Hit new starter with hammer?

[beebopbogo]

So I had a leaking fuel hose and my (ex) mechanic burnt the starter out trying to get the darn thing to bleed. Replaced the starter 2 months ago, and just yesterday it wouldn't engage! I tapped it with a hammer and it started right up. I could see that working with an old starter, but my new one? Weird.

More details:
I have a Perkins 4-108 in my 1978 Cal 39, the mechanic burnt the starter out, so I had it rebuilt. After solving the fuel issue the engine has started right up within a half second of engaging the starter here in Hawaii, every time, for 2 months. Then, I was stupid enough in the black of night to hit the wrong button when shutting down and engaged the starter instead. Got a good grinding noise and immediately released the starter button and hit the stop button to shut down. So that's the preliminary.

The next morning I went to start the engine, hit the starter, and all I heard was a solenoid click. No turn-over of the starter. Checked the battery, 100% charge. Tested the lead to the starter with the engine start button engaged and got 12 volts. Ground was solid. So I used my knowledge from driving around my MGB and tapped the starter lightly with a hammer and tried again. Nothing. So I shorted the starter with a screwdriver while tapping and it starter right up.

I'm not too familiar with the inner workings of a starter, but why would a newly refurbished starter need to be hit with the hammer? Could activating the starter with the engine running have jammed the solenoid or something? Brushings stuck? Doesn't make sense. Maybe you smart people could shed some light.

Thanks!

[donradcliffe]

If the voltage across the big starter terminals remains at 12v when you energize the solenoid, the solenoid is probably not pulling in far enough to close the contacts. Buggering the the flywheel and starter gears by trying to start the engine while its running may contribute to the problem, but its pretty common with starters made by the Prince of Darkness (Lucas). There is a screw with an off-center end on it to allow adjustment of when the contacts close, but I've never had much luck with adjusting things. In my case, it I keep trying the starter will engage after 3-6 attempts, and sometimes the hammer makes it work sooner.

In the case of my 4108, I solved the problem by replacing the engine with a Beta. With the Leyland Ford in the Grand Banks, I took everything apart a couple of times, added more starting batteries, and finally gave the boat back to its owner with the problem unsolved.

[glenn.225]

Could be bad contact between the brushes and the commutator or a bad winding and/or several other things . A rebuilt starter may be using the same armature and other parts as your old one depending on the the condition of your the parts and the shop that did it. Sometimes you get a rebuild as good as new, sometimes not. I always check starters before installing, I've had them not work right out of the box.

[beebopbogo]

What test method do you use?

[a64pilot]

I'm betting brushes and armature, sometimes the brushes stick in their holders and cause this. Most probably will be an intermittent problem, if it was re-built the rebuilder has heard of this exact problem before and will surely warranty it. It's a pretty common failure mode

[glenn.225]

Also when you engage the starter with the engine running you can damage the teeth on the fly wheel and starter this can lead to difficult engagement or worst case destroyed teeth that will require replacing ring gear/flywheel or starter drive. Although most times it does no noticeable damage just sound really really bad.

[Tingum]

Is the starter spinning but not slinging the gear into the flywheel? Might be as simple as a squirt of WD-40 on the shaft.

[glenn.225]

Originally Posted by beebopbogo

What test method do you use?

You've just done it. It failed. If the your not up to repairing it on the the boat it will have to go to a shop for testing and repair. If you think you can do without the motor then leave it as is.

On rebuilding starters you need a pretty complete shop with presses, machining tools and a growler. Worked in one once.

[shakey doug]

The 4.108 came out with a couple of different starters the most popular being the Lucas M45G. Your reco shop probably hand fitted the brushes not leaving enough clearance for free movement in the slide allowing them to jam up,shock treatment moves them down the slide onto the armature.Remove the brush cover on the rear end and check for free movement of the brushes if you find a sticky one resize it by filing or sanding.

[gah964]

sounds like a flywheel problem no new starter should need hit with a hammer

[HappyMdRSailor]

Your solenoid is not fully slamming "home" in the start position to fully close the contacts...

Pull the starter, you probably bent the throwing arm for the pinion just enough... Maybe all it needs is a tweak, or a bit of lube... Maybe a new arm...

[Terra Nova]

Replace the mechanic you fired with a competent one. And buy the service manual.

[Eclipsed]

Dis-assemble solenoid and clean contacts that connect the positive cable to the starter windings. This is a common problem with over-stressed starters. The copper contacts burn and leave a black residue that prevents the contacts from working properly. Clean contacts with wire brush 'til they are shiny bright. Re-assemble and try. If no change, think brushes.