MerCruiser 4.3 Alpha One Taking On Water

[Nebraska Boater]

I have a MerCruiser 4.3 Alpha One. I have used it in past seasons with no problem. But this year when I took it out for the first time we were out for 10-15 mins when I noticed there was a large amount of water in the back of the boat. So I decided to take it back to shore. As soon as I turned the engine back on the water started coming in faster and the engine was not working as well as it should be(full throttle yet barely going 5 mph). As more water came in the boat the engine decreased in power until it finally died. If this helps at all the water that was coming in was burning hot(200+ degrees) and oily. If you have any ideas of what the problem might be please tell me.

 

[achris]

Re: MerCruiser 4.3 Alpha One Taking On Water

Sounds like a leaking exhaust tube.

Chris..........

 

[Nebraska Boater]

Re: MerCruiser 4.3 Alpha One Taking On Water

I am a fairly new boater. Can you give me some more info?

 

[achris]

Re: MerCruiser 4.3 Alpha One Taking On Water

Bolted to the outside of the cylinder heads you have exhaust manifolds. On the top of those are bolted exhaust elbows. On the end of those are a rubber sleeve, called an exhaust tube, that goes to another aluminium tube, then another rubber tube, and finally into the 'exhaust pipe', often called the 'Y-pipe' or 'bullhorns'..... I suspect you have a leaking lower rubber exhaust tube....

Does that make sense to you?

Chris.........

 

[Nebraska Boater]

Re: MerCruiser 4.3 Alpha One Taking On Water

Thank you Chris for your help. I will check it out and get back to you.

Nick

 

[Nebraska Boater]

Re: MerCruiser 4.3 Alpha One Taking On Water

I got a device that hooks up to the boat and simulates it being in the water. When I turned the boat on I could easily see the problem. i am not sure what it is but it is a large leak on the engine. If you could please tell me what it is and how to get a replacement piece used and cheep that would be great.


Nick

 

[NHGuy]

Re: MerCruiser 4.3 Alpha One Taking On Water

That water is shooting out either below the exhaust manifold or between the head & block, or from a missing, spark plug or it even could be from a crack. You need to see exactly where the water is from or show us.
You want to have it be a gasket, but it could be another problem. That will take more detail. Can it be pressurized with air or cool water to find where it is from? Does it shoot water the moment the engine starts? If it does identify where from, and send a pic. The fact that you get oily hot water makes me think you might have a head gasket issue, a crack, or a valve issue that caused the problem. What's even worse is the manifold may have caused the original problem. How does the motor oil look, is it clear or is it milky? Is it at the right level? Is it too high or too low?
It's more of a problem than the first assessment thought.

 

[Bt Doctur]

Re: MerCruiser 4.3 Alpha One Taking On Water

Guess it got cold way up there and some water was left in. What condition was the engine oil.

 

[Bondo]

Re: MerCruiser 4.3 Alpha One Taking On Water

Ayuh,... That boat wasn't Winterized,...
It Froze,+ Split atleast the exhaust manifold, Probably the block as well...

I'd do somemore checking before you buy another manifold,...
Ya probably need a Complete new Motor...