Thru hull intakes

My mechanic at my marina is recommending I install thru hull intakes on my 2001 Sea Ray Sundancer 310twin I/O Mercruiser 7.4 with Bravo 3 outdrives to increase water flow into my engines sealing off the drives intake into the engine and letting the drives self circulate when underway. What about using drive showers? Has anyone done this or any thoughts on it? Thanks

yes - i did it - no need for drive showers if you cut a section out of the transfer hose (be very careful of the bellows when cutting the hose.....

It's not clear from your post if your concern is the cooling of the drives, or the cooling of the engines. What your mechanic is talking about is the cooling of your engines. Drive showers have nothing to with the engines. Obviously, we are not him, so can't really comment on WHY it's being recommended. Did you ask him "why"? If it's because you're getting decreased flow to the engine and he's identified the intake cooling hose as the issue, then he is spot on with his recommendation. Heck, even just doing this mod as a precaution is not a bad idea, at all. But, yes, he's correct that the drives can be left to "self circulate". Besides, drive showers only help to cool the top of the drive.

Your signature doesn't say where the boat is used? Salt? How long has it been in salt?

This boat is in salt -south shore Long Island sine 2001. The modification was not for any reason except that the drive intakes can close down over time and threw hulls are more water and as PM.

I did this a few years ago.
Lots of room in the bilge so i mounted Sherwood pumps on the crankshafts like on a volvo.
4 little screws to remove the impeller cover. This has saved me hours compaired to maintaining the mercruiser seawater pumps.

Id like to see how he gets the block off plates installed where the original hoses were attached.

There's a newer hose setup for the part that goes through the drive and has been doing well... so far. But a thru-hull intake with seacock and strainer is still a great idea.

Mercruiser makes the parts to block off the cooling water from the drive to the engines. If you look up "Jack Shaft" parts you should be able to find them. I have this set up on my 23' Cobalt and it is a Mercruiser set up. Mine is an Alpha but they make the parts for the Bravo drive as well....Not sure about the Bravo 3 but its worth a look.

Already cut the hose behind the transom plate. Temporarily plugged the hose that went to the sea water pump.

Also have the parts for the block off plate.
I think I'm going to have to take off a lot of stuff or pull the engines to install them. Need to hire a really skinny guy with long arms to get the hose fittings off and block off plate in. Unless there is a secret way to do this that I haven't found yet!

We just did this 2 weeks ago. Port engine was running hot at higher rpms. We have 496mags w/ B3 drives. At 3800+ rpms was running 180s. Poor H2O PSI also when running at higher rpms. Bravoitis was the culprit. The hose collapses due to corrosion in the drive. You can diagnose it by taking the elbow off at the transom assembly. It will be obvious.
My mechanic at Colton's Point Marina recommended and installed thru hulls w/strainers on both motors. They T'd the drive hose into the thru hull hose so that still pulling some sea water thru drive. I also added drive showers to help the B3s (had them on my last boat).
Engines now run at 170 at idle and up to around 1500 rpms. When cruising at 3400, temps at 165 or so, at WOT, remain at 165 or so.
Pricey addition, but certainly fixed the issue and motors getting plenty of sea water now.
I will probably repair the drive hoses with the new kit next timed I take them down that far for PM.
If you are not having a overheat problem, curious as to why doing it now. Having both engines done on ours (2006 340) was $3000. Make sure they tie them in to your bonding system.

Also, these were installed with engines in and done in 3 days.