Bravo III - why both seacock and sterndrive water pickup?

[latimoda]

PLEASE HELP ME UNDERSTAND! I am just getting very familiar with my Mercruiser I/O 5.7L Horizon engines. I have two seacocks/strainers for seawater intake (one for each engine), and obviously the dual-water pickups on the lower units. I am learning that not many other engines besides the Bravo III's have both. What is the purpose? Also when winterizing, after I flush the system with garden hose/muffs and draining the block/pump...do I close the seacock before adding antifreeze? Otherwise the antifreeze would come out of the seacock??

 

[Don S]

Re: Bravo III - why both seacock and sterndrive water pickup?

According to the Mercruiser applications manual, the dual system is used with Bravo drives as they get used for high speed applications quite often. also because the pickups could be out of the water if trimmed up just a little to high. Either case would suck air and cause an overheat.
Normally, according to Mercs recommendations, there should be a Y valve so one system or the other is used. It should not be used with both pickups open.

 

[latimoda]

Re: Bravo III - why both seacock and sterndrive water pickup?

Thanks Don. No Y-valve anywhere and the seacocks are left open all season while boat is in the water. So I'm assuming raw water is cooling the engine from both intakes? Do you have a link to the apps manual where it talks about seacocks?

 

[Pete104]

Re: Bravo III - why both seacock and sterndrive water pickup?

Can you post a pic of the plumbing?
Are you absolutely sure that you aren't looking at a strainer for something else?
What manufacturer produced this boat?

 

[latimoda]

Re: Bravo III - why both seacock and sterndrive water pickup?

Pete - The boat is a 2006 300 Searay Sundancer. Picture of the starboard side floor of engine compartment is below. The top strainer/seacock is for the Kohler generator. The one in the middle is for the AC/Heater unit. The bottom larger one pipes directly into the starboard engine. On the port side of the floor (not pictured) is another large strainer/seacock piping into the port engine. They are definitely not being used for anything else. Interesting setup huh?

 

[Don S]

Re: Bravo III - why both seacock and sterndrive water pickup?

Is there a shutoff valve on the intake hose from the outdrive? Somewhere between the Y and the transom shield?

 

[latimoda]

Re: Bravo III - why both seacock and sterndrive water pickup?

No shutoff valve. And the boat was just de-winterized with water muffs on the outdrives, so we know they are sucking water as well.

 

[Don S]

Re: Bravo III - why both seacock and sterndrive water pickup?

Well, I guess SeaRay did it their way, and decided not to follow Mercs recommendations.

 

[latimoda]

Re: Bravo III - why both seacock and sterndrive water pickup?

I have the merc repair manual and seloc manual, but nowhere do i see talk of the seacocks or these Merc recommendations you talk of. Where can I find any written data on it?