Sanity check: My starter is bad, right?

'93 F150, 4.9L, auto

Turn key, loud click.  Jump pack, loud click.  Battery tender for two nights, light shows green, loud click.  Clean terminals on battery, brush, retighten terminals, battery tender again, loud click.  Direct jump solenoid on fender, loud click.  

Bang on starter with hammer, instant start.  

Don't berkeley with it because its too unreliable to take it to work in the morning, resolve to berkeley with it tonight in order to be productive this weekend.  Get home, disconnect battery tender, loud click (expected this time.) 
Bang on starter with hammer, get a couple revolutions.  Bang on starter a few more times, get nothing but loud click.

Maybe I need to tighten the cables at the starter?  

Once, with an aluminum bellhousing, I had corrosion get in there and prevent a good connection.

Check ground and then replace starter cause that sounds like starter. 

Cables could be rotten inside the jacket or where they meet the terminal. 

I replaced a battery cable in a Wisconsin V4 last week because the cable was crumbling inside every time you flexed it 

In reply to ShawnG :

Cables are.... 15 years old, and have been in inland-Florida for all of that time.  I'd think not?  Maybe though?

Sounds like brushes in the starter. Bout 95% sure , based on the diagnostic descriptions from a decent car guy!!!

starter system diagnostic class 202 :

Grab you favorite 12v DC meter (analog is actually best for this, but anything'll do. Even a test light. )

Put the positive lead directly to + terminal of the battery. Put the negative lead directly to the - terminal of the battery. 
While watching the meter, have your trusted accomplice attempt to start the vehicle. If the voltage drops just a little (maybe as much as 9VDC, maybe only 11) the battery is good, has a charge and is not the culprit. If the Voltage Drop is VERY large (2-3VDC or less) then it's the battery (pro tip: might be bad battery, drained for various reasons, or bad alternator not charging it)
Now, the tricky part: move ONLY the positive lead to the clamp on the + terminal. Watch while help tries to start. 
If the voltage drop is the same minor drop as before, that connection is now proven good. 
If, however, there is a lot of voltage drop, you have now found the loose connection. Check each "joint" is the positive and the negative parts of the entire high current side of the starting circuit to prove each one is a good connection. 

Bit long winded, but my dad taught me that when I was a wee lad, knee high to a grasshopper. 
The Electrical Theory is that the low current draw of the meter, as well as minor systems on when not in start mode, will pass enough Voltage through, to read full battery voltage (13.8 nominal)

The several hundred Amps the starter draws, for several seconds, will not pass through a bad connection, and that is where the problem is. 
If you get all the way to the ground on the starter case, and the positive stud of the large wire on the starter, without finding the massive voltage drop, then it's obviously the starter. 
On GM (and any starter with the Solenoid - fancy word for relay - mounted on the starter where it can heat soak, like newer fords, for some reason) then ya gotta determine what part of the starter has failed. 
Since your truck has the solenoid on the inner fender (where it belongs ) hitting the starter with a hammer , making it work, tells us that it's the carbon brushes sticking to the armature, glazed, or worn out carbon brushes/springs. 
Your truck has a starter that can be fixed by a shade tree mechanic... but parts might not be available, expensive, and by the time it has enough wear for this, it probably has other wear, so the cost of a starter becomes a value. 
Today, along with troubleshooting, we learned why SBC drag racers would sometimes use a (gasp!) Ford style Solenoid, to prevent heat soak non start problems, with the Chevy design. 

Trust me; all that is WAY easier to DO, than it is to explain with my writing! Much easier than it sounds. 
Many battery's, starters and alternators have benn changed out, only to find one of the others, or a loose/corroded/bad connection, was the actual fault. 

Newer systems get a bit more complicated, but that '90s truck shares a ton of tech with its F1 (or 2, 3, etc) ancestors, and before!

In reply to ShawnG :

I've seen the powder the copper corrodes into inside the vinyl sheathing a few time. Father Time and Morher Nature do like things to return to there separate elements, despite us trying to stop it 

Most specifically the starter's brushes are bad, so you may want to get it rebuilt so you'll have another good starter.

When I was a young, broke apprentoid, I bought a new battery because my starter was just going "click" in my IHC Scout.

The starter was new and couldn't possibly be the problem so the battery must be it, right?

New battery - "click"

Man, was I angry.

Hit it again and "click" but it was dark so I saw the spark coming out of where the terminal meets the cable.

My instructors story about always checking the cables and connections came flooding back.

I'd wasted about half of my two-weeks pay on a starter and battery that were unnecessary because I didn't do a proper diagnostic. 

A $25 cable would have fixed it and I wouldn't have been eating ramen for a week.

I always check everything now, I've seen a ton of weird electrical issues be solved by remembering the words "clean, dry, tight".

Your issue sounds like every dirty / faulty battery terminal or cable lug that I've ever fixed.

Usually the connection is just good enough to fire the solenoid or turn the starter a bit but then the current draw burns out whatever minor connection was being made and you get nothing. 

Wiggling and banging stuff restores the poor connection just enough to start the process again. 

ShawnG said:

I always check everything now, I've seen a ton of weird electrical issues be solved by remembering the words "clean, dry, tight".

Very good words to live by!

Your issue sounds like every dirty / faulty battery terminal or cable lug that I've ever fixed.

The part about the application of steel on a wooden handle, against the starter,wouldn't fix a loose / corroded connection, though. 
That's why, I lean towards the connection at the armature/brushes. 
But easy enough (albeit time consuming, and needing help) and foolproof way to check. 

ShawnG said:

Usually the connection is just good enough to fire the solenoid or turn the starter a bit but then the current draw burns out whatever minor connection was being made and you get nothing. 

Wiggling and banging stuff restores the poor connection just enough to start the process again. 

Yep. Ive probably used that method as much as the proper electrical troubleshooting with a meter, due to not having a meter handy, or too lazy to walk over to get one 

Low tech solution do have their uses. 

Terminals were loose at the starter.  They are bronze, so I was probably hesitant to really torque em when I did my engine swap and they worked their way loose enough to have corrosion. 

Later I'll get under there, take the wires off, brush em, then put everything back together. For now it starts and I gotta go do truck stuff.

I've added a dedicated ground wire from the battery to the starter ear bolt on both my Fords, it does help. On the E350 I even added a second hot lead to the starter; the stock cables are really tiny.

I expect it's a combination of the brushes and terminals, if it were terminals alone I doubt the hammering would help, fixing the terminals probably just let enough power get to the starter to fire it up through the worn brushes.

Can you get to the positive terminal on the starter?  Sorry, you don't even need to do that.   Put truck in park auto trans, put in neutral manual trans.  Set parking brake.  Hook a jumper cable to the cold side of the solenoid and touch the other end of jumper cable to the positive side of the battery.  Starter should engage and spin.  Does not engage and spin?  Take the starter off and test it on the ground with your set of jumper cables.

Using both jumper cables, positive to positive terminal on battery, positive to positive on starter.  Negative to negative on battery and hold the starter in place firmly with your foot and touch the negative cable to the body or ear of the starter.  Careful!  If the Bendix engages and the starter spins up it will scare you if you are not ready as the starter tries to twist out from under your foot like a trapped wild animal.

Or if you have it off, take it to Advance-O'reilly-Zone to have it tested.  Or if you have something better like *NAPA, take it there.  That way you can see if you have a high current draw.

*At least I hope NAPA is better.

Mr_Asa said:

Terminals were loose at the starter.  

I gotta go do truck stuff.

nice $0.00 fix

Please stop hitting permanent magnet starters with a hammer...

In reply to AngryCorvair (Forum Supporter) :

Been a while since I've had one of those.  Planning on savoring it for a while

In reply to Mr_Asa :

I raise a glass in your general direction!

In reply to ShawnG :

Actually, I was using a hatchet.