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2004 R1150RT Alternator Problem

Do you happen to have the years involved with the different starters? My old 98 Saturn has the bad design but after 188K no problems. It's my 03 R1150RT that has me a bit worried. How common is the magnet problem?

Sorry PAS, no idea where and when BMW used the D6RA-55 Valeo part. I do know for sure that my '96 RT had one in it and in '95 and '96 they were failing frequently. It is very easy to check though. If the part number label is not visible pulling the starter from an oilhead is very easy once you figure out the right angle to wiggle it out of there. No matter which one you have it's also a good idea to pull it every year or so and clean out the bendix gear, nose bushing etc. and lightly lube it. While you are in there with the starter out of the way you can also measure clutch wear and spline wear.
 
Success.

There were two separate problems:

1. The D+ spade terminal at the alternator was loose. Tightened up and reinstalled and the alternator starts first time, every time.

2. The starter motor was binding sometimes, drawing lots of current and causing the battery voltage to drop during cranking. This also means the injectors don't fire enough fuel, causing it to crank longer before starting.

Took the starter out and broke it down, in pieces. The model is D6RA75 which I believe is the "good" one.

What I've found is that the inside cover to the planetary gear system had somehow fallen out from it's location covering the gears. It then ended up attracted to the permanent magnets and found its way to the top of the armature. The piece I'm referring to is the cover you can see in the (copied photo from another post) picture below. It has been rotating with the armature, part of the inner hole has worn off and there are signs of arcing (including some holes in the cover!) but otherwise it looks fine. The armature wiring that made contact with the cover had some wear but is okay.

I reinstalled the planetary gear cover as in the photo below, put the starter back together after a bit of lubrication and cleaning. The motor now spins faster, is quieter and the battery voltage stays higher during cranking. The bike starts more quickly too.

Thanks everyone for the help.

DSCN6810.jpg
 
Well done Roger. No parts! :thumb

If you had taken it to an average shop, you'd have a new battery, new starter, and they never would have found the loose field connection.
I may be cynical, but I have good reasons.
 
Mike,
What voltage were you getting at the starter with the bad starter? Did you happen to recheck it with the new one? I am wondering what the voltage would be if the starter is ok.


Bruce
 
Mike,
What voltage were you getting at the starter with the bad starter? Did you happen to recheck it with the new one? I am wondering what the voltage would be if the starter is ok.


Bruce


I don't remember the voltage, just that it was only slightly higher using a much bigger battery.
That told me that my bike battery was not the problem.
I had already eliminated poor connections.

The problem is that "slow cranking" can be caused by both a weak battery, and a starter that draws more than it should.
Simply measuring voltage at the starter doesn't tell the whole story, you need to know how much electrical power the starter is consuming compared to how much mechanical power it is producing. Difficult to do with what most of us have around the garage.

What I did wasn't much better than a guess, effectively replace the battery and see what happens.

10V is generally accepted as reasonable battery voltage while cranking, it will be less at the starter.
 
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