I have a rebuilt 77 CJ7 with 304 engine. It has had this problem on and off for over a year now. I am not able to diagnose why the engine just clicks. Does not turn over. The battery reads 12.1 volts. Just clicks when I turn the key. Jumping it produces 14.0 volt reading at both the battery and starter solenoid. Still just clicks. Checked all connections and they seem tight. Battery, starting solenoid, starter, ground. Would this be a bad starter? What else should I check to get this to turn over. Thank you

Check voltage at the battery terminal of the starter relay. 12V? Good. Not 12V? Replace that cable. Next, while someone cranks the key check voltage at the output terminal of the starter relay. 12V? Good. Not 12V? Replace the relay. Next check voltage at the input terminal of the starter, while someone cranks the key. 12V? Good. Not 12V? Replace that cable. If you get to this point, and everything is good - replace the starter. mtm

Just getting 12v at the end of the cable isn’t an indicator that the cable is good.  It has to carry 120 amps to make the starter crank the engine. OTOH, not getting 12v may be to poor contact and not a defective cable.

 

Roger

 

you can always eliminate ( or confirm) wiring by touching a spare power source (battery, charger, etc) directly to the starter. Take care not to run yourself over. Too much. Also try giving the start a few whacks with a mallet to free the brushes/ armature.   I also recall someone saying that shimming on the starter mount can help: if it's cocked just a tad it'll just twist itself further off axis.   Roger's absolutly right. If you need an excuse to buy more tools, an infrared thermometer and a clamp on ammeter are nice to have, and might help in diagnosing this, to boot. 

Clean the battery terminals first.  Could be the solenoid is bad.

 

Roger

 

Yeah, I stand corrected. I' just an idiot. Better listen to these smart people. They'll have you stuck in no time. Buy lots of tools, ignore the basics, make everything harder than it has to be. Why didn't I think of that? But then, I'm just a mechanic. Kiss my simple ass. mtm

Come on guys. I learn when someone tells me how to check it. I learn when someone tells me more information.
Like the bumper sticker "shit it was only a lane change"..... at least nobody said "take the starter to vato zone and bench test it" as a complete answer.
 
 Dan   Note: Readers with allergies to spelling and grammar errors beware !

 Maybe you want him to run 22 gauge wire for his battery cables since that will show 12v .  Ignore the basics?  That IS the basic, but that’s just what the electrical engineers tell me.

 

Clean the terminals and give it a try. If that doesn't work I would say that the starter is just sticking. Traditionally when a starter solenoid is bad it either works or it doesn't. Try what an earlier poster said. Try whacking the starter with a mallet dead blow, or a piece of wood. Be careful not to damage the starter. That should loosen up everything inside and allow it to engage properly. Good luck