Slots above Anti Vent plate

[Bayou Dave]

What are the slots for above the anti-ventilation plate? Part of the exhaust?

 

[Frank Acampora]

I have seen them on a number of engines and never really had the need to investigate. My GUESS would be they are the exhaust relief to reduce back pressure and improve idle when the engine is sitting deep in the water and not moving

 

[steelespike]

I would say for water intake in reverse.

 

[Fed]

Exhaust relief & drainage maybe?
The exhaust tube has a sneaky hole up near the top plus there's the two upper exhaust relief holes.
On the muffs mine lets exhaust and water out of those slots, the water is a little mystery I guess I have some leaks in the water pump, water tube or lower exhaust gasket?


See the sneaky hole above.

 

[Frank Acampora]

FED: The bottom of the exhaust tube is sealed with a rubber gasket and an adapter to the lower unit. The inner leg fills with water to keep it cool to the touch and to keep the exhaust down tube from overheating. (ever see auto exhaust manifolds at night? They glow) The upper hole lets excess water back down the exhaust and out the prop.

 

[racerone]

????------The factory service manual shows that cooling water EXITS from those slots.

 

[Bayou Dave]

????------The factory service manual shows that cooling water EXITS from those slots.

Looking at the manual it appears that water can enter or exit those slots. Nonetheless, no biggee. I was just curious.

 

[racerone]

Those slots are nowhere near the water intake for the pump.-----The water flow diagram shows water flow ( red ) and it EXITS there.

 

[Bayou Dave]

Those slots are nowhere near the water intake for the pump.-----The water flow diagram shows water flow ( red ) and it EXITS there.

OK... got you. I only looked at section 6, not at the water flow chart in the back of the manual until now. Thanks...

 

[Fed]

FED: The bottom of the exhaust tube is sealed with a rubber gasket and an adapter to the lower unit. The inner leg fills with water to keep it cool to the touch and to keep the exhaust down tube from overheating. (ever see auto exhaust manifolds at night? They glow) The upper hole lets excess water back down the exhaust and out the prop.

Thanks Frank now I'm really confused.
I've always thought the sneaky hole was there to relieve back pressure at idle and also to let excess exhaust & water out of the exhaust tube and into the area between the exhaust tube & the outer case of the mid section.

 

[Chris1956]

Idle exhaust relief is the holes at the top of the midsection, in the rear of the motor. They allow mostly exhaust (perhaps some water as well) to exit when the motor is in neutral or low speed in reverse.

The slots above the antiventilation plate exit mostly cooling water. The majority of the exhaust and water exit thru the prop, when in forward gear,

 

[tommarvin]

Is the only water inlet, the very very small black square, on each side of LU. If so its seems way to small.

 

[Bayou Dave]

Is the only water inlet, the very very small black square, on each side of LU. If so its seems way to small.

I thought they looked small too, but they are the only water inlets.No overheating and a strong pea stream so I guess they are sufficient.