Alternator Problems

[mkhadir]

Hello all

I recently had my alternator replaced.  After this the alternator light used to come on at idle (sitting at the traffic lights). If I revved the engine it went off.  So I thought that it might need a smaller pulley - so I went back to the mechanic and he replaced the pulley with a smaller one.  No problems with the light coming on at idle.  But this only lasted two days - Now the alternator light comes on during driving only - it flickers from faint to bright during driving.  When I come to a stop it goes off!

Any thoughts?

Cheers
Mubeen
'66 230SL Auto
Melbourne, Australia

mubeen
melbourne, australia
1966 230SL auto, ps

[J. Huber]

I'm not one of the experts, but I believe sometimes the red light will come on if the idle is too low (thus it goes away when the engine is revved up). I would say this is not a sign of a bad alternator but rather an indication that the car needs to be tuned or timed a little.

James
63 230SL

[George Des]

May be time to check the voltage regulator on the inside of engine compartment mounted on fender. Also, check to make sure your grounds are attached to clean metal.

George Des

[mkhadir]

Replaced the voltage regulator.  Looks like the problem is almost fixed!!! - Now the alternator ocassionally light flickers when I go over bumps only.  Very strange. Any thoughts??

quote:Originally posted by George Des

May be time to check the voltage regulator on the inside of engine compartment mounted on fender. Also, check to make sure your grounds are attached to clean metal.

George Des

mubeen
melbourne, australia
1966 230SL auto, ps

[hands_aus]

loose earth wire somewhere?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[al_lieffring]

There is a possibility that this condition could be caused by voltage drop in the heavy gage charging wires.
I just replaced the 10 gage wire going from the alt to the starter on my 230sl.
Check for frayed or corroded cables and terminals going from the alternator to the starter or at the connections inside the car.
I have seen this condition in 280sl's caused by corroded connections at the headlight switch, I dont think the 230 uses this terminal as the main power suply for inside the car though, check at the back of the fuse box and the ignition switch.
When checking screw-on wire terminals dont just tighten down the screw tighter, take the screw loose and inspect the ring terminals for corrosion.
Also was the ground strap attached to the alternator when the new one was installed?

113-042-10-014715
built 11 Jan 66
904/396 blue, Ivory Tex
condition- rust bucket

[J. Huber]

quote:Originally posted by J. Huber

I'm not one of the experts, but I believe sometimes the red light will come on if the idle is too low (thus it goes away when the engine is revved up). I would say this is not a sign of a bad alternator but rather an indication that the car needs to be tuned or timed a little.

James
63 230SL

Ok since I swung and missed badly on this one, I have a couple questions...

1. If the red light comes on and the idle is fluctuating from normal to low, are these two things not related?

2. Is the red light designed to tell us the alternator is ailing or only that the voltage regulator is bad?

I ask because my red light now comes on for a moment at cold start-up. The rpms are also a bit unsteady right after start-up. The red light goes off after revving engine or starting to drive. The rpms soon level off as well and are steady when warm. Two separate issues?

James
63 230SL

[mkhadir]

I believe the red light is designed to tell you if the battery is not charging - which could be a problem with the alternator or the regulator.

I think its a wiring problem on my car.  Have decided to keep driving for a few more days to how much of a problem it is and then take it back to the mechanic to check all the wiring.

Cheers

quote:Originally posted by J. Huber

quote:Originally posted by J. Huber

I'm not one of the experts, but I believe sometimes the red light will come on if the idle is too low (thus it goes away when the engine is revved up). I would say this is not a sign of a bad alternator but rather an indication that the car needs to be tuned or timed a little.

James
63 230SL

Ok since I swung and missed badly on this one, I have a couple questions...

1. If the red light comes on and the idle is fluctuating from normal to low, are these two things not related?

2. Is the red light designed to tell us the alternator is ailing or only that the voltage regulator is bad?

I ask because my red light now comes on for a moment at cold start-up. The rpms are also a bit unsteady right after start-up. The red light goes off after revving engine or starting to drive. The rpms soon level off as well and are steady when warm. Two separate issues?

James
63 230SL

mubeen
melbourne, australia
1966 230SL auto, ps

[hands_aus]

quote:Originally posted by mkhadir

I believe the red light is designed to tell you if the battery is not charging - which could be a problem with the alternator or the regulator.

I think its a wiring problem on my car.  Have decided to keep driving for a few more days to how much of a problem it is and then take it back to the mechanic to check all the wiring.

Cheers

quote:Originally posted by J. Huber

quote:Originally posted by J. Huber

I'm not one of the experts, but I believe sometimes the red light will come on if the idle is too low (thus it goes away when the engine is revved up). I would say this is not a sign of a bad alternator but rather an indication that the car needs to be tuned or timed a little.

James
63 230SL

Ok since I swung and missed badly on this one, I have a couple questions...

1. If the red light comes on and the idle is fluctuating from normal to low, are these two things not related?

2. Is the red light designed to tell us the alternator is ailing or only that the voltage regulator is bad?

I ask because my red light now comes on for a moment at cold start-up. The rpms are also a bit unsteady right after start-up. The red light goes off after revving engine or starting to drive. The rpms soon level off as well and are steady when warm. Two separate issues?

James
63 230SL

mubeen
melbourne, australia
1966 230SL auto, ps

There is a loop back when a diode is blown. The red light will come on and stay on when the ignition is turned off.
This indicates that voltage is being applied to the rotor winding and eventually your battery will be flat.
To continue using the car with reduced charging you can disconnect the battery when the engine is turned off.
I did this for a couple of weeks before finding time to have the original alternator rebuilt.
Everything is back to normal after the diode module was replaced. The external regulator works fine so was not replaced.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto