Mercruiser Alpha1 Gen1 Exhaust

Joined
Apr 25, 2008
Messages
18
Guys,
I haven't had the pleasure of taking apart a Gimbal Housing/Transom Plate assembly yet. Can someone explain why the exhaust on my raw water cooled 1986 5.0 passes through the Gimbal Housing into the exhaust bellows to exit through the prop, but before it enters the bellows, it also has a hole in the underside of the Gimbal Housing next to the transom that cooling water/exhaust also exits? The exhaust/cooling water coming out of the risers into the collector is split into these two paths, just not sure why. Seems like it all should exit through the prop, but there must be a reason it doesn't. Thanks
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,095
Re: Mercruiser Alpha1 Gen1 Exhaust

Ayuh,...

Those are Idle Relief Ports,.....

That way the motor doen't have to overcome the added pressure of pushing the gases down thru the water to the prop...
 
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