Mercruiser 5.7 with carb and Gen 2 Alpha one overheating, smoke, taking on water

[clearmarine]

To make a long story short... Yesterday I ran the boat for a few hours on the lake with no issues, headed back to the ramp, I decided to kick it and she ran like a champ..... Until she started overheating minutes later. Alarm started going off so I backed off the throttle and the heat kept going up. I cut it off for a second, smoke pouring out from behind the speakers and out from under the motor and realized that the bilge was going and the boat was filling with water. I had no choice but to start it back up to see if I could get it close enough to shore to swim it in.... And I did. The temp was up to 220 while I putted over to shore. Don't yell at me... I didn't have a choice. 6 kids in a boat, in the middle of the lake, with a bilge randomly going after overheating, I didn't want to risk sinking. The drive oil reservoir is still full, no water in the motor oil and nothing was coming out of the block from what we could see. I haven't hooked it up to the muffs. Once it was turned off it no longer took on any more water and we were able to walk it to the ramp and get it on the trailer. I am assuming the impeller is fried, or maybe the circulation pump just decided to stop working. I read it could be the heat exchanger but I don't think I have anything like that on my block. I took off the L shaped hose to the circulation pump off and part of the metal spring on the inside had broken off. There was nothing in the circulation pump from what I could see but I haven't taken it off to check it. Any other ideas as to what I should check or do next? We heard cracking and popping coming from the block until it cooled off. I'm assuming it was just the oil, but I'm new to all of this. I was hoping it was just a hose that blew off somewhere, but I don't think I'm that lucky. Any and all help is appreciated.

 

[wshekar]

Why was the boat filling with water? It sounds like a hose may have gotten lose or an issue with a drain plug. Did you look around to see where the water was coming from?

I don't think it is a coincidence that your bilge started to fill with water at the same time the engine was starting to overheat...

Your impeller was probably working if it was filling your bilge with water.

What type of engine do you have (serial numbers help)? raw water, close cooling etc.?

 

[clearmarine]

That's what I'm trying to figure out. Definitely not the drain plug. It was fine once I turned the motor off. Bilge never turned on once after it emptied out. The outboard has two serial numbers. 0F401280 and
0F378516. The only thing I can post about the block is that it's a GM 5.7 350 with 4 barrel carburetor. It has a casting number. No serial number I can find. GM 10243880 5.7L V8 1995-99 Small Block

 

[wshekar]

Below is a link to where the serial number can be found:

Mercruiser Serial Number & Mercury Outboards Serial Number Search Location Catalog | PerfProTech.com

Location to your Mercruiser Serial Number or Mercury Outboard Serial Number to Buy Discounted Mercruiser Parts & Mercury Outboard Parts On Sale at PPT.

www.perfprotech.com

The issue is not likely with the outdrive. I suggest following all the cooling system hoses to see if something broke free or has a major split. There is no other reason why water would be filling up your bilge with the engine on.

Also, 220F is pretty high. You may need to replace the head gaskets now or in the near future.

 

[crazy charlie]

You probably had a hose clamp fail and water from that hose filled the bilge while at the same time was not supplying water to the engine.Check every hose starting with the hose from the transom to the power steering cooler and go one by one from there.Post back results.Charlie

 

[Paintman1960]

How high did the water get?

 

[Bt Doctur]

a severe overheat with smoke sounds like you melted the exaust couplings with water coming in. With motor stopped there is no water passing the exaust elbow

 

[clearmarine]

How high did the water get?

Right around floor level. Just replaced the starter last year and alternator this year, so if either goes, it is what it is. It started back up to putt to shore. Is that why you're asking?

 

[Paintman1960]

yup. Dry it out good, Blow compressed air where ya can, give it a shot !!
Check yer oil for water ...
Hopefully ya got lucky

 

[clearmarine]

Below is a link to where the serial number can be found:

Mercruiser Serial Number & Mercury Outboards Serial Number Search Location Catalog | PerfProTech.com

Location to your Mercruiser Serial Number or Mercury Outboard Serial Number to Buy Discounted Mercruiser Parts & Mercury Outboard Parts On Sale at PPT.

www.perfprotech.com

The issue is not likely with the outdrive. I suggest following all the cooling system hoses to see if something broke free or has a major split. There is no other reason why water would be filling up your bilge with the engine on.

Also, 220F is pretty high. You may need to replace the head gaskets now or in the near future.

Thanks. I checked for almost an hour last week and couldn't find any of these. I was definitely worried about running it at that temperature but I absolutely could not risk a sinking boat with 6 kids lol. I didn't know that the water wasn't coming in when it wasn't running, and I didn't feel like pittling around long enough to find out. Once I saw the water in the floor, I just hoped for the best because I knew the bilge wasn't going to be able to keep up. I hope I didn't crack any heads or mess up any valves. It was a risk I was willing to take at the time. I hate it, but as I always say, it is what it is. I'll check hoses again and report back.

 

[wshekar]

Thanks. I checked for almost an hour last week and couldn't find any of these. I was definitely worried about running it at that temperature but I absolutely could not risk a sinking boat with 6 kids lol. I didn't know that the water wasn't coming in when it wasn't running, and I didn't feel like pittling around long enough to find out. Once I saw the water in the floor, I just hoped for the best because I knew the bilge wasn't going to be able to keep up. I hope I didn't crack any heads or mess up any valves. It was a risk I was willing to take at the time. I hate it, but as I always say, it is what it is. I'll check hoses again and report back.

I can understand that. Hard to know if a hose broke loose or a major issue with the bellows during all the chaos.

I would have done the same. Family over a boat.

 

[wshekar]

a severe overheat with smoke sounds like you melted the exaust couplings with water coming in. With motor stopped there is no water passing the exaust elbow

I would think the water coming into the boat occurred before making its way to the engine, which caused the overheat (lack of water). I am sure a lot of rubber ended up melting (flappers, elbows, etc.)