Another day of great fun... maybe not so much. WTH?!
 

So, I had been enjoying the fact that my engine ran so much better after replacing the intake gaskets and such. Key word, "had."

Yesterday, I stopped at home on the way back to the office, and thought it would be nice to hear the boat running before heading back in to work. Hooked up the water, uncovered her real quick, then went to start her. I got about two revolutions, she backfired out of the blower (did that once the day before... figured maybe a timing issue that I'd get to before going out). Tried to turn her over again, then just grinding. Lots of grinding. As in a jammed starter. Immediately, I feared that maybe I had hydrolocked the engine. Not sure why I thought that, it was just the first thing that came to mind. I pulled all the plugs, and no water. Not even a peep.

I got in there today and sure enough the starter was busted. The nose was broken off and I recovered the broken piece inside the engine cover. i broke out a breaker bar, and to my horror found I couldn't turn the engine. It was jammed. I couldn't turn it in reverse much either (maybe a 1/8-1/4 inch). Fast forward two hours later, after yanking the blower belt and the drive (neither of of which helped), I was able to get her to turn again. Could something have jammed it within the housing?

The question then is... what broke it? Did it kickback and bust it, or did something else jam it? What could jam in a kickback? And she definitely backfired. I'm almost positive that it was the catalyst to the whole thing.

I plan to put another starter on it, then run a compression test to make sure nothing went south.

Seems that I'm cursed or something.

Anyone else encountered something like this?

I wouldn't rule out a valve train issue.

Like a valve hanging open?

Timing chain jumped, piston hit intake valve, incorrect valve adjustment, igntion timing issue, valve stuck in guide, broken rocker arm, just throwing stuff out there.

One thing I learned a long time ago when it comes to roots blower engines.

Pump throttle, return throttle to idle, then crank engine over. I never crank blower motors over with the throttles wide open, like I see so many do with N/A carb engines trying to get them to start.

Not suggesting thats what the problem was, but just throwing that out there.

I hear ya Joe.

I never hold her open to start. I give two or three pumps, let her sit, then start cranking. Usually, no issues.

I guess I'll start looking at the valvetrain.

I'm a firm believer in the KISS principle. Starter rolls twice, backfire blows up starter, starter crap falls inside housing or got caught between the teeth, won't roll over. My first thought is some chunk of metal wedged against the flywheel and held it enough you couldn't turn it with a breaker. AS you messed with it, the little chunk of crap fell out. New starter, compression check it, all good, fire it up. (If it's something else it will let you know quickly) X2 on MT's starting procedure.

I've only run blowers on a car, but something to keep in mind possibly. My blower intake has spring loaded burst panels on it to relieve pressure in case it backfires so the rotors and engine don't feel the shock (hopefully). Marine engines often don't have burst panels because of the explosion risk boats have so blower and engine absorb the shock. That's why marine blowers commonly use a serp type belt because it will slip before something breaks (hopefully). Running a coggeg Gilmer style belt that can't slip combined with no burst panels could potentially cause an issue.

That's what I do with NA motors, that's just good practice, catch the engine with the throttle. Only time I ever hold something to the moon is when it's my buddies rx8 so it doesn't flood when cold....

Thanks for the note. I'm running a 16-rib serpentine belt.

I wasn't sure what you had but figured I'd put it out there anyway. Maybe someone with more blower experience disagrees but it might help someone.