Major Problem? Ign off while running.

I highly doubt you did any damage whatsoever to your engine. The quick unloading/loading of the drivetrain, while not good for the transmission, will not stretch rods, break pistons, etc. It will also not cause a condition where your engine will injest water. If the engine was still rotating and you did not come off of plane quickly, how would it injest water? Not possible. The backfire was definitely out the exhaust due to a small amount of gas puddling up with the throttle open. Once the engine had ignition, the gas was lit, the explosion occured, and the gasket blew consequently. Typically though, the gasket should not have blown. It's probably a coincidence.

Fix your gasket and I'm sure you'll be good to go.

Doug
 
All appears well, have not run out in the water, just started and listened. Douglee, same thoughts I had.

Lucknow, I'm sure it made a real racket, but at the time I had 50 MPH winds, 3ft waves and pounding waves, while I was trying to dodge the crabpots in the dark. It was even more fun when I shut down the port and ran the rest of the way at 7 Knots.
 
douglee25 said:
If the engine was still rotating and you did not come off of plane quickly, how would it injest water? Not possible. Doug
Click to expand...

How would a boat, on plane, with water being forced into the intakes by the scoops, be any different than:

Towing a PWC without valving off the raw water intake.

Putting a scoop-type intake on a genset, and not running the genset while on plane.

Either of these situations can force water up into the exhaust system where lack of exhaust pressure can allow it to enter the engines. The PWC and genset water ingestion scenarios are well documented and DO happen. Whether it could happen to a main from a momentary engine shutdown, I'm not sure.
 
tobnpr said:
How would a boat, on plane, with water being forced into the intakes by the scoops, be any different than:

Towing a PWC without valving off the raw water intake.

Putting a scoop-type intake on a genset, and not running the genset while on plane.

Either of these situations can force water up into the exhaust system where lack of exhaust pressure can allow it to enter the engines. The PWC and genset water ingestion scenarios are well documented and DO happen. Whether it could happen to a main from a momentary engine shutdown, I'm not sure.
Click to expand...


Well....

1. PWC's do not have scoops or thru hulls like a typical boat. The pump (jet pump) houses the prop which forces water into a hole bored in the pump housing. With the engine off and the ski being towed in the water, the water flowing past this hole can be sucked up into the cooling line via the venturi effect. Depending on the cooling setup (closed or open), it can flood the exhaust, which ultimately backs up into the cylinder.

2. The OP said the engine never shut down which would further be supported by the fact that he was able to keep the engine running by simply flicking the ignition switch again. He never had to restart. How much time does a typical engine take to shut down? 1 - 2 seconds? For a boat engine to injest water, the same thing must occur as on a PWC. The exhaust/mufflers must fill up prior to traveling up the risers and finally into the cylinder. Again, since the engine never fully shut down, the time frame we're speaking of is less than 1 - 2 seconds. The engine will not injest water in this time frame.

Doug
 
I am so happy for you that everything appears to be ok, At the end of the year this is the day that will stick out as one of the "memorable" days of the year. I am happy all is well with the boat. Enjoy the rest of the season!!!

Kevin
 
just a suggestion.on my 300 weekender the previous owner broke the switches off almost flush with the dash.Now there is no way to accidently hit them but they are still functional to use.Now are a very short switch.
 
Well, I had the boat out 3 times this weekend, and after replacing the exhaust manifold gaskets on both sides, all appears to be fine. For whatever reason, the gasket on the SB manifold was a paper style gasket and was very brittle, but the one on the port side was he Merc style with the silver coating. Oh well, all seems well.
 
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