4.3 Mercruiser won't crank

[Nautical96]

Hello,

i have a 96 Bayliner Capri Cuddy Cabin (20') i/o with a 4.3 Mercruiser Carbuerated motor. We've taken it out about 7 times this season, and other than getting a new starter and alternator, it hasn't given us any problems....

Went to start it up on Saturday, and now the engine wont even crank...batteries are fully checked and charged, starter is fine. I removed the spark plugs, and tried to manually crank the engine, and it seems to be ceased; The problem with that theory is the day before, i started it up and ran it for a minute or two, and it ran beautifully. The oil pressure and Temp were all normal. I removed the outdrive thinking maybe it was just that with the problem, but it still didn't crank at all. I dont see how an engine can cease without running, especially since it ran fine the last time i used it, and the day before when i started it up. If anyone has any suggestions, i have tried everything i can think of..

Thanks in advance.

 

[JB]

Re: 4.3 Mercruiser won't crank

Mercruiser is an I/O, not an outboard, Nautical.

I will move this for you.

 

[Bondo]

Re: 4.3 Mercruiser won't crank

Ayuh,.... Welcome Aboard,....

Are you saying the motor won't turn over with a Wrench,..?? Even with the Outdrive Off,..??

How about backwards,..??

 

[Don S]

Re: 4.3 Mercruiser won't crank

You running in salt water?

 

[Nautical96]

Re: 4.3 Mercruiser won't crank

Ayuh,.... Welcome Aboard,....

Are you saying the motor won't turn over with a Wrench,..?? Even with the Outdrive Off,..??

How about backwards,..??

Hi, sorry about the thread posting, i saw the I/O section after i already posted in this one.

Yes, the motor wont even turn over with a wrench or breaker bar. It wont go backwards or forwards....even with the outdrive off.

I use it in fresh water.

Thanks

 

[Fishermark]

Re: 4.3 Mercruiser won't crank

I got it to go backwards about a half a turn, but then it shot back to where it was, now it wont go backwards or forwards....even with the outdrive off.

It went back on its own - even with all the spark plugs out? Did any water come out of the cylinders at all?

You might take off the belt and see if any of the accessories are frozen up - other wise it is time to pull the engine and see what's up internally.

 

[Nautical96]

Re: 4.3 Mercruiser won't crank

It went back on its own - even with all the spark plugs out? Did any water come out of the cylinders at all?

You might take off the belt and see if any of the accessories are frozen up - other wise it is time to pull the engine and see what's up internally.

Sorry i worded that wrong, it didn't spring back on it's own, i turned it. Yes, all accessories are disconnected.

Yes, i already took off the belt, and i got the engine to turn backwards, one revolution, but when it went back the other way it got stuck in that one position again and now it's stuck solid, it wont budge either way.

Thanks

 

[Fishermark]

Re: 4.3 Mercruiser won't crank

Almost sounds like a broken rod. But how that would happen after running fine I have no idea.

One thing to try before removing the engine would be to pull the starter - just to make sure it is not binding on the flywheel in some way. Other than that, I'm out of ideas.

 

[Uraijit]

Re: 4.3 Mercruiser won't crank

Yeah, sounds like a broken rod, or cam. Time to pull the engine and see what's up. It's possible to force an engine to start with a busted rod, but it will only run once. Then you'll be buying a new block!

 

[Limited-Time]

Re: 4.3 Mercruiser won't crank

Pull the spark plugs and try turning it over again...

 

[Nautical96]

Re: 4.3 Mercruiser won't crank

Pull the spark plugs and try turning it over again...

Yes, i tried pulling the spark plugs, no luck.

That's what i was afraid of (the rod), and pulling the motor...not going to be fun.

Thanks everyone for your input, i appreciate it. Any other ideas please let me know, i'd like t o try everything before i resort to that.