Alternator Diodes question

[StockoVRWagz]

Over a year ago I had a problem of the battery draining back through the alternator. I found on here that it was most likey faulty diodes in the alternator. The problem fixed itself (as they do lol) and I never had the battery drain again. Last week, the battery went flat, so I checked it with a multi-meter and found the battery drain is back. The next day, after charging the battery, I checked it again and the drain had disappeard again.

Would a dodgy diode do this, or would it not 'fix' itself?
The drain when it is there is 3.2 instead of 0.02
No lights on, all fuses pulled, drain stops when the alternator is unplugged (the plug on the back of it) or when the trace wire from the +ve terminal is disconnected.

I just can't afford to put it in a shop and be told there's nothing worng again, or buy an alternator just to find that's not the problem (sick children = $$$$ lol)

Cheers,
Paul.

(I had a post on this early last year, but didn't want to dig up the old thread)

[hako]

I don't have a diagram for the VR V8 so where does the "trace" wire go to ?
What brand alternator is it ?
Are the bearings noisy ?

[EvilOzzie]

Ever thought about just replacing the diodes?

[StockoVRWagz]

Bearings are fine, it charges perfectly. I have a diagram for the VR V8, I'll dig it up tomorrow and see where it goes to. As for the brand, its the stock one I think, again, I'll have a look before work when I have some light.

I thought the cost of the diodes would be around the same price for a recon alternator and not worth doing?

[hako]

If you have an aftermarket immobiliser I'd check that too as they can drain a battery quicktime. Diodes usually fail 100% and don't fix themselves unless the connector on the diode pack is dodgy so I'd figure diodes are OK. If one in the pack fails the first sign is usually a flat battery because the bad diode reduces the alternators ability to generate enough power to recharge the battery (plus the drain which can be a dead short or open circuit or something in between).

[axemurderer101]

have you tried disconnecting the reg plug and take off the batt lead from the alternator then check for and current draw again

[StockoVRWagz]

Sorry, haven't been able to look up that diagram, been busy with my son..

Regulator is new, the current draw stops when I unplug the regulator. I replaced it when the problem occured a year ago becaue I thought the regulator was shaggedand it made no difference.

I had an alarm fitteded by DodgyBarn which doesnt work anymore (died 6 months after being installed, been WAY to busy to give them my car so they can see if it's their fault + need the car for work grrrr) But this was happening before they touched the car. Also, the battery is good and holding charge, only 18 months old.

It's annoying having to disconnect the battery every time I park it lol.