QUESTION
I have just fitted a new voltage regulator to the rear of the Valeo alternator on my Lotus Esprit turbo.
After having changed the voltage regulator I still have the same problem where I can measure 18volts at the alternator.
This voltage is not constant but varies with engine speed.
Can you offer some advice how to solve this problem?
B.J. - Purpengary, Queensland
ANSWER
There are a number of quick checks that should be carried out to resolve this problem.
1) Check the condition of the fasteners and terminations at both ends of the heavy duty cable (brown insulation colour) that runs from the alternator stud to the starter motor solenoid connection.
This cable is subject to vibration and from experience can fray creating a poor conductive path which will limit current flow.
If necessary fit new cable terminations at both ends and secure by soft soldering.
Inspect, clean terminations and if necessary install new fasteners to ensure a good conductive connection at either end of the heavy duty cable.
Any voltage drop down this cable will cause the voltage to rise at the alternator terminal.
2) Check the earth continuity between the alternator casing and engine cylinder block.
This needs to be carried with a DVM where the meter is set to check the static resistance path between the alternator and alloy cylinder block.
A second check should be carried out with a DVM where the meter is set to check voltage drop between the alternator and alloy cylinder block.
It is necessary to run the engine and turn on the headlamps to carry out this test.
If resistance or a voltage drop is detected, then the alternator 8mm pivot spindle should be removed, cleaned and coated with anti-seize compound to ensure a good conductive path (zero resistance and zero voltage drop)
3) With the voltage regulator removed from the back of the alternator, connect a DVM across the two terminals exposed inside.
The DVM should show a low resistance reading that indicates the internal carbon brushes are not worn and are making contact with the control armature.
If the above procedures fail to resolve the over voltage problem, then the alternator should be removed from the Lotus Esprit and bench tested.
Copyright © 2013 Lotus Marques
I have just fitted a new voltage regulator to the rear of the Valeo alternator on my Lotus Esprit turbo.
After having changed the voltage regulator I still have the same problem where I can measure 18volts at the alternator.
This voltage is not constant but varies with engine speed.
Can you offer some advice how to solve this problem?
B.J. - Purpengary, Queensland
ANSWER
There are a number of quick checks that should be carried out to resolve this problem.
1) Check the condition of the fasteners and terminations at both ends of the heavy duty cable (brown insulation colour) that runs from the alternator stud to the starter motor solenoid connection.
This cable is subject to vibration and from experience can fray creating a poor conductive path which will limit current flow.
If necessary fit new cable terminations at both ends and secure by soft soldering.
Inspect, clean terminations and if necessary install new fasteners to ensure a good conductive connection at either end of the heavy duty cable.
Any voltage drop down this cable will cause the voltage to rise at the alternator terminal.
2) Check the earth continuity between the alternator casing and engine cylinder block.
This needs to be carried with a DVM where the meter is set to check the static resistance path between the alternator and alloy cylinder block.
A second check should be carried out with a DVM where the meter is set to check voltage drop between the alternator and alloy cylinder block.
It is necessary to run the engine and turn on the headlamps to carry out this test.
If resistance or a voltage drop is detected, then the alternator 8mm pivot spindle should be removed, cleaned and coated with anti-seize compound to ensure a good conductive path (zero resistance and zero voltage drop)
3) With the voltage regulator removed from the back of the alternator, connect a DVM across the two terminals exposed inside.
The DVM should show a low resistance reading that indicates the internal carbon brushes are not worn and are making contact with the control armature.
If the above procedures fail to resolve the over voltage problem, then the alternator should be removed from the Lotus Esprit and bench tested.
Copyright © 2013 Lotus Marques