I have a 525i,2003,6 cyl,2.5 cc and the problem is that the starter dont work,knoking the solenoid sometimes start ok. I need to know the toolds i need to replace or repair this problem,what are the torch sizes etc .

Sounds like solenoid is getting stuck on .mite need to change your starter.

Possibly a battery cable terminal or the connection at the starter.
Sometimes a loose or faulty wire can barely work until a load is put on it then it just shuts down. Test power flow at starter before and after turning the key. Replace battery cable ends and if the problem persists, replace entire cable.

Kindly check this site.
Interior Fuse Box Location 1997 2003 BMW 525i 2001 BMW 525i 2 5L 6 Cyl...

Ok, those systems might still work because the not require as much energy as the starter. Check the Battery Voltage with a good Voltmeter. If below 12, there might be your problem!

rarely fail,but do.if the battery load tested out to be good . you get 12 volts to the starter signal wire when you turn the key to start. then the starter is bad or the engine or something driven by the belt is locked up.

Yes it could. The start solenoid has a large washer that has to make contact to flow the current the starter needs. Over time it gets covered with carbon and burn marks. These will eventually get so bad that they dont conduct the current necessary to make the starter crank. Technically you can just replace the solenoid but most shops wont and will insist that it is better to replace the whole starter. In many cases the labor will be the same and slightly more perhaps to repair the solenoid then to just replace the starter.
As you can see though either will fix the problem.

There's not much to go on here, but I will take a stab at it. Sometimes the starter solenoid wears out its electrical contact. This prevents power from activating the starter. This can be an intermittent problem. As the engine moves or cools, it could make contact again, and the starter will work. Remove your starter and have it tested. You can buy new contacts for the solenoid, or you can simply replace the starter assembly, and the new unit will have new solenoid contacts already installed.

sounds like battery or bad starter

check the solenoid on the starter it powers the ign for starting then switches to run when you let off key,either the solenoid is bad or a wire to the solenoid has come unhooked and sometime they have an in line fuse which can blow.

hi, when it dont turn over do you hear a clicking noise or is the engine turning over and just not starting.
If its the first and when you turn the key the starter motor dont turn the engine over allowing it to start you will usually hear a clicking noise and this is the selanoid inside the starter motor failing to make a connection.
If this is the case then all you need to do is get the starter motor replaced if you have any further comments or need further assistance then let me know ok