I posted a while back on this issue. I am with the opinion that the starter may have an issue. I am testing out around 850A draw to the starter during start mode. Batteries start at 12.5V and pull down to 10.0V. I have not been able to test the voltage at the starter during start mode. That should confirm bad cabling if there is a high amount of working resistance in the cables.



I was just curious what the heck goes TU in the starter to create such a high draw? Per posts here, 850A is off the charts?? I would sure think that would nearly confirm the cabling is probably fine as that is plenty of power headed to the starter. Again, voltage drop test at starter should confirm.


Even at a locked rotor state, the starter should never pull this pull? Can I brush it or is this internal in the rotor portion of the starter? I would sure think something is shorted big time in there.

my starter's in very good condition and it pulls ~300-400 amps per a Vat-40 test and the truck spins over really quick on top of that.

Sounds to me like you need at least brushes in your starter.

I'd replace those and clean the armature contacts where the brushes rub, grease the bushing in the nose cone and the back plate so the armature can spin easier, and make sure there's no shorts in the windings. You may want to get a new solenoid as well.

All the starter is is two magnetic fields(one on the case either by field coils or permanent magnets) and one on the armature. the like magnetic fields push away from eachother and that's what turns the armature.

my starter's in good condition it pulls ~300-400 and the truck spins over really quick.

Sounds to me like you need at least brushes in your starter.

I'd replace those and clean the armature contacts where the brushes rub, grease the bushings for the armature, and make sure there's no shorts in the windings. You may want to get a new solenoid as well.

that's really all there is to rebuilding a starter.



Thing is, I cannot see how replacing brushes will fix this problem. Usually, the started does not pull much juice, and turns over slow when they are toast. I inspected the starter last year and all "looked" good. I did no testing on it.

850 is off the charts. daves right, rebuilding them is easy assuming nothing breaks. finding the rebuild kit is the hard part, i was unable to find one. i think LMC truck sells them...

when mine failed, hi draw no spin. the brushes had failed mechanically(one came unhooked at the screw, this lead to others melting down) and wiped out the commutator with them. this was not a rebuildable starter.

Thing is, I cannot see how replacing brushes will fix this problem. Usually, the started does not pull much juice, and turns over slow when they are toast. I inspected the starter last year and all "looked" good. I did no testing on it.

the brushes could just be worn down. when an electric motor's brushes(in one that have them) go bad the motor spins up slow and takes longer to get to full speed. I"ll PM you an example of a motor with bad brushes.

94, 300k miles, you probably need a new one. It is not terribly expensive.

Just my 2cents. Make sure you install it correctly.

Just my 2cents. Make sure you install it correctly.



What does that mean? had the starter on and off about 5 times now.




Just a revision of my test. V drop is 1V through the cabling going to the starter. key off, 13.0V, key on with glows, 12.1V, recover to 12.5V, start mode at bat, 10.2V, start mode at starter terminal 9.2V. Amp test, 1st try, 635A, 2nd 765A. I have to use inrush on my meter by myself that only traps the first 100ms. Probably higher than I got.


All in all, cables seem fine. Those cables are probably only 2ga which will have drop when trying to carry 800A. I will get the starter out and hopefully get this taken care of. I was reluctant because we just welded a stud in the block to hold the starter so it is now more of a beeotch to get out.

why did you weld a stud in the block?

why did you weld a stud in the block?


Block was broke when I bought it. some JA tried to put JB weld on it. I already drilled deeper in the block and tapped it but did not hold too long. Cast iron can be difficult to get a high performance thread in. That bold started coming loose again so I welded a grade 8 stud in there. She is in for the only haul now!


Mount surface plane was unaffected. Just the far outside bolt had broke out the threaded hole.

Sounds like getting that starter off will be tough. Because most of my starters are a PITA to Re and Re , I"ll always IRAN it.(inspect,repair as necessary) while it's out, then give it a quick bench test run just to check for proper operation. Always secure the starter well or it may fly across the shop. This won't guarantee that the starter is perfect, but it has saved me from putting a problem starter back in a couple of times, even when there had been no starting problems before the starter came out. If you have a problem and aren't sure what to do, there is usually an electrical shop nearby that can test your starter for a reasonable price. A burned contact in the solenoid can give you high draw and slow turnover as well as the brushes and bushings as Dave mentioned

Problemo el solved a le


Starter was shit. Happened to have another in the shop from a friend that was identical but not as pretty. Apparently, it is the inside that counts. :)

I pulled the other starter apart before install of the replacement because wanted confirmation it was bad since this job is such a pain. Two brushes were hung up (no contact), the other two were over worked and one had actually nuked the wire off if it. Things did not smell right in there though I am pretty confident a good cleaning and a brush pack would put it back in service.

I load tested once again with my inrush function and got 750A. Keep in mind though that this traps 100ms of draw. It is designed to capture peak amperage for motor starts. I would bet if I had an extra hand to turn the truck, amperage would calm down. Truck rolls over perfect now.

Thanks guys.

told ya the brushes would be burned apart...and that armature is likely fried from overcurrent...mine was

told ya the brushes would be burned apart...and that armature is likely fried from overcurrent...mine was

crispy starter anyone? :p:

no one mentioned the nose bracket. If you don't have one, that would explain the broken starter bolt. If you don't want further issue, you'll need to find one.

Nose or tail bracket has been on since I have owned it. It was broke when I got it though. I could not get the bolt through it this evening so I will have to run in a few days like this but I know to get it back on. The be honest, I doubt I will have further issues now that the troubled area has been beefed up and normalized and running an over sized grade 8 stud.


I feel like a tool for not looking at the brushes last time it was off. I am a CNC owner/machinest, etc. I should have know better. I honestly could probably salvage the starter as is and I would bet my left nut on it or 100 bucks if anyone wants to take it. I inspected the insulation and though it was obviously hot, the fingernail test concluded that the laquer coating was not hurt. I could probably give those brushes a tune up and re terminate that one and make it go if need be but man was I glad to just have one sitting on the shelf.

The irony of it all, as I thought about it today, is I have two trucks. One does not start and one does not stop (needs a master cylinder). Made my day:)

And if you end up needing a new starter, don't buy one from AUTOZONE or ADVANCE. I learned my lesson about those the hard way. Bought one because they had it and I didn't want to wait for one from the dealer. Went through 5 of them in 6 months. Everytime they tested it in the store and said it was good, yet it wouldn't spin the engine over fast enough to start it. The last time they tested it there machine said it was good, but yet it took almost 5 seconds for it to spin up and it popped there machine from current draw. After fighting with them for 20 minutes I got my money back. Personally I would reccomend a POWERMASTER if you need one in the future.