cheap alternator replacement

just finished changing alternators on my TDI, but should apply to most A3/S3
oem fitting is valeo or bosch, interchangeable, the bosch is a better unit as its a lot easier to change the bearings/brushes etc
bosch have been making the same basic unit for years, and are fitted across the whole range of engines
looking at the dimensions for one from a 2012 Passat tdi, it looked the same, but a lot higher current rating, I chose this one as it was on ebay when I was looking for a new unit

I took a punt on it as it was only £35, it did fit but the connection for the regulator was different, but being a bosch, a new regulator from an earlier model is a direct fit and has the correct connector.

so for about £50, I got a virtually new bosch 130A alternator, saving over £100 on the best price I've seen for these.
here's a picture of it in its new home, those of an OCD nature should not look at the rest of the engine bay

nope, only supplies the current that it needs to, but the electronics are a bit beefier, so should last longer,
not that 10 years on the old one was a bad run

doesn't really affect the battery as long as the output voltage of the alternator is the same, a fully discharged battery will charge at around 30 to 40 amps, the capacity of the alternator to supply 130A does not change this.

where the extra capacity may help is crawling along in traffic at low engine speed, in the dark and cold with lights on, heater on full blast, heated rear window on , wipers on, should be able to maintain the voltage a bit better,

but I haven't had those sort of issues since cars changed from dynamo's to alternators

if it does its a bonus, the goal was to try to score a cheaper replacement alternator, which I did

I can, but you already know that

the rating of the alt is the maximum it can supply, it will not just dump 140A into the car,
it will only supply what the car is demanding.
as long as it is physically the same (ie fits in the available space, bolts holes same , pulley the same), and the sense plug is the same (check this very carefully, there are two little ribs inside the socket on the alt) you should be good to go.

the only issue I can see is that IF the car was demanding 140A, the cable from the alt to the battery could have been undersized, IF it had been sized at 90A, but its not, that cable looks well capable of 140A

I had mine on since I first posted this with no probs

hope this helps/m

mr slag

a little light reading

http://cartech.about.com/od/Power/fl/High-Amp-Alternator-Damage.htm