starter motor teeth? 11 or 9?

[omodos]

Hello all again, gonna take the plunge and get the starter replaced , but for the life of me (and I have not to asked mechanic to remove it yet as still works) I can't figure out if it has 11 teeth or 9, real oem just doesn't mention it.


Onlilne site I found with prices that are acceptable lists 26 different matching brands for BMW oem 12417788680 (that is made by denso on my model x5)


BUT none of them can tell me if I need a 11 teeth starter or 9....anybody have a clue at all much appreciated, buying from a local retailer is nearly twice the price I can get it onlilne from germany of all places......any any tips much appreciated. here is the link showing types



https://www.autodoc.co.uk/spares-sea...rd=12417788680

[wpoll]

Given that the 12-tooth would spin the motor faster but with less torque than the 9-tooth, and you have a diesel, I'd guess that the diesel models use the 9-tooth and the petrol models use the 12-tooth.

[omodos]

Thanks i will find an answer soon....last test before i start to swap things out is run jumper cable from ground lug on chassis in engine bay to metal part on engine block...see if that improves starter speed....if yes apparently have a bad ground somewhere

[oldskewel]

Originally Posted by wpoll

Given that the 12-tooth would spin the motor faster but with less torque than the 9-tooth, and you have a diesel, I'd guess that the diesel models use the 9-tooth and the petrol models use the 12-tooth.

Logic on the torque vs. # of teeth makes perfect sense. But I'll add that the starter in my 2001 3.0i (US, gasoline version) seems to be completely different from this, rather than the same thing with a different pinion gear. Mine is a Bosch.

So, NOT for the 3.0d, but for my 3.0i:

Part numbers: BMW 12-41-7-501-738 (although on the original part itself, next to the BMW logo, it says 7 501 668 ???). Bosch PN: SR-0474-N. On the starter shell itself (original, with a 2001 date on it, made in Germany): Bosch 0 001 108 190. Photo below.

So yeah, even with the original part in hand, sometimes numbers don't exactly match with what they "should" be. I don't have any pics of my pinion gear (not that it would really help on a 3.0d), but somehow I remember it having 9 teeth.

When I had everything apart earlier this year, I inspected and cleaned things up and replaced the brushes assembly in it (4 brushes still had about 70% life left in them at 186k miles, so it was definitely an optional repair I did). That starter is a beast, much like just about everything else I came across on this engine.

[omodos]

Greatly appreciate reply and your time...wots in mine is a denso...tomorrow if i can will try one last tip i have seen to eliminate bad ground causing my issue...hook up jump cable from negative in engine bay to metal part of engine...n try starting

[wpoll]

Originally Posted by omodos

Greatly appreciate reply and your time...wots in mine is a denso...tomorrow if i can will try one last tip i have seen to eliminate bad ground causing my issue...hook up jump cable from negative in engine bay to metal part of engine...n try starting

If you are seeing 392amps you don't have a bad earth!!

[omodos]

Wpoll cheers...amazing how i can get tips advice from all corners of the globe.....the 392 amps i got was a negative figure cos i had damn amp clamp on wrong end of battery cable.l when testing....so need to do test again i guess....right the bad ground seen it on many posys here n there that bad ground can cuase odd gremlins...moreso on x3s where a groundin strap perishes....you have any clue where they are om the X?

[wpoll]

Originally Posted by omodos

Wpoll cheers...amazing how i can tips advice from all vorners of the globe.....the 392 amps i got was a negative figure cos i had damn amp clamp on wrong end of battery cable.l when testing....so need to do test again i guess....right the bad ground seen it on many posys here n there that bad ground can cuase odd gremlins...moreso on x3s where a groundin strap perishes....you have any clue where they are om the X?

Sorry, omodos, I wasn't meaning that the polarity was relevant (it isn't) - I meant that if you measure 392 amps (or -392 amps) then the circuit must be very good.

A bad earth would limit the current to the starter motor, acting as a series resistor and dropping the voltage across the starter motor.

The fact you see a current as high as 392 amps indicates that the circuit from the battery to the starter motor and back to the battery is very good. Ohms law tells me that if your battery is 12 volts (nominal) then the entire circuit resistance (including all cables, earth straps, starter motor and starter motor solenoid) must has a total resistance of 0.03 Ohms - very low indeed.

If 392 amps though the starter motor isn't turning it as fast as it should be, the fault will be in the starter motor (most likely a seized armature or bearings).

[omodos]

wpoll cheers for reply, I need a massive favour seeing as you have 3.0D as well and the facelift, from time you turn to turn key to on position how fast does it fire up? can you hear the starter spinning fast?(IF you could get an audio clip would be superb but that is asking alot)

Also good to know that the polarity doesn't make a difference when an amp clamp test is done, your explanation is very sound and I am by no means up to speed on these matters, but what confuses me is I read and see various articles and posts that say a bad ground may lead to excessive amp draw on starter ....is my thinking ok to try and get a jump lead from the bolt (-ve) on the inside of the wing in the engine bay and attach it to a metal part of engine , turn to on as a test? sorry to be so pigheaded after you saying I don't have a ground issue.

[wpoll]

Happy to help - if I can. I'll make a audio recording in the morning. It will be cold - 6DegC. or so - but I expect that the car will start almost instantly. It almost always does.

Adding the jumper lead cannot hurt and would likely bypass any earth problem that might exist between the body and the engine.

Anyone that says that poor earth connections can cause high currents doesnt understand Ohms law and basic physics, although poor earth connections have been known to create alternative high current paths via circuits not intended to carry high currents. This doesn't usually end well...

And you aren't being pig-headed - just thorough. ;-)