1992 sea sprite fire

[Boater1998]

Having some issues with my 1992 Sea Sprite it has a 305 mercruiser I was going down the river at 2200 rpm and I noticed smoke coming out of my vents so i quickly turned the engine off and looked at my gauges all of them where within the normal limits by then the inside of the Cuddy cabin was so full of smoke you could not see so I decided give the very back of my engine a shot of the fire extinguisher I could not see flames but I could hear stuff burning and cackling and loud popping noises followed by unknown objects hitting the sides of my boat after each pop so after I pulled the boat out of the water the exhaust bellows where completely fried and the transom was cracked just looking for some answers on what the popping noise could have been and what all I should be expecting to be wrong and how pricey it will be to fix it

 

[Bondo]

Ayuh,...... Welcome Aboard,...... My WAGuess is,.....

The incomin' water, Stopped, for some reason, 'n you experienced a severe massive overheat, which caught the exhaust rubber on fire, blowin' out the connections,.....

 

[Boater1998]

Okay thank you

 

[Scott Danforth]

in addition to all the rubber bits in your exhaust system from the hoses to the flappers and the bellows, you may need new motor if you overheated it that badly.

 

[QBhoy]

Oh jeez...that sounds like terrible luck. Don’t hate me for saying or assuming that at 2200 rpm on that boat and engine you were likely at its highest threshold of load on the engine. Not planing, bad cooling circumstances and really pushing flat surfaces through the water inefficiently. I’m only saying this because my boat will only just plane at 2200 rpm with a pretty highly pitched prop, bigger than usual motor for an 18ft...so maybe presuming yours wouldn’t be Planing and really lugging the load on the motor...likely not of any help telling you now, but you know what I mean.

 

[Boater1998]

I wasn’t running the boat hard at all I take very good care of any boat I own 4000 rpm is Top speed and I’ve only ran that once just to see how fast she could go I have to go around 3000 just to get it on plane and I back off from that just so I don’t even have to run it that hard

 

[Bondo]

4000 rpm is Top speed and I’ve only ran that once just to see how fast she could go I have to go around 3000 just to get it on plane and I back off from that just so I don’t even have to run it that hard

Ayuh,...... Yer Severely Luggin' yer motor,...... You should be seein' 4800 rpms at Wot,....

 

[Boater1998]

Their must be something wrong with my boat before hand because anytime I try to go over 3000 it sounds like the motor is going to explode

 

[Boater1998]

[No message]

 

[QBhoy]

I wasn’t running the boat hard at all I take very good care of any boat I own 4000 rpm is Top speed and I’ve only ran that once just to see how fast she could go I have to go around 3000 just to get it on plane and I back off from that just so I don’t even have to run it that hard

Running it at 2200 is pretty hard. It will be very inefficient and pushing a lot of water. Running it on plane at more rpm will have less load

 

[Boater1998]

2200 is on plane

 

[Boater1998]

For my boat

 

[Lou C]

Well it sounds like the exhaust system was not getting any water whatsoever, in that last pic was the exhaust bellows vaporized? Hard to imagine the engine did not overheat. What's the rest of it look like? If the engine got as hot as the exhaust, figure on at least, blown head gaskets and cracked cyl heads.

 

[Boater1998]

Well the transom got so hot it is now cracked and the you had to carefully and quickly pick up the seat that covers the engine to keep from burning your hand I assume something else also burned because the cabin was full of thick smoke and the engine wasn’t even smoking that bad I could not see up under the engine it will have to be pulled out and the popping sounds along with objects hitting the sides I assume that was the cly heads cracking but I’m not sure because I’ve never heard one crack before Lou C

 

[Lou C]

The day my engine overheated, I heard some really bad sounding noises, so much so that I thought it was totally shot. However, once the cooling issue was sorted out it ran fine 2 more seasons, but then blew both HGs at the end of the third season. Post up some pix of what you have.

Also judging by what is left of that exhaust bellows, the driveshaft bellows must also need to be replaced! Scorched by the heat no doubt....
Now I've never taken a Merc drive apart but I can tell you that hot exhaust with no cooling water going through the OMC Cobra drive on my boat not only burned up exhaust rubber parts but also the water tube gaskets inside the drive can be melted. So it's also going to need to be taken apart and checked.

 

[Boater1998]

Okay thank you for the help could anyone tell me about how much it would cost to fix the crack in the transom?

 

[achris]

If it got hot enough to crack the transom, the boat integrity is seriously compromised. If you want to keep the boat, I would remove the drive, engine and transom assembly and have it professionally assessed. Whatever it costs, it won't be cheap.

On the engine only doing 4,000rpm (at wide open), that's why the overheat was so dramatic. You are overloading the engine, at all speeds, with a propeller that is far too big. That overload generates far more heat, at all speeds, so a loss of cooling water has a greater affect on the end result damage.

Chris........