Flow path for exausting cooling water

[gozierdt]

If this is a double post, I'm sorry, but the first one I wrote didn't show up.
Boat is a 1988 Sea Ray 20' Seville, Merc 4.3LX, Alpha One outdrive.

In the outboards and regular inboards I'm familiar with, all the cooling water exits out the same place as the exhaust. This is my first I/O, and I noticed while running on the muffs yesterday, that the cooling water and a good portion of the exhaust while at idle, exit through two ports on the exterior mounting flange of the outdrive. Is this the normal place? I assume it is from the discoloration around these ports, but would like to know if this is normal. If this is normal, what is the purpose of the exhaust through the propeller? Is that the path needed when the boat is running at speed, where there is much more exhaust flow.

Also, I've seen "shutters" mentioned in many threads. I assume these are flaps inside the manifolds to prevent backflow into the exhause manifolds from following seas. Is this correct, and what amount of disassembly needs to be done to examine them. What are the symptoms if they are not acting correctly?

Thanks in advance for the information!

 

[Fishermark]

Re: Flow path for exausting cooling water

That is normal, and you are correct on the purpose of the shutters.

They sit at the top of the "y" pipe. You need to pull the rubber hoses off to see them. There aren't really any symptoms other than some rattling perhaps if they are going bad.