Mercruiser Starter stripped the plastic cup gear that is driven by the three planetary gears?

Hello All,
Here's my situation, took the boat out for the fourth time this past weekend (it has been working just great so far). When we launched it it started great first time, took it out through the channel and into the open water and headed for the shoreline to have a bite to eat. when we were ready to go out again the motor only turned over about a quarter turn then stopped, tried the starter a few times and the same thing happened, partial turn over but no start. after about the six time the starter turned but just whined like it wasn't engaging the flywheel gear. removed the starter tonight and took it apart, found the plastic cup gear that is driven by the three planetary gears completely stripped. New starter needed, but before i just replace it i would like to find out why it stripped, does this happen from fatigue over time. the engine is a 2000 4.3 Mercruiser 190Hp with a GM #PG260-F1 starter, I have owned the boat for 5 years so I don't know if it is the original starter. Is there a way of turning over the engine manually to make sure it didn't seize up, i shouldn't think there would be a reason to seize, it was running fine just a half hour before and all gauges were OK.
Any words of wisdom is always appreciated.

Thank you in advance, G Jackman

I have an information update, I was able to turn the engine flywheel a little at a time with a small pry bar on the flywheel teeth (I know I could have damaged the teeth). Anyways I did remove the starter last spring to give it a good cleaning and check the brushes, I also put some marine grease on the gears & shaft, I may have put some on the Planetary Gears as well. Do you think that the grease softened up the plastic cup gear and that caused the failure.

Thanks again.

The nylon ring gears will fail.
If you are prudent, you can find a HTGR/PMGR stater motor that uses all steel reduction gears.

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the motor only turned over about a quarter turn then stopped, tried the starter a few times and the same thing happened, partial turn over but no start. after about the six time the starter turned but just whined like it wasn't engaging the flywheel gear. removed the starter tonight and took it apart, found the plastic cup gear that is driven by the three planetary gears completely stripped

Now why does this start to sound like a hydro-lock condition. I`ll bet if you remove the sparkplugs and spin the motor over water will shoot out of a cylinder or two.

Hydro-lock? I will give it a try when I replace the starter motor, are there common reasons for this to happen that i should be investigating if I find water in the cylinders?

If there is water in the cylinders it can enter from:
leaking manifold to riser gasket
crack/hole in the riser or manifold
crack/damaged head or head gasket
Should you find water in only 1 side, remove the hoses, plug them, run the motor 15-20 seconds to dry the cylinders and valves, let cool, run again.Then you have to isolate the problem. If the cylinders stay dry with the hoses off, most likely a manifold problem. If water is still present it could be head or head gasket issue.

Thank you BT Doctur & RicardoMarine for the help and info. Looks like I have some work to do instead of taking the boat out this CANADA DAY, July 1st.
And a Happy 4th of July to all the boaters south of me.

Report your findings, inquiring minds need to know!!!!!!!!!!!!!!!!!

Okay, so here is an update.
Replaced the starter motor, pulled all the spark plugs and turned on the ignition and turned the engine over. Found some water coming out of cylinders 2, 4 & 6, turned over a few more times to get as much water out as possible. Used an air gun to blow out the cylinders through the spark plug holes, put it all back together and started it up without water and ear muffs for about 30 seconds, it started good and ran well. Put the muffs on turned the water on, started the motor and ran for about 15-20 minutes increasing and decreasing the RPM's, water temp up to about 150 F, turned the motor off and started it up again, worked fine, tried this about four more times, worked every time. Shut it down for the night (getting late) will try again tomorrow but will pull the plugs first and check. if there is no water this time does anyone have any suggestions why I had water in these cylinders (I did find that the exhaust bellows at the stern drive had disconnected from the drive unit and had an open end to the lake water) could any large waves push water up into the exhaust manifolds while sitting at a dock not running.

Thank you to all.

The "WHY" is unknown at this point but you may have to change the impeller if you ran it without any water to the drive. As little as 10 seconds can destroy an impeller.
If it only happens on 1 side then suspect a manifold or riser problem.But next time just remove the hoses from the manifolds and let them dump in the bilge. dry the cylinders by running the motor for no more than 20-30 seconds and heavily for the motor if its has to sit for a while.
Would need to see some pics of the boat, you need 13 inches minimum from water to riser to prevent water from going up the pipe.
If you do find water again, remove the manifold hoses , run the motor to dry the cylinders. Then remove the sparkplugs.
Remove the large hose from the therm housing side, fill with a garden hose to the top. Let sit and watch the water level.
See if the water lever drops ,and see if it runs out of the sparkplug holes. Yes would indicate a cracked head or a considerable head gasket blowout from a serious overheat.
Let us know.

I agree...... before your next outing, you need to find out how the water was getting into this bank.

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A bit off topic, but I wish that all marine seawater pumps offered a means of momentary disconnection during engine shut down.

During each winter layup, I remove my impellers and do a quick 10-12 second "dry start" to blow my exhaust system dry.
In 10 seconds, we can successfully fog an engine as well.

Another update, pulled the plugs this morning and not water, started up great and ran well, ran it up to temp. about 170 F increasing and decreasing the RPM's, turned it off and restarted, tried this a few times and everything worked great. I will have to do a bit more investigating before i take her out on the water just to make sure.
As requested I have attached a few photos. BT Doctur, can you tell me from the pic of the therm housing is this the hose to disconnect and fill with water?
Thanks

in the first pic, that is correct. when you do this test have the manifold hoses off and the plugs out. Could use some additional info about your
last trip., what were the conditions like, number of persons and gear, how low was the stern of the boat, sea conditions?
I also notice you have the notorious "bat wing manifolds" . might consider doing the update with the center rise manifolds and risers.

Hello BT Doctur, so my last trip went like this, launched at the ramp, continued out through the channel at idle speed to the open lake, increased to cruising speed about 20 mph and headed for the beach, once we were close to the beach I shut down the engine raised the drive unit up and coasted to the beach, pulled the bow up on the sand and had some lunch the water was fairly wavy as there were many boats going by with tubers, skies and such. the waves were probably slapping up against the stern area of the boat. when we decided to leave the beach after we pushed off from shore that's when I had the starting problem and stripped the gear in the starter motor.
Had to go to work today so I won't be able to do any of the checks you suggested until tonight.
Thanks again.

most likely thats what happened, backwash up the pipe. Why not drop the anchor from the bow, pull the boat backwards to say 3 feet deep
and take a sternline to the beach.

I'm hoping that this is the case, on another issue is that the exhaust bellows has pulled away from the drive unit, is there a trick to pulling it back on and tightening the band clamp or is there a special tool, or do i connect it to the drive unit first then the transom unit.

BT Doctur, you made mention of the notorious "Bat Wing Manifolds" has there been any problems related to this style or do the newer style perform better, just wondering.

If they start leaking its impossible to see it untill it floods the cylinders with water

Final Update, I did the other check that BT Doctur mentioned, removing the cooling hoses and spark plugs, filling the hose with water and checking the level next morning. All went well no water in the cylinders, I was also able to get the exhaust bellows connected again, cost me a few skinned knuckles. Took it out on the lake this weekend and all went well, no problems
I would like to thank BT Doctur and everyone else for their input and advise.
Thanks again and Happy Boating!!