Slow Crank and won't Jump Off...Please help

[gwp]

95 Maxima, 140K milesRecently I noticed it cranked very slow but started. Battery voltage was great, and alternator was charging. I cleaned battery posts (even though they didn't look dirty) and it then cranked normal. All well for the next several starts, then problem returned.....and finally wouldn't start at all. I tried jumper cables which didn't help at all. Any help very much appreciated.

[allensteiner]

is it still cranking? the battery voltage has little to do with starting the car - cranking amps do. get the battery checked at walmart or any parts store and if that one is good look into the starter and it's wiring.

[gwp]

It has now stopped cranking (turning over) at all. I dug down to the starter and tried to jump the solenoid and it wouldn't crank. I understand your point regarding amperage......I tried a battery I know is good and no difference. I guess the starter is the problem, but I have never seen a bad starter behave like this....slow crank. Thought they usually went completely out or the horrible sound of it grinded the ring gear. I guess I'll remove the starter and go that route. I read on this site of someone who successfully rebuilt one by replacing the brushes??? Anyone with ideas....I'd like to hear from you. Thanks much

[robo_geek]

Electric motors often fail because the insulation on the motor windings begins to break down, causing it to partly short internally...then it gets weak/slow.

[allensteiner]

i have the original starter in mine and no probs - guess i'm lucky. take yours in to a parts store and have it tested - most likely it'll just be a bad solenoid which is simple to replace and not costly (diy) - they can tell you exactly what's failing.