Starter spins, engages intermittently for fraction of a second (sometimes)

[Chattaboatit]

1998 Mercruiser 5.0 4M11025LS.

Starter will spin without engaging the flywheel. After a few tries it "might" hit and turn a degree or two. Replaced the starter (complete assy) and it is still doing the same thing. 2 brand new (2 days old) deep cycle batteries, dremmeled the connectors on the battery cables and on contact points to starter motor.

Boat has been out of water in my driveway for 4 years. Trying to get it to crank and probably keeping the original starter turning too much could I have fried another component?

 

[Bt Doctur]

pull the starter and inspect the ring gear teeth

 

[Chattaboatit]

I used a bore scope from my other hobby and they look to be ok.

 

[Scott Danforth]

Inspect the starter bendix

 

[Bt Doctur]

Pull all the plugs and then scope the cylinders for rust , maybe it wasnt winterized correctly
If the starter just spins, the bendix is shot , the planetary gears are shot, or the ring gear teeth have issues
If the motor is seized then it would take out the starers drive almost instantly
Locate an old drive input shaft and weld it to a T bar pull drive and insert into coupler and try to turn the engine

 

[Chattaboatit]

I'm kind of at a loss. Engine was turning over, running pouring gas directly in to carb and sounded as good as ever. Fuel pump wasn't working so I replaced it. Finally got fuel flowing but was old gas in tank. Ran starter too long and killed the first one, that's when I replaced it and the new one is spinning without engaging too. Will snap some photos of teeth when my back, neck, hands, legs, etc recover from messing with it. To be in my 20's again!

I know one of the small wires triggers the solenoid, what does the 2nd on the other side do?

 

[Bt Doctur]

the 2 small lugs are yellow/red from the ign switch and ground, the large ones are Red/Purple 12v and yellow/red large wire to starters solenoid

 

[H20Rat]

I know one of the small wires triggers the solenoid, what does the 2nd on the other side do?

Viewing the starter from the end. Lug nearest the starter goes to the starter obviously. Next wire clockwise is a +12v output when cranking that goes to the coil and fuel pump. Next up is the battery input, and last clockwise is your +12v from the solenoid that fires when you turn the key.

So the other option with a starter that just spins is that the solenoid that pops the gear up is bad &/or stuck. It is entirely possible and actually somewhat likely for this to happen.

 

[Bt Doctur]

thought you were asking about the slave solenoid, not the starter solenoid

 

[kulle]

Pull all the plugs and then scope the cylinders for rust , maybe it wasnt winterized correctly
If the starter just spins, the bendix is shot , the planetary gears are shot, or the ring gear teeth have issues
If the motor is seized then it would take out the starers drive almost instantly
Locate an old drive input shaft and weld it to a T bar pull drive and insert into coupler and try to turn the engine

My engine was seized a bit and I think i broke my starter. I was able to un seize and easily turn motor by hand, even with plugs in. I had run the engine with plugs out and the starter engaged and pumped out the "Stuff" - put plugs back in and fired up and engine jumped a little then starter spun. Suppose I damaged a "clutch" in the starter, I ordered a new one - hasn't arrived yet. See my posts.

 

[wellcraft-classic210]

That " Stuff " could be the sign of a problem if its water getting into your cylinders.

You may want to invesitgate as that can kill an engine in short order

How is you oil -- is it clear and transparent ? -- If its not transparent and light brown that's another sign of water entry in the engine.

 

[Bt Doctur]

If you had water connected could you have had a hydrolock