This one has me wierded out.

A few months ago I started having problems with the starter on my 78 F250, 460, C6.

It's a positive engagement starter. The problem was that on occasion (with increasing incidence) the starter would not kick into the flywheel and would just spin, kind of an odd noise I can't describe in words.

These are known to be cranky with cabling issues but I ignored that and bought a new starter anyway. Installed the new on and had the same problem immediately.

So I did my homework (always best done "after" don't you agree?) and found out about the cable problem. So I replaced the battery positive and negative cables and also the main cable to the starter from the selenoid. Didn't help.

I had noticed that if you "snuck up" on making the contact with the key switch you could get the starter to work. This sneaking up on the contact was turning the key all the way to the right (yep nothing happened at all if you went all the way) and then let the key very slowly turn back to the left. Starter would engage and all was well.

So I changed out the ignition switch. The contacts were so worn and burned that I thought for sure that was the problem and sure enough I did't have any problems after that, until last week.

Damn thing is doing it again. Now it only does it in the morning when it's cold and then the rest of the day it's fine. Next morning, same thing. Seems to be getting worse though.

So, what's next, change out the harness? I'm not looking forward to doing that in the middle of the winter outside for sure.

Any suggestions?

(Note: This is the killer. NOW when this problem is happening I can sometimes get it to work right by sneaking up on the contact from the left. No kidding!)

 

Old battery may not be pushing enough amps anymore. I just went through a simmilar process. Starter would sometimes draw current, but not turn. I changed everything but the battery with intermittent results. Finally, swapped in a new battery, one rated with a hundred more cranking amps than stock just to be sure, and it works like a charm. Hooray for troubleshooting.

 

This is worth checking out but the battery is not that old which doesn't mean much I agree. However one morning while htis was happening my I cabled my neighbor's running 12 volt car to my truck's battery and it had zero effect.

Thanks for taking the time to respond to my question. :-)

 

Can you get it to crank consistently by jumping the contacts on the solonoid? That would at least isolate the problem to the ignition circuit or the solonoid/starter side.

Brad

 

Thanks Brad, tried this this morning, no change.

 

try the replacing the soliniod with one you know is good. Just had to replace it on my little ranger at wouldn't crank very fast like a dead battery even when jumping it put in a new soliniod and working like a champ even with the 6yr old battery back in it.

 

Changed that out new right after the first time this happened. I tried bypassing the solenoid altogether and same thing continues...............

 

Make sure you have good solid grounds between the block, cab, frame and fenders.
And one between the battery and the block helps too.
A bad ground can cause symptoms similar to a bad cable.

 

You mentioned something about replacing + and - cables, but is there a good ground connection to the motor from the Batt? I had a problem like that one time, amound the many problems i've had...

Alan

 

If there was no change when you directly jumped the solonoid terminals you either have a bad cable and/or connection, a failing battery, or a failing starter. By jumping the solonoid terminals you are taking the ignition circuit (keyswitch and wiring) completely out of the loop. Just guessing, but the Bendix drive is probably failing and/or full of crud. The Bendix is the part of the starter that kicks the shaft out to engage the flywheel. Bendix failure is a common issue, even more so on trucks that tend to get lots of mud, crud, and other assorted nastiness sloshed on and into the starter casing.

Your starter should be easily removeable unless you have headers or something else in the way. A few bolts and a couple of wires. Many shops will test it for free. You can get rebuilts pretty cheap, but if you intend to keep the truck I would consider at least going to a name-brand unit and not a store brand. If you intend to header up your truck at a later date, consider going with one of the aftermarket compact units that are designed to withstand the greater heat loading.

Brad

 

the aftermarket unit is a good idea or get one for a 92 or later (I believe that is right but in the 90s anyway) starter for a F350 with a 7.5L this is a gear reduction starter, and I know several guys running them on stroker big blocks running 12:1 comp and even higher and they work really good, and are considerably smaller than the old style so they clear headers better.

 

Thanks folks.

I haven't found the answer yet but a I'll let you know when I do. Its going down hill fast. I think in a couple more days it likely won't crank at all.

I'm next going to chase Brad and Monster's suggestions.

Here's exactly what I do know and what I've done so far:
- Starter is a rebuilt, installed just a few months ago. I don't think it was the starter then. May be now.
- It's a positive engagement starter so I can't change out an external bendix.
- The cabling from the battery terminalS is new all the way to the block and the starter.
- The ignition switch is new.
- The starter solenoid is new.
- When this problem started again I took the bat to starter cable off and put in a new bolt and some brass washers to make sure I had a good conection. I even added a good coating of Penetrox (contact anti corrosion and conducture material). Seemed to be betterfor a few days and then downhill again.

I'll check monster and see if a standard starter will fit this model.

Also going to try some new ground connections to other parts of the frame and see if that help. Heck I guess if I took a lead from the negative bat terminal to one of the starter mounting bolts that would tell me for sure if it was a ground problem. :-)

 

and o yeah :-)

I don't think there is anything swrong with the battery cause when I stuck a long 1/2 inch drive extension from the battery to the starter side terminal of the solenoid it welded it on there so good I almost couldn't break the connection.

 

I think the trouble now is that the new starter is bad.

 

There are 2 different diameter starter drives for Ford starters, most rebuiders use the smaller or 9 tooth drive some need the 10 tooth for proper engagement. Just something to check.
Have a good day -- Hotwrench