Battery vs.Alternator vs Starter???

[omodos]

Originally Posted by Harry.s.truman

I had an issue like this that snowballed.... In the end, I replaced the starter, battery & alternator....

All three were going... The main culprit was a corroded connection at the jump post under the hood... Cleaned that and it solved my issue, for the most part, but while I was charging, checking and diagnosing , I prob killed the starter and alternator...


Couldn't figure out that a bad connection was causing all these issues..

thats nuts, so the -ve and +ve jump points in engine bay were visibly rusted or somekind of salt deposit? and you simply cleaned and that was it?

[Harry.s.truman]

Originally Posted by omodos

thats nuts, so the -ve and +ve jump points in engine bay were visibly rusted or somekind of salt deposit? and you simply cleaned and that was it?

Nothing out of the ordinary... I guess from putting a jumper pack on and off for a month or 2 it must have corroded it enough to where it wasn't passing enough voltage to drive the starter....

It was just a little rusty... cleaned it with a wire brush and sandpaper and it fixed my starter issue..

[omodos]

jeez that is crazy, i had no idea the state of the jumper poles could impact the starting system, i thought they were there either to jump start or do trickle charge the battery, hmm will check mine too later maybe unbolt clean and put back on although they look very clean....very little rain ut here to cause rust

[Harry.s.truman]

crazy indeed, last place I would have checked but I was out of ideas..

[Bmwtvboy]

Da battery. All works fine now. On to the steering angle sensor.

[omodos]

following is interesting and I guess needs checking if both your battery is find and alternator is fine

3.0d battery/slow starting problem?? Read on pls

jist of it is a few people have mentioned this, and could well me my issue too

"X5's don't use Bosch starter motors , they use Magnetti Marelli , and with the earlier X5's , there was a big problem with them failing . I forget the complexities of the explanation , but basically their internal workings short out and cause the unit to draw far too much power from the battery .
Hence the reason it cranks over very slowly . They asked me to do a drop-test on the battery whilstturning the engine over . The readout should be around 180amps . It's the amp figure to look for ,NOT the volts .
So , last night I took it to a small garage I know and asked them to do a test for me . 370amps draw .Over twice what should be expected .

Around '05 , when my car was built , was when BMW acknowledged there was a problem and started to fit an upgraded starter motor "

again from another X5 owner same story:

"Interesting. I had all sorts of problems starting my E53 about three years ago with slow starting. I had some serious arguments with two BMW dealers about this and I ended up with the rear hatch power lock being changed because it was drawing too much power, no difference, then they blamed the iPod system and is was reinstalled, no difference, next the security device was blamed and a diode put in the power supply, again no difference but it wrecked the device.

After months of insisting that someone should stop using the fault diagnosis system and start working from 1st principles (the way I was taught to maintain cars) as they used before all these new fangled computer systems, finally one Dealer put one of their real mechanics ( not a Technician as they now call them ) on the car and he bactracked the problem to find that like you it was the starter motor drawing way too much current. Because of the fault and the length of the starter cables, there was such a volt drop that the system could not deliver the required current and the car's supply dropped to about 9V which caused the entire system to reset.

A new starter was fitted, and everything has been fine ever since. Because no fault code ever showed for it the garages had a real problem tracking it down as the whole car electronic infrastructure effectively crashed when the starter was engaged.

A useful tip for anyone else finding poor starting but a battery that tests as OK.