intermittent drop in voltage and juddering. help???

[GasDoc]

I've re-entered this discussion as new info has come to light. Initially thought problem related to a fuel refill following a near empty tank but this is probably a red herring. My 500 starts OK. Voltmeter on dash reads 13. After a short while when up to usual running temp (70deg C)the voltage drops to 11 and the car starts juddering/hesitating. Doesn't actually cut out but feels as though it will. At one point it briefly returned to 13 and ran OK for about a minute, then did the same again. When I went to start it this morning, the battery was flat. Trickle charged it, started it again this afternoon, and same problem. The charging light doesn't light when the voltage drops, and there doesn't seem to be a problem with the drive belt to the alternator/water pump. Car being hospitalised tomorrow so hopefully I will have an answer.
Has this happened to anyone else/any solutions?
thanks
Rob

[shpub]

100AMP alternator fuse?

[GreenV8S]

shpub said:

100AMP alternator fuse?

That would be my guess.

[GasDoc]

thanks for the replies. Will let you know if this rectifies the problem.
Rob

[Pasco]

Rob to prove this join the cables together each side of the 100 amp fuse and drive the car again.
Having said that when my 100 amp fuse started playing up it did put the light up on the dash.

Pasco

[GasDoc]

Thanks for the replies. 100 amp fuse was OK, alternator wasn't. Was getting hot when it shouldn't be, and was making a quiet buzzing noise at standstill with the engine and electrics off. Presumably the battery was discharging into the alternator and heating it up. Replacement alternator seems to have cured the problem.

[Pasco]

GasDoc said:

Thanks for the replies. 100 amp fuse was OK, alternator wasn't. Was getting hot when it shouldn't be, and was making a quiet buzzing noise at standstill with the engine and electrics off. Presumably the battery was discharging into the alternator and heating it up. Replacement alternator seems to have cured the problem.

Thanks for letting us know the outcome GasDoc wonder why the orange light was not lit up

[David H]

GasDoc said:

Thanks for the replies. 100 amp fuse was OK, alternator wasn't. Was getting hot when it shouldn't be, and was making a quiet buzzing noise at standstill with the engine and electrics off. Presumably the battery was discharging into the alternator and heating it up. Replacement alternator seems to have cured the problem.

Sorry Doc, I'm a bit late seeing this thread. I had the same problem, it was also the alternator.

Glad you got it sorted