Starting my freshwater flush setup

[Robert Vetrano]

Starting my fwf finally after talking about it for too long. My system is ok for an engine off system and will tap into the OUT port on my seawater pump. Manifold is all Home Depot stuff and will be installed in my transom locker with a quick disconnect for the dockside garden hose. I used 3/4” braided hose from Amazon to run to my engines, and it will reduce down to 5/8” hose and then into the 1/4” NPT fitting on the pump.

The goal is to easily flush when back at the dock and not have to go into the engine room……making it more likely that I’ll flush every single time. More photos to come when finished.

Topic

[Tony Athens]

If you can supply 30+ PSI to the 1/4″ fitting to the pump on the suction side, the engine running at 1000 RPM or less under no load will have ZERO issues as to heat–ZERO –Seacock closed after start, and opened immediately after shut down

If you supply to the pressure side, engine off, obviously zero issues.. Only issue there is whether the exhaust design is right to push water thru it with the engine off.. I would not recommend this type of water feed with the engine running because the impeller will not like it at all..

2 users thanked author for this post.

Kevin Lee, Robert Vetrano

[Robert Vetrano]

Dan, I’ve already built the manifold…..but thanks for the input. I don’t doubt the effectiveness of flushing……and I see where you’re going with the pre-pump flushing. Also, as I’ve read on this forum, you don’t need to close the seacocks to effectively flush the system. Especially with strong dock pressure like we have. I could certainly go that route at this point……it just means fittings on my strainer caps, or Tony’s tees. I dunno. Good stuff to ponder while quarantined, lol.

[Dan]

Robert,
In NW Florida I’ve seen intake hoses/strainers block up with oysters in a couple of years,Ive just pulled my intake hoses off to change them out (its been 5 years) and they where spotless.

The raw water pumps… my engines came with a really badly designed prone to very early failure pumps,Ive just changed my pumps out (1500 hours on pumps and 500 on the impellers) and they appear to be perfect….

My freshwater flush is at the strainer and my equipment is flushed every use with the seacock closed.

Reading you’re going to build a FWF system out of PVC,have a look at the glass reinforced products from Banjo fittings, they are extremely tough, and cheap.

https://www.banjovalves.com/pp-sch80-threaded-fittings.aspx

[Robert Vetrano]

Interesting point. Maybe Tony can weigh in?

[donald roth]

engine off flushing is pretty novel in these parts, and does not offer any flushing benefit to the pump/strainer/intake portion of the system.
The big advantage I see is that engine off flushing does not require full flow to keep the motor cooled, which is a big concern.
Hopefully the 1/4” supply will be enough to fill the coolers, and not just run thru the lowest tubes.
Under normal operation, the flush System plumbing will be pressurized by the raw water pump, so take care!

[Robert Vetrano]

It’s much more than a few $$. Price it out and you’ll see. And either way, this is going to have freshwater going through it…..and is above the waterline…..so I’m not too worried about it. I don’t think the seawater pump will put out enough pressure to screw up a pvc fitting (I could be wrong……but I don’t think the pressure is “that” much, right?)

Tony, I’ll put the fitting on the pressure side of the oem QSB Sherwood pump……or whichever is downstream of the impeller (I think that’s considered the pressure side) This was verified on a prior post of mine about a year ago. The plan is to shut off the mains, hook up the dock hose, and flush each main for a few minutes. I’ve verified (also by previous posts) that I have an all “downhill” exhaust flow after the exhaust shower/mixer.

[Tony Athens]

Hook up to the QSB pumps? Suction side or pressure side?

Explain your plan as to the sequence as to how you plan to flush the mains?

As to PVC vs “metal” –IMO, I personally prefer PVC if all is done right.

[Darrell]

Why not spend a few dollars more and make the manifold out of metal fittings

[Author]

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