Thru Hull Plumbing Question.

[Carter Powell]

When using thru hull plumbing on a sportmaster lower to feed water should the original three water pickups be plugged or is there enough volume that it should not matter. I am really considering this and just want to make sure I don't screw anything up.

Many thanks, Carter

[FUJIMO]

leave em be.

[aggiestckl]

When using thru hull plumbing on a sportmaster lower to feed water should the original three water pickups be plugged or is there enough volume that it should not matter. I am really considering this and just want to make sure I don't screw anything up.

Many thanks, Carter

I welded them shut as have many others. If you Dont weld them shut install a check valve on the inlet to the pickup

[Carter Powell]

OK I am confused! If they are left open what would or could happen. If closed completely what should I expect. Open or closed?

Thanks, Carter

[aggiestckl]

If case is really high you cab dump water out if cone if not welded shut and no check valve on transom pickup

[Carter Powell]

Ok, so I can see the need for the check valve to keep water from draining back into the lake. Here is what I am not sure of. If the lower unit pick up holes are welded shut and you have a check valve it would seem that you are running the water pump impeller in a dry mode. If the pickup holes are open you are drawing water directly to the water pump. Would leaving the lower unit pick up holes open drastically lower water pressure if the pick up holes were were out of the flow of water?

Thanks, Carter

[BUZZIN' DOZEN]

You don't need to close them, even if you have them above water line, the water being introduced into the adapter plate will leak enough down to lube the impeller. Where the check valve needs to be is at the thru hull, at idle the water the pump is pushing will go out of the adapter and out of the thru hull until you have enough forward momentum to over come it. Another reason to leave the holes open, easiest way to run on the hose.

[Carter Powell]

Thanks for the last reply, that is what I was hoping to hear. Could you recommend a certain type or brand of check valve.

Best wishes, Carter Powell

[BUZZIN' DOZEN]

just make sure it's a brass, swinging gate


What boat are you putting it on?

[Carter Powell]

OK, just one more question,I promise. If you were going to do what I am wanting to do, what size and type of hose would you use. Also what type of connectors would be the most reliable.

Again, Thanks, Carter

[BUZZIN' DOZEN]

AN #12 and 3/4 npt ,but I'm cooling 2.5's, some folks on the other thread say this is to small for big blocks, I have no experience on them. As far as type of hose, if your chicken about possible blown hose, sunk boat , go with a mild Parker crimped end hydraulic hose, at least for inside the boat, mine are 700psi which is low for hyd. hose but more flexible.
What motor/boat combo are you using?

[Frank Molé]

just make sure it's a brass, swinging gate


What boat are you putting it on?

I have that one

[BUZZIN' DOZEN]

Frank, your running a big block, what size fittings/hoses do you have?

[tux974]

Frank, your running a big block, what size fittings/hoses do you have?

Jeff, let me help Frank since I worked on it. Hose, valve and fittings are all 1" ID with a sweep going into the plate.

[Mr. Demeanor]

If case is really high you cab dump water out if cone if not welded shut and no check valve on transom pickup

What happened to your thread?