924Board.org

[jdub]

Hi
every few weeks i need to replace the alternator's regulator. i thought i was because i was getting cheaper ones, but now my German one seems to be getting weak. (battery light comes on when not at higher revs- then within a couple days, no charge at all to battery from Alt. then when i replace regulator its good for a few weeks). It hasnt been the Batteries- they test good when this happens).

Any ideas or experience with this?
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81 924 non-turbo

[Rasta Monsta]

Wiring fault. Best practice is to replace alternator and battery harnesses, and add heavy duty ground cable from engine to chassis.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[musicalannette]

I think your probably right.

there is a set of wires which go from the battery down behind the engine in a loom to the alternator/starter. If they melt, it can cause all sorts of weird faults. Be careful to replace them with high temperature capable insulated wire.
Also make sure you have the heat shielding.

if your not in a rush and don't want to replace the alternator out straight away then:

Alternators can breakdown/wear out.

check the brushes are making a good contact and there is plenty left, but at the small cost, replace if you can.

equally, get it(the whole alternator) hot (in an oven at 60/70 deg C) and then check the winding resistances and if you can the inductance. if there the same as is cold then all should be good and it might save you buying a whole new alternator.

hope this helps.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[!tom]

Also, an old battery can overload your alternator, leading to short alternator life. Probably not your particular problem, but something to consider and keep in mind.
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78 924 NA
5-lug

[ideola]

To bolster the wiring fault idea, if you are having sporadic interruption of the circuit while the alternator is running, it WILL wipe out the regulator. One of my race customers couldn't figure out why his race car kept blowing out alternators. When I asked him how he had his emergency shut off wired, and he revealed that he was using that to kill ignition (rather than shutting the car off with the ignition switch first), we found his problem. Also, a lot of old school guys will lift the ground on the battery while the car is running in an attempt to confirm that the alt is producing voltage. Bad idea, as it will destroy the voltage regulator.

On naturally aspirated 924, the main battery/alternator harness is highly susceptible to heat fatigue due to its proximity to the exhaust manifold / downpipe. It's highly likely that you have a fault in that portion of the wiring loom. So I strongly "third" what Rasta and Musical have suggested: remove that loom entirely, and rebuild it with heavier gauge fresh wire. Put it into a firebraid sleeve upon reinstallation.
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erstwhile owner of just about every 924 variant ever made

[jdub]

will do
thanks
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81 924 non-turbo