Starter won't disengage!

[beebopbogo]

The engine has been working great for about 8 months but I decided to change the fuel filters in preparation for a big trip. Unfortunately, during the bleeding process my starter started smoking slightly so I immediately stopped the process. After about 10 minutes I tried the starter again bit it wouldn't disengage even after removing pressure from the start button. I shut off the battery to stop the starter. I figured it had to do with overheating, so I removed it, brought it to the shop where they refurbished it. They installed a stronger return spring, soldered some of the internals and smoothed out two flat spots to bring it back to round. It then tested perfectly on the test bench.

After reinstalling, same problem.

I removed all wiring except the power wire from the battery and the ground wire from the engine lug to the negative terminal on the start battery. Jumping the heavy solenoid terminals spins the starter without engaging as expected. Jumping the S terminal to the power terminal on the solenoid cranks the engine over as expected but doesn't disengage after removing the jump (I was using a heavy wrench).

The shop suggested rough flywheel teeth so I again removed the starter and felt the flywheel teeth. The teeth had tiny burrs I could feel with the tip of my finger, way less than a millimeter. I used a file to grind all the teeth smooth using a magnet to catch the small amount of filings until all the teeth were smooth to the touch (3 hours of back breaking work. I have blisters on the top of my get from kneeling so long, hehe). After reinstalling, still no change.

Someone suggested slightly loosening the 3 bolts holding the starter on to maybe help release the starter gear from the flywheel. I did so, activated the starter, it wouldn't disengage, so I jiggled the starter, but no go.

Every test, I adhered to the 15 sec on, 5 min off limitations to prevent overheating the starter. Learned my lesson on that first bleed! 30 seconds fried the starter.

What could prevent the starter from disengaging???
1) Solenoid? No. I remove power from the solenoid but it keeps cranking.
2) Friction at the flywheel? Seems all right. The starter folks painted the teeth black and said the wear looked normal when I brought it back after testing on the boat.
3) Electrical issue? I can't see how that could cause this problem.
4) Starter alignment? It works great with the current shim for over 2 years until now.
5) Starter itself? Works perfectly on the test bench.

What's next? New engine?

[model 10]

There is no voodoo here. If the engine starts and the starter does not disengage it is either the solenoid or the drive or the switch. If the engine does not start and the starter keeps running, it is either the solenoid or the switch. The drive only disengages after the engine starts and the engine turns faster than the starter motor. Given the nature of the drive design, it is unlikely for it to stick engaged but to not engage or slip is a more likely problem.

[DeepFrz]

New solenoid. Or taking your solenoid apart and cleaning it might work.

[beebopbogo]

The solenoid is brand new and works perfectly on the test bench.

I completely bypassed the switch (removed all the wires even) and simply used a wrench to make the connection between power and the small solenoid terminal.

Before this issue I would push the start button and the starter would engage. But I could also tap the starter and crank the engine for less than a second. Now I tap the start button and it cranks until I turn the battery off. But only when attached to the engine! When removed from the engine, the starter/solenoid act normally.

I say again, it only acts abnormally when attached to the engine. That has got to be an important clue...

[model 10]

The switch.

[jongleur]

When you short to get power to the starter, then
turn off the battery to stop the starter, can you
then unshort it and turn on the battery without it
trying to start?

edit: My guess is bad solenoid.

[beebopbogo]

Yep.

I short the contacts and pull away within 1/2 second.
The starter runs on its own.
I turn off the battery switch to stop it.
I can immediately turn it back on within 1 second and there's no starter activation.

[nimblemotors]

I had this problem on a Rx7. Starter works fine on the bench, but would not stop turning when in the car. I never fixed it, so have no conclusive fix.
I suspected the alignment of the gears so it would not pull back from the flywheel, that is the only thing that makes sense to me, there is a bushing
for the shaft that could be worn out.

[jongleur]

"bushing for the shaft that could be worn out"...that ever so
slightly changes the angle of the shaft when engaged.

Yeah, that's my new guess.

[Viking Sailor]

Hi,

This post has nothing to do with you starter problem.

Make sure that you are not getting exhaust cooling water into the engine via the exhaust values. Your raw water intake through hull should be closed and the water pump">raw water pump impeller should be removed when doing prolonged engine cranking.

You should check your engine oil to make sure that no water has gotten into it.

Best of luck,

Paul

[SimonV]

I would say it's the solenoid if it is open able there will be a washer that makes the contact bet it's deformed or damaged by arking. File and clean or just replace the unit. And yes make sure the water intake is off.

Sent from my GT-N7105T using Cruisers Sailing Forum mobile app

[jimbunyard]

In 7 above, are you still in test mode with just main power cable? If in test mode, the solenoid is getting juice from somewhere, indicating some kind of short in either the starter, the solenoid or both. If hooked up normally, then it sounds more like the ignition switch.

In 4 above, you say that before the current issue you could 'tap the starter and could crank the engine for less than a second'. Do you mean that you could physically tap the starter (like with a hammer or wrench) and the starter would turn? If so, then that seems like there is some preexisting electrical issue in either the starter/solenoid or boat wiring.

Hope you were being facetious about new engine....

[beebopbogo]

Checking the solenoid is easiest at this point. I'll try that again.

But it can't be an electrical issue. The gears on the flywheel and starter remain attached which keeps the Bendix from springing back which keeps the solenoid's contacts shoved closed (the small starter gear and the solenoid's "jumper bar" are connected on a lever). So the only way to free the gear is to remove the power from the battery. I'm assuming this unloads the starter's gear enough to allow it to spring back, disconnecting the internal jumper at the same time through the activation of the lever.

When I say I "tap the starter," I mean to say I could quickly push in and release the starter button which would start and then stop the starter. In other words, it would not stay on. This was a week ago when everything was working properly.

In any case, it's not a starter switch problem. I have completely removed the starter switch and wiring from the solenoid's power terminal and S terminal. I'm now jumping the solenoid's power terminal to the S terminal with a metal object to act as the switch.

New engine sounds good. Or maybe just a new boat. Or just sell the boat and use friends' boats? Haha, yeah: joking. At last I'm learning a ton about the Perkins 4-108 engine.

[skipmac]

I have had starters stick a few times over the years but always one of the already suggested cures did the job. Please make sure to let us know when (note I say when and not if) you find the solution.

[beebopbogo]

Upon further reflection, it can't be a bad solenoid. It tests normally on the test bench. And when removing power from the S terminal, the electromagnet is deactivated. It must be hanging on the flywheel while under load.

I like the bad alignment diagnosis. Now how to straighten her out??