Bad starter? Or solenoid? 2007 peterbilt 379

Starter is heavy but an easy change. Make sure the big wires on the solenoid are clean and tight. I have seen an 1/8th of a nut turn make the difference. It's easy to see when it's dark out, have someone turn the key and watch for a little spark show at the battery/solenoid connection. That's one sign of a poor connection. You can see it in the daytime if you watch closely. You can also short across the two big posts on the solenoid with a screw driver you don't care about. Make sure the truck is out of gear first. If it turns then it's the solenoid, if it doesn't it's the started. Or you can be a little more civilized and use a DVOM and check the starter side of the solenoid for 12V with the key in start position.

Many new starters come with the big solenoid already attached. They also make starter rebuild kits if you are mechanically inclined, it's not hard. Most of the times it's just the brushes which is an easy change but replace everything in the kit. You can save hundreds that way.

 

I would suggest you also check the ground cables. Check the one from the starter to the frame rail. Also, check the frame to battery ground or grounds.
An amazing number of starting problems go away with clean grounds.

 

The "click' might be the 40 amp relay. Sounds familiar.

 

I've had very similar problem over the last year. First changed the starter and cylinode, then the button switch on dash, then another starter and cylinode, then battery cables, then the 40 amp relay on the firewall, then the flywheel. And now ready to put another starter in for the same problem coming back again.

I have found, I can turn the engine with a prybar just slightly and it engages great.
Is it possible, with the first strater replacement, got a 11 tooth when should've gotten 12 tooth or the other way around?
With each new starter, it seems great for couple months.

 

You've never had one of the bolts give you trouble I guess. If everything goes text book its an hour job, I would say from an hour to ????.

 

Just swapped out the relay on the firewall last week. Glad there was another relay right above it for fog lights that aren't there anymore. Cheap fix.

 

I added one of these to the "parts department" of the truck when I had to deal with it. I used a NAPA one.

 

I had a starter put on at the yard Monday, mine would sometimes do nothing when ya turned the key, and sometimes it would only click, you can to turn key to the right several to start it, this happening only every so often, sat morning in ft myers, fl , the starter gear hung up in flywheel, tapped on solenoid and it released, left it running til I delivered in Louisville Monday, total damges for starter and labor 415 dollars , also had a stter acle wheel seal replaced and popped new brakes on the front , 230 bucks parts and labor

 

Hold a screwdriver across the two solinoid nuts at the same time if it starts its a bad solinoid