How To: Rebuild your starter

[justgary]

So some friends and I were out on the water Thursday morning having a great time. We had stopped the engine about ten times, and it cranked just fine until my buddy turned the key and got, "click." Uh-oh. I banged on the starter with a wrench, but still it just clicked.

I'll make the long story short by explaining that my wife was able to meet us as a nearby boat ramp and jump start the engine so we could drive the boat back to the ramp where we left the trailer. It all worked out OK with only an extra hour lost, and now I need a new battery. I have never had a battery just quit like that, so I decided I had better check out the starter to make sure that it wasn't the problem.

What follows is a photo journal on how to disassemble, check, and reassemble your GM 5.7L starter. If the mods would like to make this into a how-to article in the resources section, I'm on board.

Step 1. Remove the battery ground wire from the engine.

Step 2. Remove the positive battery wire from the starter. Next, remove the start wire from the small lug on the starter solenoid.

Step 3. Use a 9/16" wrench to remove the two bolts under the starter. The bolts are knurled to keep them from turning freely, so you have to wrench them the whole way.

Step 4. Once you get both bolts out, the starter should be in your hands. Take a minute to inspect the ring gear on the engine to make sure you don't have damage or a bunch of crud inside.

Step 5. Start at the flat end of the starter, and remove the two small screws that go through the cover. Mine used an E-6 drive, but a 3/16" socket will work if you have one. Next, remove the two long threaded studs.

Step 6. At this point, you can remove the end cap covering the brushes. Use a 1/2" wrench to remove the nut holding the short wire going from the solenoid to the brush plate. Lift the brush plate off the starter.

Step 7. Pull the magnet case and armature from the front of the starter. Pull the armature out of the magnet case. I found a bunch of rust chips stuck between the two parts, which no doubt added greatly to the drag (and hence current) in the starter.

Step 8. By now, you have seen the planetary gears that are responsible for multiplying the torque your starter creates. Remove the planet gears by simply lifting them off of their spindles.

Step 9. Use an E-5 driver to remove the three screws that hold the solenoid to the starter housing. I had to go buy a set of drivers because I didn't have an E-5 size, and even after that, I had to grind the side of the driver to let it slip past the housing pocket. Remove the solenoid by jiggling it over the forks inside the housing. Remove the rubber dust cover between the solenoid and the sun gear.

Step 10. I had to make a tool that looks a lot like a paint lid remover to allow me to grab behind the sun gear casting and pull while I used a screwdriver to pry up from the solenoid side. I had the housing in a vise for this step, so not every step happened in my driveway. I used a short piece of drill rod to make the tool, but a paint lid lifter just might work. I didn't bother hardening the tool, I just pounded it out on the back of the vise in about three minutes.

Step 11. Once you have the sun gear moving, simply pull it out. It will bring the bendix with it. Be aware that the end of the shaft has a thrust washer at the pointy end of the starter housing, so don't lose it.

Step 12. Clean the parts in your favorite solvent. Inspect everything for cracks or other issues, including the armature windings to make sure nothing is shorted. Check the brushes to make sure that they still have sufficient length to work without rotating out of their holders. They should move smoothly in their holders, and the springs should have plenty of force all the way along the brush travel. My starter had obviously gotten wet at some point (it wasn't me), but it is the original one in my boat. The shaft was a little pitted where it had water on it in the needle bearings at the pointy end, but I decided to just let it be.

Step 13. Dress the commutator with very fine sandpaper. It should be smooth, and it should not have any grooves. Next, check the commutator to make sure that the gaps between the poles are deep enough to insulate the poles from each other. Over time, carbon dust from the brushes fills the gaps, causing the poles to short together, increasing current and decreasing torque. If you need to cut the gaps deeper, grind the end of a hacksaw blade to the proper thickness and use it to saw the gaps until they are deep enough.

Step 14. It is now time to reassemble the starter. Grease the needle bearing, the bushing in the end cap, and between the sun gear and planet gear plate. Next, grease the planet gears and inside the sun gear. Finally, put a dab of grease on the yoke and forks of the solenoid lever. Insert the bendix, lever, and sun gear combination into the housing, and remember to put the thrust washer on the shaft. You may have to tap the sun gear to get it to seat in the housing. Place the planet gears on their shafts.

Step 15. Reinstall the rubber dust cover and the solenoid, making sure to get the button on the solenoid behind the forks of the lever. Slide the armature into the magnet ring (it will snap quickly under magnetic force), but pay attention to the magnet ring. It will only fit one way on the housing, so look for the wide and narrow sets of tabs at the ends, and put the wide pair nearest the planet gears. Stack the two on to the housing.

Step 16. Now comes the tricky part. Find a spare 3/4" PVC pipe coupler and work the brushes onto it. Basically, compress one brush and then put the PVC piece up through the hole in the bottom of the brush plate. Hold the brush with the piece, then compress a second brush. Continue this process (and it may take several tries) until all four brushes are on the PVC piece.

Step 17. Push the brush plate down onto the commutator by aligning the PVC piece with the end of the commutator shaft. The brushes should easily transition from the PVC to the commutator. Rotate the brush plate until the wire aligns with the stud on the solenoid, and mount the wire on the stud with the 1/2" nut.

Step 18. Put the cover on the end of the starter, and reinstall the two small screws through the end cap and into the brush plate. Reinstall the two long studs and secure them.

Step 19. Test the starter by using jumper cables to connect battery minus to the starter case, and battery plus to the stud at the outside edge of the solenoid. Put your foot on the starter (it will try to jump from the torque) and use a screwdriver to make contact from the battery plus stud to the smaller start wire stud. Check to make sure that the bendix throws fully against the thrust washer and that the starter spins freely. When you remove the screwdriver, the starter should stop spinning, and the bendix should fully retract.

Step 20. Lightly grease the bendix before reinstalling the starter. In a harsh environment, consider using some aviation shellac on the threads of the studs so they will come out next time. Reconnect the start wire, the battery plus, and the ground strap. At this point, you should once again have a working starter.

Happy boating!

[bunji169]

Great write up. You lost me at the disassembly though. I think i'd just get a new GM 5.7 starter at Autozone for $100 and call it a day. Looks pretty easy to swap out in your pics. I'm just to lazy to go through all that trouble taking it apart, soaking it in cleaner, lubing and re-assembling. I'd probably make it worse...If I ever did decide to rebuild one, I know where to go for step by step pics.

[GreenMan]

Excellent info sharing, Gary!

[Slayer]

Well done! Thanks, Gary.

[Wayne]

I would make one change to your write up. "Clean using your favorite solvent". There is a coating on the windings and some solvents can dissolve it causing a short if the starter is put into use. Ask me how I know this ?. Only the windings needs this precaution.

Otherwise great write up.

[BFresh]

Nice write-up! Just curios, as was mentioned, what symptoms would make you decide to pull your starter and rebuild it versus buying a new one? Maybe check the planetary gears out first inside and just do a rebuild unless they are messed up?

[skiatook_bu]

My starter locked up maybe 8 years ago. I wanted to get back on the water and not wait to get one shipped in, so I pulled it, cleaned it out, used some naval jelly on some rust spots, put it back together and it is still working to this day. Cost was $0 because I already had the stuff on hand. Great write-up. I just winged it.

[justgary]

The number one reason that starters quit is that the brushes wear down and the loose carbon packs the commutator grooves. On a boat, the second reason is probably rust between the magnets and the armature.

In my case, it's a 1999 starter. The battery apparently just died from one start to the next. No sense changing the battery if the starter was partly to blame. No sense changing the starter if it doesn't have anything wrong.

[justgary]

And it makes sense to me to save money where I can. If I take it apart and discover something broken, I can always put it back together and go buy a new one.

[09vRide]

Great post. Thanks for putting it together.

[drh]

@justgary Thank you for writing this up. Just did this last night after you linked it in another topic yesterday. My starter is occasionally sluggish and I've ruled out battery and connections. It did it pretty bad this week a few times on the water, almost wouldn't start...and then other times less than an hour later it cranked liked normal.

When I got in there it was the same story as yours - rust on the armature and slight carbon on the commutator. Also I noticed small surface cracks in the insulation on the windings of the armature. Nothing that looked deep enough to cause a short though. Could this be my problem?

BTW a deep well socket works for reseating the brushes if you don't have a PVC coupling.

[justgary]

9 hours ago, drh said:

@justgary Thank you for writing this up. Just did this last night after you linked it in another topic yesterday. My starter is occasionally sluggish and I've ruled out battery and connections. It did it pretty bad this week a few times on the water, almost wouldn't start...and then other times less than an hour later it cranked liked normal.

When I got in there it was the same story as yours - rust on the armature and slight carbon on the commutator. Also I noticed small surface cracks in the insulation on the windings of the armature. Nothing that looked deep enough to cause a short though. Could this be my problem?

BTW a deep well socket works for reseating the brushes if you don't have a PVC coupling.

I don't think small cracks are going to make any difference.  If the wires short together, you'll probably know.  The big thing is getting the gaps in the commutator clean and deep enough.

Good call on the deep well socket.

Does yours work better now?

[drh]

@justgary Initial test when I put it back in the boat was good...seemed strong and fast. It was an intermittent problem so I guess time will tell if it's better.

It was interesting that when I bench tested it before reinstalling the starter would not disengage - just kept spinning. I had to energize only the solenoid a few times to get it retracting correctly. Then it worked fine. I didn't remove the solenoid or anything on the drive end of the starter so not sure what went wrong there.

[justgary]

5 hours ago, drh said:

@justgary Initial test when I put it back in the boat was good...seemed strong and fast. It was an intermittent problem so I guess time will tell if it's better.

It was interesting that when I bench tested it before reinstalling the starter would not disengage - just kept spinning. I had to energize only the solenoid a few times to get it retracting correctly. Then it worked fine. I didn't remove the solenoid or anything on the drive end of the starter so not sure what went wrong there.

The ring gear should help kick the bendix out when the motor starts.  Perhaps the solenoid spring is a little weak, or maybe a bit of oil would help.  If it works OK, leave it alone.

[drh]

Circling back to this, one month after the rebuild my intermittent slow start problem is gone. Boat starts faster than ever, consistently. This project is worth tackling - even if you only get to step 8 which is as far as I went.