'85 470 starter now grinds, does not turn over...left me stranded...

So...after installing a new power steering pump, brand new used heat exchanger, I got her up and running in the driveway...started right up and I let her warm up--checked for leaks in the p/s and h/x and all was well....took her out on the Merrimac and again, all was well. No overheating, just a top off of p/s was needed.

After about 2 hours of swimming and partying, I started up and it took a few turns of the key....there was a terrible whiiiiiine...but she started. Not 30 minutes later, I tried to start the engine, and only the whiiiiiiiiiiiiiiiine now...no turning over the engine. Eventually, I had to get a tow from by buddy...

Looking back, and recalling that when I installed the h/x, my left knuckle was against the block, and getting "zinged" by an electrical short...the batteries were "off", but something was shorting out. Also, I admit that while installing the h/x, the hix rubbed up against, squished, and possibly messed up the solenoid connections to the starter.

My next time working on the boat, I will pull off and check all solenoid connections, clean them up and attempt a start.

Any suggestions as to what this could be?

Charge battery and troubleshoot with voltmeter, Does the starter engage the flywheel,spin the engine while cranking starter or is starter grinding& not engaging flywheel?Solenoid can be bypassed with jumper cables.

Thanks johnnygjr, for your reply. The starter doers not engage the flywheel...it just whines.

Have you checked for a strong 12volts+ at starter & solenoid after charging battery fully

Did starter ever get wet???

Also, re: "and getting "zinged" by an electrical short...the batteries were "off","

Something amiss in the battery wiring on your boat. I "assume" when you say "batteries were off" that the master battery switch was "off" . Battery switch should be wired directly to battery, and no other connection to engine should be directly to the battery. Sounds like the starter was hot wired to the battery and the battery switch just controls the low current feeds to the system. Or... the battery switch is miswired... Or, you had it on "both" not "off" ... or battery switch defective. Fix that issue first, its a safety issue.

Thanks Cap'n Bob. I'll check it out tomorrow. A friend said that teeth may be missing on the flywheel...he had me move the fanbelt a few inches and lo and behold the starter cranked. Then every 3 seconds or so it whined...I only cranked it a few times. Could that be true?

very well could be missing some teeth, see if you can rotate engine 360 degrees by hand with plugs out to inspect it, If all teeth are there,you have an issue with the starter drive gear.

Now she starts up fine....I just pulled the belt a few inches...I gotta figure out a way to check the flywheel teeth...but found another issue with the circulating pump....new thread.