Some lessons learned recently about the starter on the M-25XP...
We've had a "slow" starter since we bought our boat last spring, but had always managed to start the engine until Christmas after a cold snap (O.K., cold by Florida standards!). Since I knew that the starter wasn't receiving sufficient amps, I decided to move the starting battery to the aft compartment under the bunk, right next to the muffler. This allowed me to use 32" 2 AWG battery cables. Additionally, a local mechanic suggested that I pull the starter and check it out.
This was the first time I actually "fixed" a starter, it's always been a matter of simply pulling the old one and replacing it. At first, I thought this might be less work, but then I found out what Universal wanted for a starter! Since I couldn't concieve of paying 700 bucks for a light-weight, TSO'd aircraft starter, I wasn't about to do that for a tractor engine in our boat! Now I'm sure that the starter could be obtained from a Kubota dealer or after-market at a much reduced price, but at the mechanic's insistance, I tore down the one I had and it turns out that a "rebuild" was a snap. It only took a couple of hours at a total cost of 1 sheet of fine grade sand paper and some grease!
Starter removal: Remove the alternator. Remove the wires from the starter solenoid. These are the wires on the post held by the nut and lock washer as well as small spade fitting from the igition switch. If your wire harness is stock, the wiring diagram in the Operator's Manual will have the color coding. No need to remove the bracket or the oil filter, as the two starter bolts can be accessed by a metric socket with an extension. Believe that the bolt heads were 13mm. Remove the two starter bolts and remove the starter.
Disassembly and cleaning. Start by removing the two small screws that hold the grease cap in place on the back of the starter. Once the cap is off, you can remove the slip ring that holds the shaft in place. The rest of the disassembly is simply a matter of unscrewing everything. Make a few notes, if required, so you can put everything back together when you're done. About the only non-obvious thing to do is pop the back end of the starter off (this is the end with the brushes and grease cap). You'll see a seam, and after you've got all of the fasteners off and the rest starter dissasembled (shaft removed, etc.), you can use a chisel or screw driver and a hammer to pop the end cap off. You can check the brush wear and replace if required.
Our engine has about 575 hours on it (not much for 16 years!), and the brushes were fine. There was a good bit of corrosion on the rotor and the plates. We used some Gunk engine cleaner to clean everything off and simply rinsed with water and let everything dry. After that it was simply a matter of removing any corrosion with fine grit (I used 600 grit) sandpaper. After cleaning, everthing was given a coat of Boeing T-9 and the bearings and gears were greased.
Reassembly. Fairly straight forward to reassemble in reverse order--the biggest challenge is to slip the brushes back over the rotor. Patience and a small screw driver will do the trick, although I'm positive some one has devised a better trick or tool for this! After reassembly, I recommend you find a 12v power supply and bench check the starter. It should run at very high speed, which will distribute the grease as well as giving you a warm fuzzy that the starter is in good shape.
To bench check, be sure the starter is secure (a vice works well), hook the ground up to the starter body, a positive lead to the positive stud on the solenoid, and then make a small jumper--touch the positive lead and the small spade terminal on the starter. It should spin like crazy!
Aside from sanding and allowing time for the water to dry, it took longer to type this than it did to rehab the starter.
Footnote: The problem was a combination of dirty/poor ground and a 40 FOOT (yup, feet) 4AWG starting circuit! When we bought the boat, I replaced the housebank with 4 6v batteries and added an AGM starting battery. I actually hired a marine electrician to do the work before I arrived to pick up the boat. AFter I moved the starting battery and removed the old wires, I was suprised to find out that he had used 10 feet of old 4AWG wire to ground the starting battery to the house bank, which was in turn grounded to the engine. I suspect that shortening the starter circuit would have fixed the problem without removing the starter, but now I'm satisfied that I won't have to deal with it for a while.
Cheers,
Mike
One trick to getting the brushes over the rotor is to push the brushes up against the spring and force the brushes into a cockeyed position that binds them in their little holders. Once you slide the armature/rotor assy in, you can give the brushes a little prod and they'll pop back into position. I was planning on some starter maintenance myself this winter but took care of our slow cranking problem by adding an additional run of #2 wire from the starting battery to the starter on its own switch. It's basically a permanently installed jumper cable and was the easiest solution I could come up with. I just about mounted a dedicated battery back in the cave under the bunk, but I always screw up fiberglass projects.
I had problems with the starter some years ago on our 1988 C34. The solution was to replace all the main cables with 00 cables. This is a job that can be done by the boat owner - I borrowed the heavy duty criping tool from the industrial electrical wholesaler who supplied the cables and terminals.
A hot engine room will cause higher current draw, which for us left us with a 'dead-stick' approach to a marina berth when the engine stalled as I put it into reverse. My wife needed no persuding about the need for the upgrade.
Looks like I'm next up to do a starter rebuild. After completing my alternator & electrical power upgrade, I was having what intermittent starter action. When I hit the "start" button, it either would
just "click" once, or
"click" multiple times, or
click and start to turn the motor and then stall, or
actually start the motor.[/list:u]
Since I'd just done a bunch of electrical work, I thought I'd goofed up wiring. But all was okay there. I cleaned all the terminal rings and posts. The starter worked fine. Put everything back together and the problem symptoms returned. Took stuff apart again and checked the connections. All was okay. Put it all back together and trouble returned.
Finally, I realized that maybe the problem was that the starter was just weak (getting old?) and tried the following test. With the alternator belt loose, activated the starter and it spun the motor easily. Tightened the belt, and starter wouldn't spin the motor. Loosened the belt and starter spun the motor easily. Then, while still spinning, I tentioned the alternator belt and the motor quit spinning. It seems the belt load was sufficient to stop the starter. FYI, the alternator controller waits 30 seconds after the motor starts before enabling the alternator. So I don't think the alternator itself was loading the belt and starter.
BTW, to make it easier to do all this, I hooked up a "parallel" starter switch. Very convenient to have while doing "single handed" repairs. (I'll post a picture of my handy dandy parallel starter motor switch just as soon as I can get the message board to give me the attachment and browse buttons. Strangely missing. Or I'll post it to the projects page.)
So I pulled the starter today and it's at home on my workbench now. Performed a "trial" disassembly and reassembly. I don't have the correct tool to get the ring clip off the shaft. So real repairs will have to wait. Also, if anyone has done this rebuild before, I have one question.
The field coils seem to be attached by very short wires from the middle section to the [brushes end] section. Do these wires detach somehow? It will make getting to the brushed tricky if I cannot detach the wires.
Got the starter disassembled and cleaned. Took lots of pictures during the reassembly process, so watch for a project page. Used 600 grit wet sandpaper to remove oxidation from the armature contacts and brushes.
Took the starter to Rose. Installed it and it "sort of" worked. It would engage and begin cranking fine. But about when it seemed the diesel was going to catch, the solenoid would slip and the gears would un-mesh and the starter would just spin at top bore. Happened several times. So I took it apart again while sitting at the companionway base. Then it wouldn't turn at all -- yes, I remembered to strap on a ground connection. Fiddled with it some more, pulled the solenoid out and double checked it's operation without the rest of the motor attached. Seemed okay so re-assembled everything and attached it to the diesel again.
This time the starter acted just like the pre-removal-and-rebuild starter. Solenoid kicked in nicely. But the electric motor just barely budged and then quit. And then I noticed that the fuel pump had stopped. I reached in to be sure I'd remembered to tighten all the connections and the fuel pump started again. Tried started the diesel and the exact same thing happened. But now I noticed that the battery cable lug was snug but the cable was wobbly. Wiggling the cable started and stopped the fuel pump.
[ During the week (while the message board was down), Ron Hill sent email asking if I'd soldered the cables. Since the cables were newly purchased and the connection from wire to lug was covered by heat shrink tubing, I assumed they were okay.]
Just as Ron suggested -- sort of. This cable was manufactured by Anchor and purchased from WM. But it didn't seem right that the cable should wiggle right at the connector. So I sliced off the heat shrink tubing over the wire/lug connection and the wire just dropped right out of the lug. Here's the kicker -- the wire end was solder coated and the lug appeared to have solder inside, but they just fell apart. The lug also showed NO sign of ever being crimped -- it was perfectly round. The other end showed clearly out-of-round shape for the crimp even though it was covered by the heat shrink.
So here's what I think. Lousy quality control at the mfgr. They failed to crimp the end and screwed up the solder job. All the errors were then covered over by the heat shrink tubing. If they tested it electrically, just the physical contact between the wire and lug made it look okay. When I installed the cable and bent the lug to match the perpendicular orientation of the starter motor stud, it must have pulled the wire right to the verge of "no contact" with the lug. When I tried to start the diesel, the vibration and slight lurch were enough to dislodge the cable and completely break the contact.
I repaired the cable and reinstalled it. Now the started works like a champ.
Lesson here: don't even trust new manufactured cables. Inspect them yourself.
Lesson here: when something that used to work just fine starts acting up after affiliated work was done, double check that work first!
Oh well, wisdom and experience can be expensive and / or time consuming.
Mark
Guy's : Solder all of your heavy duty and hi amperage connections, so you get the BEST electrical contact.
Just saying what I did back in 1990 and many times since!! :thumb: