Click no crank, truck won't start

[Matthew Jeschke]

Dang it. Was doing so well. New transmission, new engine, new steering system, ready to do transfer case.... Cranking system gave out.

Occasionally it will start but has gotten to point where almost every time Bendix goes out and won't crank. Worse now it blows 40 A ignition fuse.

I have a newer Bosch starter, tested at parts store and passes all checks.
Ignition will engage the Bendix gear.
Splines all good on gear & ring gear of pressure plate.
All connections to starter are solid and low impedance (static test).
Grounds are good on truck (static test).
No shorts to ground either.
New battery, tested and good (actually tested two separate batteries)


I'm wondering if my starter cable (battery positive to starter solenoid) is worn out? The ignition / relay seems fine since it clicks.

I don't see many tutorials on this so wonder if it's a common problem at all? I have 255,000 miles on the cable.

I do see people redoing the ground from battery to engine.

Also anybody tried these thermal breakers? It's a PITA when that $5 **** fuse blows

40A Thermal breaker

 

[Doubeleive]

do a voltage drop test on the starter cable
10.5v or less means it is no good, you will need a helper to turn the key to start.

 

[Doubeleive]

could also be the starter is working fine with no load, but not with a load

 

[MassHoe04]

If you are drawing more than 40A to result in blowing fuses, it sure sounds like there is a big short somewhere between the battery, the starter and the ground.
Maybe a loose brush inside the starter or something rattling around inside when under load?

While it bench tested OK, I would be thinking there is a chance that the issue is in that starter you have.

While a bad cable on battery or ground side would certainly prevent cranking, I think the fact that you are blowing fuses points to some kind of short.

 

[Matthew Jeschke]

Thanks @Doubeleive and @MassHoe04.

could also be the starter is working fine with no load, but not with a load

So as in a mechanical load? The bench tester at parts store didn't apply a mechanical load.

A short certainly crossed my mind. I do static continuity / voltage tests. They were all good. I also took starter off and tested again.

Unfortunately, I should have done more dynamic tests. I bought a power probe. Just touching probe (not pulling up or down w/ rocker button) seemed to eliminate the problem. I touched the probe to the body, which would actually indicate a bad ground?

I noticed the mounting surface of starter (to block) was dirty when I pulled it off. However, probing bolts and the bolt holes in block was good connectivity.

I guess I need to test some more stuff. Probably put starter back on.

Thermal breaker versus fuse?

Yeah, tired of blowing fuses. It's getting expensive to diagnose. Any idea if those thermal breakers work? I just don't want to pull too many amps and break something trying.

40A Thermal breaker

I wonder if I replace it regardless as "preventative maintenance", Although it's $75 I think this is the cable here?

AC Delco 2SX781B

Although multiple options for starter cable which is confusing. What is this??

Standard Motor Products A446L

 

[MassHoe04]

I was thinking maybe something worked loose inside the starter. If something is not anchored properly, it is possible the internals could shift when the Bendix engages the flywheel and cause things to touch that should be touching. Just a theory at this point. You said the starter was "new-er"... Doesn't mean something can't be wrong inside. My gut keeps hinting to me the issue is the starter. I can be wrong.

 

[Doubeleive]

fuse blowing I would think would indicate high resistance somewhere, have you done a ohm test on everything?

 

[Doubeleive]

see what the voltage is from battery ground to starter positive while the key is in start position. that is a drop test.
i would also test the ohm's from battery ground to starter

 

[Matthew Jeschke]

Yeah, I am with you both. I need to start wrenching. It's just a dreaded job haha Not a fun upgrade like my other stuff. Also I nearly deserve a Darwin award. Ran my hand through fan belt (motor running) on Sunday. Thank god nothing broke and I hadn't put on the fan yet but it's still swollen and no fun to wrench with.

I had worried the starter has a loose piece in it too... not sure if means anything but when removed, I can tip the starter and hear something moving inside. Guy at parts store recommended removing cover on the solenoid to see if anything is loose. I don't seem to have the fancy socket to get at the star head bolts though, it's like a reverse torque head.

All static tests look good. I need to put it back on truck as you mentioned and actually test ground load and positive load. Only problem is before I pulled it, it was blowing the fuse each time I turned ignition to run. I need to go to junkyard and get a bunch of those **** fuses. Otherwise they are $5 / each at parts store. I see I can order assorted batch off eBay but it only comes with 3 or 6 but about same cost as buying single at parts store.

Thanks for help! Sometimes more fun to just chat / post than fix haha

 

[Fless]

You might need a set of external torx bits. Very handy: