D4-260 (on Outdrives) seawater flushing system

[Mike2425]

Hello everyone, my name is Mike and I’ve been lurking about on this forum for the last 5 plus years, it’s great stuff especially if you’re new to boating. I’ve only posted once before this post as being a ‘newbie’ I haven’t felt that I’ve had anything to bring to the table.

I currently own a 2007 Galeon 390 fly bridge with twin VP D4 260’s on outdrives. Being fairly competent on the mechanical side of things I tend to do my own servicing/repairs. I’m looking for validation/criticism on a system I’ve just fitted to my engines.

Having recently changed engine anodes and upon inspection of the seawater system pipes I decided that a system flush is in order. I regularly remove the front anode and drain down the system as it’s easily accessible but what I would like to do is to be able to flush, with fresh water, the whole system so this is what I’ve done..........

With standard (brass) 15mm plumbing fittings and copper pipe capped off with hoselock hose fittings I now have a very easily accessible drain down/ flushing system. I have removed anodes front and rear and now use these orifice as entry/exit points.

My question to you all is, assuming religious regime of drain down and flush, (fresh water at low pressure) what problems or benefits can you foresee with this system?

Thank you in anticipation.

 

[jrudge]

So you have removed the anodes?

I don't think that is such a good idea as

1. when you use it it will be in salt water
2. if you forget ...
3. if you leave the seacock open ( outdrives often don't have one) salt water will leach back in

Several of us have done this, but it is usually an adapter / valve in the perspex of the strainer.

 

[Mike2425]

Thank you for your swift response, I have removed the anodes and am conscious of the fact that should I not flush/drain down there could, potentially, be a problem. As to running the engines for a day at sea, my understanding is that it is the standing seawater that is causing majority of furring up/corrosion whereas flowing seawater would cause little or none of the aforementioned.
I don’t mind being proved wrong and at the end of the day it’s me that will have to foot any bill, I just appreciate you taking the time to reply and giving your opinions on this setup.

Thanks again.

 

[Mr Googler]

I’m not sure I would trust a hose lock non return valve. You maybe have another valve in line but you haven’t said.

Danger is, if you a running along and the hose lock fitting let’s go, youre pumping sea water into the engine bay and losing cooling sea water from the system. Could end up with an overheat or even sea water sucked into the engine..

The other issue (I could be wrong) is that if you are flushing without the engine running, you have no exhaust gas to push the water out. Could you fill up the exhaust riser/ manifold and therefore engine, if the freshwater flow is fast enough. I don’t know how you could tell what flowrate is low enough to give the outdrive riser tube time to empty by gravity alone.

As Jrudge said, why not go into the strainer area? It won’t be all fresh (as there’s no Seacock) but with enough flow, it will certianly be more fresh than salt and the engine is running so no chance of filling the engine with water

 

[GrahamHR]

I put a T piece into the inlet hose to the salt water pump; hose fresh water pressure higher than the salt water head pressure, so a fresh water flush.

 

[Mike2425]

GrahamHR, I did that successfully on my last boat, a single engined, shaft drive D4. When flushing whole system it was easy enough to remove return to exhaust riser and flow right through the system without any worries.
FARSCO, the return/exhaust riser question is the one that I have not yet satisfied myself about. I have sent fresh water through (at half tap pressure) with engine not running without any problem. Perhaps what I’ll do is disconnect seawater to riser pipe and see what’s happening when flushing and if it’s a problem fit a valve somewhere along the return hose. With regard to hoselock connection, my reasoning being hose pipe pressure a lot higher than seawater system pressure, (my understanding being that it’s quantity not so much pressure) I’m happy to give them a go and when running it is only an open loop system, rear connects to front, so not to much strain. ( hope that makes sense)

I appreciate your comments, keep them coming please.

 

[volvopaul]

Hello everyone, my name is Mike and I’ve been lurking about on this forum for the last 5 plus years, it’s great stuff especially if you’re new to boating. I’ve only posted once before this post as being a ‘newbie’ I haven’t felt that I’ve had anything to bring to the table.

I currently own a 2007 Galeon 390 fly bridge with twin VP D4 260’s on outdrives. Being fairly competent on the mechanical side of things I tend to do my own servicing/repairs. I’m looking for validation/criticism on a system I’ve just fitted to my engines.

Having recently changed engine anodes and upon inspection of the seawater system pipes I decided that a system flush is in order. I regularly remove the front anode and drain down the system as it’s easily accessible but what I would like to do is to be able to flush, with fresh water, the whole system so this is what I’ve done..........

With standard (brass) 15mm plumbing fittings and copper pipe capped off with hoselock hose fittings I now have a very easily accessible drain down/ flushing system. I have removed anodes front and rear and now use these orifice as entry/exit points.

My question to you all is, assuming religious regime of drain down and flush, (fresh water at low pressure) what problems or benefits can you foresee with this system?

Thank you in anticipation.

The only fault I can see is that you are not flushing the fuel cooler , the hose area from the strainer to the intercooler.

As the flow passage on your engine is, sea water pump, strainer, fuel cooler, intercooler, heat exchanger , outlet to exhaust elbow . I assume your inlet port is the anode plug on the heat exchanger at the front? If so then the fresh water will divert both towards the intercooler and the exhaust outlet , the water will continue to flow through the system to the exhaust elbow , however the other route will go only to the intercooler , pushing back towards to fuel cooler and sea water pump, for it to cleanse that passage you would have to remove the impeller pushing the water back towards the drive .
The only way I can see a100% effective cleanse is to T into the system just after the sea water pump , possibly just before the fuel cooler , that way the fresh water under pressure will exit at the exhaust elbow.

As to how effective and safe in the fact water would not get into your engine via the elbow can only be tested by doing this with the elbow removed from the turbo.

 

[Mike2425]

Thanks VolvoPaul, taking note of what you said. I don’t like the idea of flooding at the exhaust elbow, could get very expensive if flush pressure is to high. To that end I have thought of inserting a valve/tap in the hose going to exhaust elbow which, when in the no flow position, would mean water entering at front anode hole and exiting out the rear anode hole with no water going toward exhaust. Do you think this method would now pass the fuel cooler as well?

Just a thought, what if I reverse flushed, from CAC back to front anode hole. Would that then pass fuel cooler?

I stand to be corrected !!!

 

[volvopaul]

Thanks VolvoPaul, taking note of what you said. I don’t like the idea of flooding at the exhaust elbow, could get very expensive if flush pressure is to high. To that end I have thought of inserting a valve/tap in the hose going to exhaust elbow which, when in the no flow position, would mean water entering at front anode hole and exiting out the rear anode hole with no water going toward exhaust. Do you think this method would now pass the fuel cooler as well?

Just a thought, what if I reverse flushed, from CAC back to front anode hole. Would that then pass fuel cooler?

I stand to be corrected !!!

Simple NO .

Take a look at your engine , follow the hoses from the sea water pump or read my last post .
The only way to make it work is to follow the sea water flow .

 

[Mike2425]

Thank you for your input, I shall do as you suggest.