Started engine, then "bang" everything stopped

gbrem

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Started my mercruiser for the first time this season in the driveway. It turned over beautifully but suddenly there was a loud metal "bonk!" sound and now it won't turn over. Just a "tick" sound when i turn the key. Was that the sound of the solenoid falling apart or something else? How do I diagnose?

Details:
Mercruiser Alpha One, Thunderbolt Ignition, 305 Model MCM 5.0 Litre V8
Year is approx 2004
 

Bt Doctur

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Re: Started engine, then "bang" everything stopped

not knowing what you have will make it hard to guess.
 

Bt Doctur

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Re: Started engine, then "bang" everything stopped

Drive may be seized,Drive oil where it should be, remove drive and try again

engine oil level ok, threw a rod, broke a piston ,stuffed a valve
remove valve covers and check for all 16 valve stems and spring integrity
 

gbrem

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Re: Started engine, then "bang" everything stopped

Thanks for the tips. Would the engine not turn over at all with the potential issues you've listed?
 

Bondo

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Re: Started engine, then "bang" everything stopped

Thanks for the tips. Would the engine not turn over at all with the potential issues you've listed?

Ayuh,... Welcome Aboard,... That's a partial list, but a good place to start,...
 

Bt Doctur

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Re: Started engine, then "bang" everything stopped

start with those and report your findings , other include broken crank,cam,.connecting rod, piston,dropped/broken valve,seized drive,hydro-lock, and a couple I missed.
 
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Re: Started engine, then "bang" everything stopped

your first post is a bit fluffy. do you mean that you started the engine and then it went clunk or do you mean you was turning the motor over with the starting motor and it went clunk. If you was turning the motor over with the starting motor when it went cluck then you may have a broken starter motor casting. If the engine was running on its own when it went clunk then any of the above posts could be the problem.
 

gbrem

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Re: Started engine, then "bang" everything stopped

your first post is a bit fluffy. do you mean that you started the engine and then it went clunk or do you mean you was turning the motor over with the starting motor and it went clunk. If you was turning the motor over with the starting motor when it went cluck then you may have a broken starter motor casting. If the engine was running on its own when it went clunk then any of the above posts could be the problem.


I turned the key, the motor was turning over for about 2 seconds (first start-up of the season) and it went clunk and stopped. Now turning the key results in one single "tick" from the starter. Starter motor?
 

Bondo

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Re: Started engine, then "bang" everything stopped

I turned the key, the motor was turning over for about 2 seconds (first start-up of the season) and it went clunk and stopped. Now turning the key results in one single "tick" from the starter. Starter motor?

Ayuh,.... Pull it, Look it over, 'n bench test it,...

If that ain't it, pull the spark plugs, 'n manually turn the motor,.....

If that ain't it, pull the drive, 'n try manually turnin' the motor again,...

If the motor Still don't turn over, Pull it, 'n mount it on a stand,... it's got Problems,...
 

HT32BSX115

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Re: Started engine, then "bang" everything stopped

I turned the key, the motor was turning over for about 2 seconds (first start-up of the season) and it went clunk and stopped. Now turning the key results in one single "tick" from the starter. Starter motor?
Howdy,

Engines don't usually have major failures just sitting over a Winter etc....

Electrical problems sometimes do happen, like poor, loose or corroded connections.


I don't think I would lean toward catastrophic failures until you do a few things.

Try turning the engine over by hand with a wrench. (remove the spark plugs to make it a little easier)

After you know the engine/drive is not frozen, start doing some electrical trouble-shooting.

Electrical power at the solenoid, starter (when you turn the key)



There's only a couple of things needed to turn the engine with the starter.


A good solenoid

Power to the solenoid and power to the solenoid holding coil (via ign switch) .

Good (clean & tight) (+) power connections and (-) ground connections at the battery, engine block and any other ground connections.

Finally, A good starter.
 
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Re: Started engine, then "bang" everything stopped

I turned the key, the motor was turning over for about 2 seconds (first start-up of the season) and it went clunk and stopped. Now turning the key results in one single "tick" from the starter. Starter motor?

This still doesn't answer Glenn pop question. When turning the key to start, the engine will crank or "turn over". When the engine fires up it is now running. Were you cranking the engine for 2 seconds, or was it running for 2 seconds?
 

gbrem

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Re: Started engine, then "bang" everything stopped

Howdy,

Engines don't usually have major failures just sitting over a Winter etc....

Electrical problems sometimes do happen, like poor, loose or corroded connections.


I don't think I would lean toward catastrophic failures until you do a few things.

Try turning the engine over by hand with a wrench. (remove the spark plugs to make it a little easier)

After you know the engine/drive is not frozen, start doing some electrical trouble-shooting.

Electrical power at the solenoid, starter (when you turn the key)



There's only a couple of things needed to turn the engine with the starter.


A good solenoid

Power to the solenoid and power to the solenoid holding coil (via ign switch) .

Good (clean & tight) (+) power connections and (-) ground connections at the battery, engine block and any other ground connections.

Finally, A good starter.

Well, turns out you were right. I was able to turn the motor over with a large socket. Then first thing the mechanic did was short the starter with a screwdriver and the engine fired right up. Seems the remote throttle is corroded and needs to be replaced. After lots of wiggling it finds its happy spot and starts. Still not sure why there was such a loud bang first time around.
 

aerobat

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835
Re: Started engine, then "bang" everything stopped

Drive may be seized,Drive oil where it should be, remove drive and try again

engine oil level ok, threw a rod, broke a piston ,stuffed a valve
remove valve covers and check for all 16 valve stems and spring integrity

maybe we should stop the nightmares when he just CRANKED the engine for 2 seconds... yes, remove starter and look, look the flywheel, turn engine by hand for security it turns .
 
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