hey i think my starter may be going bad what do you guys think? it all started at school when it wouldnt crank and then after like 5 mintues it did. so when i got it home it wouldnt start again and i charged the battery and then it still wouldnt start, got a volt reading of about 9 so i then tried to jumpstart it with my sisters car and it wouldnt crank either, this the voltage raead 13. so after all this im thinking its the starter, im gonna hit it with a hammer tomorow and see if it starts but if it doesnt im just gonna change the starter, good idead or bad?

 

Sounds more like a bad batt or connection.

Make sure the batt cables are clean and tight.
Check ground at eng too.

Do you hear a click from the starter when attempting to start?

If your batt was at 9 volts when trying to jumpstart, your batt may have been soaking up most of the power your sisters car was delivering.

Make sure your getting a good connection with the voltmeter.
If the batt voltage was 9 volts after charging, it's a goner.
If it was 9 volts before charging, it's at least damaged.

Try checking batt voltage while trying to engage the starter.
With a good starting system, you should be able to crank for 20 seconds and batt voltage should not drop to below 9 volts.

Swap your battery with a known good batt if you can.

If you get the eng started, check batt voltage with eng running and compare it to batt voltage with eng off. That will tell you if the alternator is working.