Alpha one water ejection???

I know this will be a stupid question for most but I'm new to boating. When I bought my boat the exhaust bellow was ripped and off....I took it in and had them replaced. A friend of mine had told me the exhaust and water mix and exit thru the center of the prop....well now with it fixed the exhaust exits thru the prop but the water exits on both sides of the drive thru little ports....just wanted to make sure this was correct.

Thanks for answering my stupid questions guys...I'm learning so much from all of you helpfull people

thanks
Doogie

Re: Alpha one water ejection???

Are you sure you're not looking at the water intake screens?

Re: Alpha one water ejection???

Yeah...those are on the lower unit what I'm seeing is right under the pivot area...the stationary part on the back of the boat and there is none coming out of the prop.

Any help is greatly appreciated

Thanks
Doogie

Re: Alpha one water ejection???

There are (usually) two exhaust relief ports on the bottom of the transom mount, and exhaust and water coming from those is acceptable. Some should come out the prop as well, depends on rpms I think.

Re: Alpha one water ejection???

yep, it's doing what it's supposed to do.

Re: Alpha one water ejection???

OH ok...that makes me feel better. I put it in gear and took it just over an idle and non still came out so I wasn't sure...just made me a little nervous. So why does it have these relief ports instead of it always going out through the prop???

Thanks guys,

Doogie

Re: Alpha one water ejection???

They are called "Idle Reliefs" . They are closer to the surface than thru the prop. If the idle had to push the exhaust thru the prop, it wouldn't idle. At speeds above idle, there is enough pressure thru the prop, but still, some comes out the reliefs.
It's not a problem and is quite normal, and it doesn't matter if it's OMC, Volvo, or Mercruiser, they all have it in one way or another.

Re: Alpha one water ejection???

I have heard a couple of different explanations, both dealing with overcoming the extra back pressure the engine may encounter as it tries to push the exhaust out all the way thru the prop at idle. The prop exit is underwater so there is more resistance to the exhaust pulse. At times the water pressure from waves or backing up is more than when just floating and the exhaust needs another way out until the revs come up and the engine can push back.

Re: Alpha one water ejection???

Synchronized posting it its' finest form.

Re: Alpha one water ejection???

don s said:

If the idle had to push the exhaust thru the prop, it wouldn't idle.

Click to expand...

Not 100% true.... maybe 99 though.....
pre alphas do not have idle reliefs... and they idle just fine....
Having idle relief ports lets the engine idle more reliably...
If it idles through the prop... in your in dead calm water... the exhaust has only so much backpressure on it (as measured by the volume of water on top of it) that it has to push out of the way in order to idle....
If the seas are bouncing, and you have water running right up the transom before the boats own boyuncy can lift the boat, you essentially have a greater volume of water on top of the exhaust pipe... and so more backpressure. If there is to much backpressure it wont start let alone idle. (think banana, potato, or snow bank up a tail pipe)
Idle relief ports just help the exhaust cycle work a little bit more reliably