Engine not starting, Ideas please

[Streff]

After much research and input, I upgraded the Alternator today from the original 51Amp to a 95Amp. This is on a 3208 CAT 1990 engine. All connections seem to go well but the engine won’t start. It won’t even turn over.

The only thing that was a bit unusual, maybe related, had to do with the starter. The ground post of the old alternator was connected to the starter with 2 cables, a black neg. and a green ground wire.

When I came to remove the cables from the started, the starter post seems to rotate when unscrewing and screwing the 3/4” nut that holds all cables. I am not sure if the post disengaged?? The starter is getting 12.8volts.

Is there an engine fuse besides the engine breaker in the panel, that I am missing?.. I am thinking of opening up the starter to see if it’s post was dislodged or such. I am at a loss right now..

Any ideas or input would be much appreciated.

Thank you

Streff

 

[SteveK]

A starter has a negative post or uses connection to engine as ground. It has a positive (live) cable. Then it has a smaller wire from the start button/switch which is a relay to connect/close the live heavy positive cable inside the starter.
You can jump this terminal to eliminate the start button/switch. Yes there would be a fuse on this start line so jumping will tell you if you have blown a fuse.
The ground post of the old alternator was connected to the starter with 2 cables, a black neg. and a green ground wire.
Interesting, you had two cables from a ground post on alternator go to one post on the starter.

 

[The Brockerts]

Streff,
I've got 3208's Cat 1990 engines also, 2 of them, original setup. Post a picture of your setup and I'll post a picture tomorrow of mine to see if they are similar and take some readings. Jumping the start button usually throws a large spark and will melt a screwdriver, but will turn things over.
The Brockerts

 

[ghost]

Does the solenoid produce a loud click when you turn the key?

There is often a relay just before the solenoid, that’s a likely culprit. If the solenoid is not clicking, do a web search and teach yourself how to trigger the solenoid (short jumper from the big starter positive lug to the smaller solenoid lug. With the key on, your engine should start right up when you do this. All assuming the small relay has gone bad.


But before you do any of that, make sure you’re in neutral.

 

[RT Firefly]

Greetings,
Mr. S. ANY starter I've ever seen has a nut on the positive starter post (bolt). This is never to be loosened or taken off (should be tight at all times). It anchors the starter post to the starter and keeps the post from rotating when removing the other (outer) nut that secures the cable(s).


Similar double nut set up on the solenoid, IF I recall correctly.

 

[Ski in NC]

The cable lugs on the starter should not rotate when loosening the cable nuts. If they do, you want to snug the locking nut. If the stud rotated, something may have broken inside. Or there may be some other wiring issue. Easy to troubleshoot with a voltmeter and a helper.

 

[oscar]

Do you have a multi meter? You can get one for $25, complete with instructions.