ok, so after man months of banging my head against the wall about a very slight but annoying problem im having, im going to ask this question because I cant find the answer anywhere.

for various years of C5's auto or 6 speed, why does it matter which alternator is on the car? I have a 2004 A4 car and had a brand new alternator taken apart and the case powdercoated and then put back together by Metron Chrome (who I guess is no longer in business). I get a very slight flicker in my lights and the voltage seems to move around allot from between 13.7 volts all the way up to 15.1. it seems to be worse when there is more draw on the system like having the AC on. I had the ground checked and I dont have any grounding problems. I took the alternator off and cleaned off the powercoating where everything touches because I was told it grounds thru the bracket, then onto the engine block.

I really dont want to have to buy another A4 alternator just to check to see if thats the problem. can any year one work? and if so, I remember reading somewhere that the M6 alternators can be taken apart for painting or coating easier than the A4 ones due to the clutch pulley and some epoxied internals on the A4 one.


bottom line is the bare aluminum one will ruin the look under the hood, and I really dont want to do that, but the slight flicker is very annoying.


anyone got any ideas? maybe Bill Curlee can shed some light.

 

Try this:

TEMPORALILY install a 10 ga wire that runs from the BATT connection terminal on the BACK of the alternator to the POSITIVE battery terninal on the battery and see if your issue goes away. If it does let me know.

BC

 

will give it a try maybe tonight if I can get some free time!

 

by george, that seems to have fixed it, or at least brought it down to a point where I dont get pissed off....

so whats the perma fix for this, run that wire permanently?

edit: part of the big 3 upgrade?

 

You must have a bad connection or wire on that side of the alternator. The extra wire masks the problem, the alternator has an alternate path to use with the wire.

 

Waiting to hear Bill Curlee's solution.

 

Now that it seems you have a wire issue- just an FYI

You can rebuild the alternator for around $25 which includes the brushes (#1 reason alternators fluxuate, the brushes are worn) and internal voltage regular (#2 reason).

Especially since you've done some bling to the shell. Easy fix in the future.

 

I was told the auto clutch alternator needs to be epoxied on part of the electronics. But the manual one can be taken apart with ease.

 

 

That may be, I haven't done a auto C5- done a handfull of cars in my day.

 

That BATT wire on the back of the alternator goes to the STARTER SOLENOID and from that stud goes to the battery. So,,,,,,,,you have a poor connection at the starter solenoid stud:



There are multiple red wires on that terminal and there damaged or very corroded. Remove them, examine them clean them and reinstall them. I recommend some anti corrosion compound be applied (NOT SILICONE Dielectric grease!!! )

BC

 

is that picture taken from the underside or the top? doubtful I have corrosion (as the car has never really been in the elements and gets cleaned from stem to stern often), but very possible damaged from the person that installed my electric water pump and messed some other electrical stuff up....

thanks Bill for your insight! I hope to have it all fixed before Cruise In!

 

You dont know GM Delphi electronice very well do you! All it takes is One drop of water and a loose connection and you will have this issue. Your best bet is to jack the car and remove the nut and clean it.

It could also be the batt terminals or the connection on the back of the alternator.

BC

 

battery terminals have been replaced by gold plated blocks to allow for audio connections....back of alternator is spotless....got to be under the car then....I will see if i can get my pudgey azz under the car to locate it....

 

They may be gold but are your battery cable terminals PROPERLY tightened to the battery???

The OEM battery terninals must be tightened to 11 ft/lbs to be correctly connected to the battery.

BC

 

got me there..... i will check em all.....

 

Back when Design Specialties was still in business I had Aaron chrome and paint a new alternator for my 1999 six-speed.

When I installed it I had very similar issues to what you describe and went round and round with Aaron about it and we were very puzzled and frustrated because this was a new alternator.

Almost as a last resort I removed the alternator and also removed the plastic cover on the back (part of what was painted) and discovered three nuts under that plastic cover. One of them was loose and when I tightened it and reinstalled the alternator my issue went away.

I told Aaron of my discovery and at first he did not believe me as how could a new alternator have that issue. About two weeks later Aaron contacted me again to say he had encountered another new alternator that had one of those nuts loosened up indicating this is a possibility for new alternators.

Not sure if the A4 version of the alternator has these nuts under the back cover but it might be worth a look.

Best of luck with this issue.

 

I will check that too....thanks!