68 Z28 starter problem

[fireZ]

I tried to start my 68 Z today and the starter would not kick in and  turn engine. I pulled the starter and put cables on it and it worked good on the work bench. I put it back in the car turned the key and still just had a humm or buzz from under the hood.Any ideas? Thanks

[1968RSZ28]

Have you load tested the battery?  Are you able to turn the engine over by hand?

Paul

[tom]

How are the cables?

[fireZ]

The battery cables are good and I can turn the engine over by hand. This car was fired up 2 months ago and parked.

[Sauron327]

Connections: Junction block on radiator support behind firewall. Bussbar on V.R. and H.relay connections. Check all grounds. Check voltage at starter at rest and while keying to "start". What's the drop? 

[fireZ]

Should I get a 12 volt reading at the starter?

[Sauron327]

Best to do a search on "battery to starter voltage drop". You'll get many sites. Too much to list here. One thing: Testing the starter as you did will only tell you if it spins, not how many amps it is drawing. You can still check the connections and voltage at the terminals I stated to eliminate problems in the wiring harness circuit. I'm not an electrical guru, simply forced into diagnostics for same reasons as you.

[fireZ]

Thanks for the idea I will go at it again tonight

[JohnZ]

I tried to start my 68 Z today and the starter would not kick in and  turn engine. I pulled the starter and put cables on it and it worked good on the work bench. I put it back in the car turned the key and still just had a humm or buzz from under the hood.Any ideas? Thanks

The solenoid isn't pulling in - its fork extends the Bendix to the flywheel and engages the high-current contacts inside the solenoid that feed battery voltage to the armature.

Battery cables - condition? Contact areas clean and shiny at both ends of both cables?

Battery - Load test? What voltage do you read across the terminals?

[fireZ]

Can a solinoid be strong enough on the work bench to operate ok but once on the car to weak to pull into the flywheel?

[tom]

More likely the cables are corroded, frayed, loose, or otherwise damaged and not conducting enough power to the starter. Bad cables in the car would have no effect on bench testing the starter.

[Sauron327]

You've got to begin testing at the battery and proceed from there. And you are bench testing the starter and re-introducing it to an unverified system.

[fireZ]

I found the problem It was a brand new positive spring ring battery cable. I was playing with the positive and negative cables when my son turned the key and the engine turned over. The problem was a positive cable that was loose inside the spring ring terminal. I was able to wiggle the cable out of the terminal end with ease . Thanks for everyones help.