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[me3]

Hi all,
Our petrol boat flipped today. We took the spark plug out, flipped the boat and pulled the cord. Got the water out, but couldn't start it. We know that we have, compression, spark and fuel getting into the cylinder. Is there something we are missing?

Reece

[tobyker]

If there's a spark at the plug and fuel getting through (no jets blocked with water globules?) and it still won't start then I think you need to dismantle in case of water ingestion cracking the piston, or buckling the con rod, or the crankcase being full of water. If you fix it or find something, please give feedback for general edification.

[martno1fan]

Also check fuel lines did not get water in them through the carb ingesting water.If you didnt get her started to burn off moisture you need to completeley strip the motor because within hours the bearings will rust and be shot.
Mart

[me3]

Thanks for the advice, we did have a spark from the plug, but we put a new spark plug in, and it starts fine now. We think it must have cracked somewhere when it rapidly cooled in the water.
Reece

[craig dickson]

Hi Reece

I agree especially that it is crucial to get a water soaked engine started again and given a good run to prevent the bearings corroding as Mart said.

However going back to the situation following recovery of a flipped boat: Unless water was ingested via the carb at the instant the engine was revving at speed you would be very unlucky to suffer internal damage via hydraulic lock. I have seen countless flips of boats in race conditions and usually it is just a matter of restarting the engine which as you discovered can be tricky. And if you had suffered internal damage such as a bent con rod for example, you would likely notice something wrong because the engine would not spin over freely with the plug removed. It would not feel right.

Two other key points:
Consider the engine itself..
1) You said that you had spun the engine and got the water out. But did you get all the water out? It pays to fit a spare spark plug after a flip because then you know that this key component is free of water droplets. What about the exhaust system? Did you angle the boat hull at multiple angles when cranking it over to get as much as possible out of the exhaust? And even then it always amazes me when firing up the engine just how much water comes out of that exhaust (trapped within the baffles etc)!
Consider the fuel system:
2) Are you running a solid vented tank? If so it is more likely than not that following a flip, your fuel tank will have taken on water. The only sure solution is to empty the tank and refill with fresh fuel. Otherwise starting and running problems will be almost guaranteed. It takes only the smallest amount of water in the fuel supply to cause issues with petrol engines.

I hope this contribution may be of some additional help.

Cheers
Craig

[me3]

Thanks Craig, all useful information should it happen again! Hopefully not though. As said, we changed the spark plug and it starts very well, runs smoothly and there are no unusual noises. So, I think we were lucky and got away with no damage. 

[craig dickson]

Hi Reece

I appreciate your update, thank you
It is good to know that all is now okay with your engine.

Cheers
Craig