not sure if im missing something but the fact it starts your old motor and not your new one seems to indicate that the battery or wire is not at fault..

Unless of course your new starter motor is bigger meaning it needs more power to start?

Do you have a way of testing the new strater outside of the car?

seems strange that you old one tries to work

maybe this can help?

https://www.wikihow.com/Test-a-Car-Starter Regards

Daz

-------------------------
2011 (61plate) 4.4 tdv8
sumatra black

previous cars

e46 m3
e53 x5

The solenoid on the new starter isn't operating via the wire from the relay but did when jumper leads were used, indicating that the new solenoid must be requiring more current than the original to operate but the resistance in the wire is too great to provide the required current (the high resistance section will be getting hot!). As original starters have been burning their solenoid contacts, it is not surprising that a later version starter is fitted with a heavier duty solenoid so that the contacts aren't so readily burnt.

Thanks Dazza,

Yeah the fact it starts the old and not the new has had me scratching my head!

I’ve tested the new starter out of the car no problems and also now in the car. I took the ignition wire off and ran a direct feed to the battery. The starter turned over no problems when I did this. Like Graeme said, the new one must need more power for it to operate the solenoid.
Im low on time at the moment but hope to be able to run the new wire from the starter relay by the end of the weekend. I think I’ll just replace the starter too while I’m there doing the wire as it has done 55,000 miles on that starter. Going up into the Highlands this winter so don’t want to risk getting stuck.

GraemeS wrote:

The wiring schematic shows for the wire run:

starter solenoid
2.5mm2 2870mm
connector
2.5mm2 1165mm
solder joint
4.0mm2 1165mm
connector
4.0mm2 855mm
relay

No wonder there's significant voltage drop under load.

A 4.0mm2 direct replacement might only be 2m long.

White with purple stripe (WP) at the starter but then red (R) the rest of the way to the relay.

Thanks mate! Helps me a lot!  Oz

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