# Yamaha 25 2 Stroke water flow from exhaust relief ports



## Palomar (Aug 24, 2015)

I know a lot of folks here are running Yamaha 25 2 strokes or have in the past.

How much water discharge do you get coming out of the exhaust relief ports, the ones just below the bottom cowling, when running at WOT.

None? Spray? Steady stream?

I recently put a new prop on mine, ran it yesterday for the first time and was looking back to check the tell tale. It was the same as before, but now i have steady streams of water shooting out a few feet from the exhaust ports. I do not recall seeing that level of discharge before yesterday. 

thoughts?

thanks


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## jmrodandgun (Sep 20, 2013)

A lot. Mine does it on the hose as well. Not all of the water can go through the powerhead so it has to be able to get rid of the excess water. Mine does it when it has pressure from the hose or when the boat is moving forward. I think the holes are relief holes.


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## Palomar (Aug 24, 2015)

Thanks JM. 

Mine does not do it on the hose. Guess I don't have as much pressure at my house... Just comes out the tell tale. If I am running it on the muffs I can take my hand and place it over the back of the prop and it will start to dribble out of those upper ports though. 

It was probably doing it all along, I guess I was paying extra attention yesterday b/c I was raising the jack plate incrementally testing the new prop.

As I understand it they are relief holes for the exhaust at idle, because the pressure is too high at the foot for the gas to flow through the hub when the prop is not moving, and relief holes for water at high RPM when the pump is working at full capacity.


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