Hard cranking

odeek9 · Mar 22, 2018

Let's see if I can explain this properly. When starting the engine there is a 1 second pause then one groaning crank as if it's really struggling to turn over, then it might do it a second time and then it turns over perfectly and starts. The battery seems OK with proper voltage (though on the low side) plus I recently replaced the alternator. I don't know about the battery cable to the starter, or the starter. But once it cranks once, or twice all seems fine.
But today when I got back from the store and it had started normally there-this issue I'm trying explain is sporadic as there's always at least a slight pause for perhaps 1/2 second but then cranks fine. When it really struggles is only every 10 starts, or so. Anyway back to when I got home from the store I shut it off and had to re-start for some reason that doesn't matter it really, really fought to turn over. To such an extent that I thought it may not start-but it did.
A lot of explanation but did it do any good? Does it make any sense and, if so, what's the problem? Thanks!

RonD · Mar 22, 2018

Couple of things to check
Battery cables, both positive and negative

Clean the terminals and ends, while battery is disconnected, use a razor knife and slice battery cable's insulation back about 3"-4" from the end, then peel it back.
You are looking for a white residue, if found replace that cable it is bad.
Tape cable back up if it is clean.

Loosen and clean starter relay cables, and starter motor end of cable.
Loosen and clean Negative cable end at the engine.

Second possibility is starter motor's brushes, they are not conducting electricity to the rotor very well and need to heat up before they make good contact

odeek9 · Mar 22, 2018

Great! I've done some of that last year but not all of it and I didn't do a very thorough job. One question if you're still around: are the brushes replaceable? Thanks so much

RonD · Mar 23, 2018

Yes, you can rebuild almost any electric motor, that is why "rebuilt" starter motors and alternators are available.

You need to remove starter, and disassemble it, then see if you can clean up rotors contact surface and look at brushes and holders
Brushes wear down so wear out and get too short, these can be replaced with new so the spring in the holder can keep good pressure against rotor surface

odeek9 · Mar 23, 2018

Thanks for the help, Ron

tomw · Mar 24, 2018

A caution on 'rebuilding' starter motors. If you have to replace the brushes, you will likely have to have a LARGE soldering iron. The brush leads are soldered into the starter. Additionally, if you replace the brushes, you should also consider cleaning up the armature which required tools most of us do not have. The old instructions indicated that the armature must be chucked into a lathe, and the commutator coppers cut to a new finish, then the gaps between the individual pieces cleaned and deepened. There's a special tool to undercut the gap. I think some would use a saw blade as a generic substitute. You can get by by general cleanup, but success is not quite as good.
Alternators, on the other hand, are a lot simpler to repair. Generators, closer to starters.
The symptom described is generally called a 'dragging starter'. It can be caused by bad bearings in addition to the above causes. If it it a FoMoCo original with the 'built in' solenoid, the one with the 'bump', it is also possible the internal contact just needs cleaning. As the starter relay closes, it sends power to the starter, actually to the winding around the 'bump', pulling in a 'shoe' of metal like a larger solenoid, that in turn closes some large contacts internal to the starter so when the shoe hits home, it has pulled/pushed the starter Bendix gear into contact with the ring gear, and viola, power to the rest of the starter is provided. The starter relay sends power, but the actual motor gets powered when the starter has engaged. If you get nuttin' , it could be that internal contact needs cleaning and burnishing.
You can inspect the contact, I think, by removing the bump cover. Move the shoe by hand and you'll see where it interacts with the contact.
tom

odeek9 · Mar 24, 2018

Hey Tom-thanks for the info. You just saved me a headache as I'm not about to go through all of that. I thought that it would just be a matter of sliding the bushings in. If I get to the point where it looks like the starter is the issue then I'll just buy one.
Alan

Hard cranking

odeek9

Member

RonD

Official TRS AI

odeek9

Member

RonD

Official TRS AI

odeek9

Member

tomw

Well-Known Member

odeek9

Member

Sponsored Ad

Sponsored Ad

Staff online

Members online

Member & Vendor Upgrades

Latest posts

Truck of The Month

Recently Featured

Follow TRS On Instagram

Latest Album Photos

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals