Post by valhalla on Mar 3, 2015 1:23:40 GMT 1
That's a question I have already asked myself, the answer is I'm not so sure now. The original starter motor is still in-stock somewhere in the workshop (it was never returned, as the suspected fault on it was for the solenoid, not the motor itself) and therefore I have some means to getting the answer. What I can say is that the replacement motor/solenoid was supposed to be a like-for-like against the original motor part number, but if memory serves me correctly, it was supplied as a remanufactured unit from a specialist in the Midlands, and therefore cannot be assured to function as it should (in my mind, anyway). The crucial thing with this model is that the solenoid feed terminal is unique to this application, so a majority of the aftermarket units would just not fit at the time.
If the customer is correct, then the symptom of the problem has not altered between "original" and "new" motors, but I have to give the owners the benefit of doubt here; the motor was replaced last Winter, the problems went away, then they have re-surfaced this Winter after a while - they say that the symptom is the same, but a year is a long time.
I am working on the assumption that whatever was wrong with the car has remained wrong with the car, and the starter motor is unlikely to be the root cause of the issues, albeit that it has some strange behaviours. Given that I want to get to the bottom of this problem as soon as possible before the warm weather arrives, I may well take the punt and refit the old motor to re-measure some of these characteristics. In particular, what I'm most interested in is the current draw during the initial crank, but also something else that seems to occur as the solenoid operates. I will try to attach a screenshot of the solenoid/relay induced currents prior to the motor turning - they seem aggressive, much more than normal, and I hope they are measurement error and not too real. If I can get hold of a new genuine VW relay in the next day or two (for the right money) I'm going to give that a go before ordering a new battery, just to see if that tidies-up the spikes in voltage and current. Maybe the old motor/solenoid will not have the same characteristic?
The channels shown in the PDF are (red = starter motor +ve feed current) (brown = starter motor earth at fixing bolt/cable terminal, relative to battery -ve terminal)
Attachment Deleted
If the customer is correct, then the symptom of the problem has not altered between "original" and "new" motors, but I have to give the owners the benefit of doubt here; the motor was replaced last Winter, the problems went away, then they have re-surfaced this Winter after a while - they say that the symptom is the same, but a year is a long time.
I am working on the assumption that whatever was wrong with the car has remained wrong with the car, and the starter motor is unlikely to be the root cause of the issues, albeit that it has some strange behaviours. Given that I want to get to the bottom of this problem as soon as possible before the warm weather arrives, I may well take the punt and refit the old motor to re-measure some of these characteristics. In particular, what I'm most interested in is the current draw during the initial crank, but also something else that seems to occur as the solenoid operates. I will try to attach a screenshot of the solenoid/relay induced currents prior to the motor turning - they seem aggressive, much more than normal, and I hope they are measurement error and not too real. If I can get hold of a new genuine VW relay in the next day or two (for the right money) I'm going to give that a go before ordering a new battery, just to see if that tidies-up the spikes in voltage and current. Maybe the old motor/solenoid will not have the same characteristic?
The channels shown in the PDF are (red = starter motor +ve feed current) (brown = starter motor earth at fixing bolt/cable terminal, relative to battery -ve terminal)
Attachment Deleted