressed air till its nice and shiny again and the little spaces between the slip ring pads is clean. this will let the new brushes seat well and quickly. Lots of time brush material that has worn off past brushes and needs to be cleaned out or it will take a long time for the brushes to seat if ever...
jmo
thank you for all the replies. I was thinking that somehow my battery is near death and does not support the alternator when trying to compensate for the extra amps. Anyway, I will live with it, cant start swapping parts. My Z3's battery is dead, so I will buy a new for the 996 and transfer this one to the Z3. If it makes any difference, I will report back.
This is a source reference. Confirm exact model applicability in the original material.
