1999 Mercruiser 3.0L Started on it's own and died?

[wojtek9321]

Hey guys,

I'm really at a loss right now as to what happened overnight. I was getting my boat ready for the season yesterday and put it back in the warehouse. The key was left in the on position but the motor was off. I didn't switch it off, it's my mistake. Engine was not running for 2-3hrs prior to me leaving the boat unattended so it cooled down. This morning I come in and my warehouse is filled with smoke. The engine turned on and ran on it's own, presumably until it seized from running dry. I'm thinking I had a short somewhere that caused it to crank? It sat out in the rain yesterday as we had a quick shower come over us while I was working it outside.

Now when I turn the key it gives me a little click. Battery was drained to 11v when I came in this morning, but I recharged to 14v and I even tried with my battery disconnect switch in bridged mode so my auxiliary battery was used for the starter which was at 14v at rest. I know I'm putting enough juice on it.

Couple questions I guess

1. Anyone know how this might have happened? (Alarm was on so no one was able to come in undetected)

2. If I try spinning my Alpha 1 prop, while the throttle is in drive would I be able to spin the engine by hand? I can't get to the crank pulley to get a breaker bar on it, to spin it by hand. The prop won't budge no matter how hard I try while the throttle is in drive. I'm trying to verify it's seized before I tear the motor to pieces. I'm not really convinced the starter went bad. I think the starter can't turn the flywheel because of the seized condition. Thanks for everyone's time and advice in advanced.

 

[81 Checkmate]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

Thats a sad story......sorry to read it.

Not gona turn the motor over by the prop.......You burned up all the Rubber components in the exhaust….that’s what all the smoke was from

Proly sized the rings to the piston walls from lack of cooling water…So the motor is proly shot…. try to get it to turn over only..i wouldn’t start it till the exhaust rubber pieces are replaced.
Pull the spark plugs and squirt some oil in the cylinders
Pull the starter and hook it up to a battery and see if it works..if good put back on and try to turn over


Your best bet is to pull the motor and rebuild it or get a new long block.

To answer your question....i think it's the ignition switch..not a short that started the boat on it's own

 

[Starcraft5834]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

wow,, that is hard to read........faulty ignition switch can do that huh? what can all readers learn from this? gives merit to those who pull battery connection terminals off battery when you park your boat........... That's what I have learned from this....

 

[Bt Doctur]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

Not unheard of to have motor crank and sometimes start on their own. Best defense is the battery switch.

 

[Starcraft5834]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

Not unheard of to have motor crank and sometimes start on their own. Best defense is the battery switch.

That's a good call.............gonna look into that... can avoid crawling under there to pull battery terminal posts

 

[JimS123]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

I had the starter go on while the boat was running. Turning the key off shut down the ignition, but the motor kept turning over because the starter was engaged. It was under warranty. I forget, but it was either a short in the starter or solenoid?

The only way I got it to shut off was by disconnecting the battery.

Brand new boat with 5 hours on it. So much for debate about not having a kicker. Mine got me home 16 miles that day. At the time we were about 6 miles above Niagara Falls. A good anchor is always a necessity, but a poor backup in some cases.

 

[harleyman1975]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

I would pull the starter and have it checked on the off chance that perhaps the engine did not actually start and that it is only a burned up starter. Will only cost you the time to pull the starter and bench test it.

 

[79Merc80]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

I was at a marine mechanics. He was working on my boat when the boat next to me just started to crank over, no warning AND no key in the ignition. He said it could have been water from the shower earlier that morning, water sometimes gets between the outside of the dash to behind the ignition switch, especially if it's at an angle less than vertical.

Hope this helps.

Craig

 

[Walt T]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

Maybe the boat heard "Edmund Fitzgerald" played over the Muzak got scared and tried to get the heck out of that garage. Ended up dead trying to escape which we see in every horror flick ever made so there's your proof.

 

[Maclin]

Re: 1999 Mercruiser 3.0L Started on it's own and died?

Just thinking about what would have happened after the short circuit, kind of depends where the power got inserted into the circuits...If the engine was just cranking with no spark then the starter would be all out of duty cycles now and maybe be locked up, end the engine would have been subjected to low oil pressures after a while, could have affected lifters/cam and even main bearings. If both cranking and ignition circuits got power and the engine started then the starter would stay engaged and be in the same condition just mentioned, plus all rubber in the exhaust inside the boat would be melted or have even caught fire, flappers turned to goo and now blocking the exhaust exit, pistons siezing, drive could have got too hot and of course impeller and housing, ouch.

So, did the exhaust rubber melt or not? If not then it may have just been the starter crankng away until it died/locked up.