starter problem - I've tried all the obvious things

[nmroadrunner]

I have a 1999 Tahoe Tracker I/O with Mercruiser 4.3L. Last time on the lake it suddenly wouldn't start. I could hear the starter run but motor wouldn't turn over. This was after driving all day without a problem. When I brought it home I went through the usual testing:
-battery is less than a year old and tests fine --fully charged
-pulled the starter out an it works fine on bench testing --bendix pops over without hesitation, starter is about 2 years
-good ground from the battery to motor
-starter solenoid seems okay because the starter will turn over --seems like if solenoid isn't working usually people just hear a click
-all wiring looks good and without corrosion

What should I try next?
Shouldn't the starter be okay in the motor if it bench tests okay?
What am I missing???

Thanks!

 

[stang32]

when you removed the starter, were the bolts loose or broken? how does the flywheel look. any broken teeth? rotate the engine and check the entire flywheel to se if all the teeth are ok.
( heres a very old school test)
put the starter in a vise, have someone attach the wires while you press a broomstick handle on the bendix teeth. see if it operated properly

 

[stang32]

if all looks good, reinstall and report back results, or through in a new starter and get back on the water

 

[nmroadrunner]

Starter bolts are in good shape and were tight. Flywheel looks good, no broken teeth seen with turning the engine.
So with the broomstick test --am I trying to see if the bendix will pop over against the resistance of the broomstick?

 

[Maclin]

If you can get to them easily, remove the sparkplugs to see if water comes out. If you got hydrolocked then the starter may have tried to turn it over but couldn't, now just skips out, hopefully not a flywheel tooth missing.

 

[nola mike]

I'm a bit confused--is the bendix engaging the flywheel? Doesn't sound like it by your description, but if not I'm not sure of the situation that you're describing...

 

[nmroadrunner]

No, the bendix is not engaging the fly wheel. There's no grind, click or other indication that the fly wheel has been engaged. I don't think it's hydrolocked --just doesn't make sense for how/when the problem occurred and doesn't fit with the symptoms.
My suspicion is that it's a wiring issue. Or that the starter bench tests okay but for some reason the starter solenoid doesn't function when it's connected to boat wiring. If someone has a suggestion for what to check with wiring connections I'm open to ideas.
I could certainly swap out the starter --but that involves buying another starter and I'm not really sure if the one I have is defective.

 

[Silvertip]

If you think it's a wiring issue, why would you consider a new starter. If it works on the bench, then fix the wiring.

 

[alldodge]

Take the solenoid off the starter and look at how its attaches to the lever. Then look at the lever for issue of how it moves the bendix. Sounds like a linkage problem or cotter pin missing/damaged

 

[kenny nunez]

If the starter is a PMGD style either the drive needs to be replaced or the internal gear drive is the problem. A worn out drive will pass the broomstick test most times.

 

[stang32]

wait, in your OP, you said you hear the starter run but it doesnt engage the flywheel. if you turn the key and the starter spins(regardless of if it engages the flywheel or not) then you do not have a wiring problem, you have a starter problem

 

[nmroadrunner]

It turned out to be a problem with the bendix. On bench testing I could see the bendix come out but after trying the "broomstick" technique of using a small piece of wood it wouldn't engage under pressure. I replaced the entire started with an old one I had sitting around that needed a little tuning up. Boat fired up just fine after that.
Lesson learned: with bench testing see if the bendix will engage even under pressure/resistance.
Thanks!