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Discussion Starter · #1 ·
Good day Guys,

Battey light came on 67k 3.2 mk2 quattro (girlfriend's) and I suspect the voltage regulator( 12.1v when running). Any tips for getting to the earth nut, 12v live bolt and the screws?

My guess is that the inlet manifold has to come off to get in there or to remove the alternator? No access from below as the oil cooler in the way, from top squeezing through between the dipstick, hydraulic hose, radiator and inlet manifold is not working for me. Arms too big.
 

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I believe that access is gained from below by removing the engine under-tray and part of the wheel arch liner in the RH wheel well and then unbolting the AC compressor and shoving it out of the way.
Obviously do not release any of the refrigerant hoses.
 

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Discussion Starter · #4 ·
Had the voltage regulator replaced by a local authorised garage. The light goes off when you rev it to 3000rpm, but the battery voltage is only 11.8v and dropping. Its not charging. The guy said the new brushes needs to run in to make better contact. I say it sounds like a tale.

See what my alternator looks like now! One of the ribs are broken!

 

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Discussion Starter · #6 ·
No but it didnt show poor earth symptoms. Cleaned the two below the fuse box and the other end on gearbox below air box. No change.

Bosch dealer.

New brushes are square, i thought the current would be limited by poor contact, but not voltage.
 

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HMP73 said:
The guy said the new brushes needs to run in to make better contact. I say it sounds like a tale.
Sounds like a total load of B0110cks to me as the brushes fitted to all of the alternators I have worked on (Did a lot around 20 years back) were square faced and ran against a flat slip ring.

HMP73 said:
The light goes off when you rev it to 3000rpm, but the battery voltage is only 11.8v and dropping. Its not charging.
Most alternator systems are or were designed to produce maximum output charge at between 1500 and 2000 rpm, the ignition light should extinguish at around 1000 rpm. The alternator regulator should limit the output of the regulator to a maximum of 14.4v.

The problem could be bad earthing/contacts or a faulty alternator.
 

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YoungOldUn said:
HMP73 said:
The guy said the new brushes needs to run in to make better contact. I say it sounds like a tale.
Sounds like a total load of B0110cks to me as the brushes fitted to all of the alternators I have worked on (Did a lot around 20 years back) were square faced and ran against a flat slip ring.
Yes, the repairer's remarks have that distinct aroma of male bovine droppings.

YoungOldUn said:
The problem could be bad earthing/contacts or a faulty alternator.
The problem could also be that the internal work was carried out with the same care and skill that's clearly been devoted to the outside of the alternator.
 

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If they have fitted a new regulator with brushes to a knackered worn slip ring it will take time for them to bed in properly as the new brushes will be flat, but I wouldn't have thought it would cause issues.

The problem is they have replaced the voltage regulator when the problem might be worn sliprings
 

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Discussion Starter · #15 ·
Yes in the last picture the old set of brushes are fitted. There is a cover over them, the one pictured with the white sticker/part number.

No you cant fit your arms in between the radiator and inlet manifold to unbolt it. The alternator have to be removed and turned to get access from the top.

Honestly I dont know if its worth doing. Next time i will just replace the alternator. One way pulley and all. Seems like these are not even being refurbished. Hence its on my garage floor. I still dont know whats wrong with it, and dont have the equipment to do an insulation breakdown test, or a circuit diagram for the stator and what must be the rectifier diodes.

Im sure access was gained by removing the a/c to the side as suggested earlier in the thread.
 

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In the old days when I replaced brushes, I had to take the alternator completely apart. The fact that they now seem to be bolt on is good new to me. Taking the alternator out on a 2l engine shouldn't be too hard. Not that it's necessary right now, but it's good to know just in case.
 

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Discussion Starter · #18 ·
Took it for a test drive.... Looks ok. Battery light stays on during cold starting only until you blip the throttle to 1800rpm, it then charges fine after that. :?:

 

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YoungOldUn said:
The brushes on Bosch alternators have always been in a separate module fitted from the outside.
The TT is my first German car. I use to drive old-French (brushes inside the alternator) and Japanese (no need to replace brushes, ever)

@ HMP73: I hope as they run in, charging is OK at idle too. Or is the tension of the serpentine too low?
 

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Discussion Starter · #20 ·
Well its not the brushes that went wrong, sure they are worn but have allot left as you can see in the pics.

Its either the regulator in the brush assembly, or on the alternator-the rectifier diodes, or the sliprings, or windings...
 
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