thru hulls on 3300

[RandR]

I plan to add through hulls to improve water flow my 5.0 engines. Typical bravo 3 cooling issue. My question is has anone done this? And where did you put the through hulls? Space is tight for 2 seacocks and strainers

Thanks
R and R

[mmwjr]

While I agree that water flow on the suction side of the raw water pump will be somewhat better the pressure side is unchanged as the restrictions through the engine and exhaust are not changing.

Are you doing this because you think there is a problem?

[RandR]

Yes starboard engine did overheat last year. I found that the engine water pump was recirculating hot water back from the manifolds instead of cool water pushed from the water distribution manifold on the lower starboard side of the engine. There was a sea shell trapped in the bravo 3 water pickup where the hose went through the transom. She'll was removed and the situation improved greatly. But I don't want to have to worry about it again. Bravo 3 has a 5/8 hose that feeds a 1 1/4 hose so it seems it will always starve the sea water pump. I know newer bravo 3 s nave the through hull and leg draw connected with a t fitting.

[mmwjr]

OK but this is true whether it's an Alpha, Bravo I, II, or III and has worked for decades on different engine sizes in a very large number of applications.

A thru hull and strainer can also clog but I guess easier to clear then disassembling the transom assembly.

Thru hulls and strainer are not cheap but if this gives you a better piece of mind have at it.

Not sure I am following you here: " I know newer bravo 3 s nave the through hull and leg draw connected with a t fitting" t fitting? Ting what?

[RandR]

Sorry, to clarify : I have seen newer merceuisers with bravo 3s that draw cooling water through the out drive AND through a through hull. The two hoses are connected with a brass "t" fitting that is then connected to the intake side of the seawater pump.

Back to my original question? Has anyone done this on a 3300 and where did you locate the seacocks?
Thanks

[mmwjr]

Thanks for clarifying, doesn't sound factory.

For installing the tru hull pickups they should be placed in a area that the water flow is clean. I.e. Not behind a running strake. Also easy access in the bilge.

[mmwjr]

Under Photos see speaker dudes pictures. I feel his are to close and may disrupt water flow with each other.

[RandR]

thanks, Space is tight for 2 seacocks looks like speaker dude has them smack in the center of the bilge under the step plate between the 2 engines. I have no idea how he installed them there. he must have really long arms!! I don't know if I can get them there. I am thinking I may have to put one in front of an engine, but I'm concerned it might cause issues with the props cavitating by disrupting the water flow. (although the props are pretty deep below the transom so maybe not)

[mmwjr]

I would not think that would cause an issue. Try looking at some inboards to see how they are positioned.

[shrew]

I have heard of people installing a through hull for an engine pickup on an outdrive before. The reason is the Transom Assembly. The cooling line that passes through the transom assembly gets constricted by corrosion of the transom assembly around it. When this occurs water flow starts to slowly decrease.

The 'proper' solution would be to replace the transom assembly. These average around $2,000 each not counting labor.

You can put a through hull in with a seacock and a sea strainer instead. You can keep the water intake on the drive present, or bypass it completely. If you bypass the water intake on the outdrive, you will need to install a passive drive shower on the outdrive.

A passive drive shower is a set of tubing that scoops water while running and shoots water onto the outside of the drive to keep the drive cool. Without internal cooling water passing through the drive, the drive itself will overheat.

Even if you have both a through hull and are puling water in through the drive, if you are getting restriction in water intake, then it will only get worse over time and you will eventually need a drive shower to keep the drive cool anyway.

[RandR]

Shrew
Thanks. Good to know. I did not think about that!