External Raw water system flushing setup?

[Blue Nose]

Does anyone have any experience desiging and installing a flushing system for the raw water cooling system on their diesel? I would like to have a durable and effecient way to connect a hose to my raw water system from the cockpit. That way I could flush the system with freshwater after use.

 

[alexco38]

Put a bronze "T"

Put a bronze "T" after the thru-hull inlet and connect a ball valve and length of hose led to the cockpit. When you need to flush, just dip a hose in a bucket of fresh water, switch two ball valves and flush away.

Same set up as winterizing with anti-feeze.

 

[Tim R.]

I am not sure what you mean by "connect a hose" but do not connect a pressurized hose to the intake side of your raw water pump. It will likely push water past the waterpump seal into the engine.

Alexco has the right idea. Pressurized hose into a 5 gallon bucket and then a hose from the bucket to the Tee.

 

[Rob19574]

Yes. I assume you have a fresh-water system on your boat?

If so - just tap into that line (prior to the pressure pump if you have one) and "T" that into your raw-water line (between the seacock and raw-water pump). You will need to install a shut-off value on this line so you can switch from the raw water intake to the fresh-water intake. Be VERY careful with this set-up and ensure that you always have the valves closed when they should be. If you accidentally leave the raw water seacock open and the fresh-water bypass valve (at the same time) sea-water will enter your fresh water system and could potentially sink your boat. What I do on my system is as follows: after a day of sailing / motoring - I 1) run the engine, 2) simultaneously open the fresh-water bypass line AND close the raw-water sea cock , 3) let it run for 5-7 minutes, 4) shut-down the engine and close ALL valves.

Very simple to do and costs the price of a 1-foot hose, bronze "T" and ball valve.

- Rob

 

[Stu Jackson]

If you have a freshwater cooling system on your engine (i.e., HX), there is no reason to do this after each sail. However, if you need it for winterizing, it is a good idea.

 

[Maine Sail]

Does anyone have any experience desiging and installing a flushing system for the raw water cooling system on their diesel? I would like to have a durable and effecient way to connect a hose to my raw water system from the cockpit. That way I could flush the system with freshwater after use.

Blue Nose,

While flushing it certainly can't hurt I don't know that the time spent doing it after each sail will yield much if any cost savings or long term benefit. Hundreds of thousands of boats sail and motor in salt water with no flushing of the raw water side of the system. My own engine has 3K hours and the HX was still looking decent at 2800 hours..

My Preference is to not to have a garden hose adapter/fitting. I just spent about 20 minutes last week discussing this with the Forespar rep. I was basically asking him to warn customers or put some notification that a pressurized garden hose should not be connected to their Engine Flushing Valve. The rep had no idea about what waterlocking an engine even was or that it was bad to connect pressurized water to a wet exhaust system marine engine.

When you install a garden hose fitting, people, future owners etc. tend to connect garden hoses to them. This happened to a guy at the boat yard last spring, though this was not the first time I have seen folks fill their engine with water but the only time I had seen it with a product specifically manufactured to do so. He was very proud of his new Marelon flushing valve and proceeded to connect a garden hose directly to it and water locked his engine. Raw water pumps are designed to pump, not be pressure fed.

Installing a flushing tee is easy but one should never connect the raw water system directly to pressurized water or engine damage can result including filling the cylinders with un-compressible water and hydrolocking the engine.

Also, any bucket you suck out of should be lower than the siphon break on your engine. If not, when you shut it down, it could siphon the contents of the bucket into the engine. It is a good practice to simultaneously pull the hose from the bucket and pull the stop lever at the same time or within a close proximity of time, like seconds if your bucket is higher than the engines siphon break.

 

[Old Skool Neil]

In line with Maine Sail's post, here's a pic of my flush system. I connect a 3 foot garden hose to the fitting pictured and place the other end in a 5 gallon bucket filled with fresh water. The bucket sits on the cabin sole. With the engine intake thru-hull closed and the blue handled valve in the pic open I start the engine and run it until the bucket draws down to about 1" of water.

As a side benefit, using the same technique I acid flush the engine every other year (I'm raw water cooled - no HX). Keeps everything cleaned out pretty well.

 

[Ron20324]

I tee'd mine down at the intake seacock, down low so a short piece of garden hose will act as a water pickup to use the engine as a bilge pump. Or, the short piece in a bucket can be used to flush the engine or add the winter anti-freeze.

Rob, I think most people would not like the idea of linking the raw water and fresh water tanks. This is stringly discouraged over on the Peggy forum. Not only, as you say, you might sink the boat, but nasty little organisms can sicken your entire crew should the tank water get contaminated.

 

[alexco38]

Here is a pic of my flushing T. It's mainly used for winterizing but sometimes when we get to a harbor with very dirty or muddy water, I flush the engine with a bucket of water before settling for the night. Just a peace of mind thing.

 

[Rob19574]

Ron - good point there re cross-contamination and potentials of allowing raw-water in to sink your boat. I've actually thought about adding a completely separate tank for flushing that would be dedicated to this. I'd located above the waterline. Easy way to fresh-water flush, acid flush or winterize - thinking a small 3-gallon tank.

- Rob

 

[Paul F]

Easy engine flush - Our head is in the stern and made this connection from the sink easy. If your galley sink is close that could work as well. Place a tee with a shut off valve on the sink's drain. Using this divert the drain water to the engine intake hose with another tee. Put shut off valves on this line and the seawater intake line. To use close the sea intake line. Then open the sink drain line at the sink and at the engine intake and run water into the sink. That's all there is to it. Remember to reset the valves after flushing the engine and shutting it down.

You can open the fresh water line with the engine running using this sequence 1. open the sinks drain line to the engine. 2. Run fresh water into the sink 3. open the fresh water valve to the engine. 4. close the seawater valve to the engine. After you are finished make sure all valves are returned to the normal position

 

[Blue Nose]

All great ideas. My engine does have a heat exchanger so it is just the raw water system that I would be flushing. Stu, I'm not sure why you said a system with a heat exchanger wouldn't benefit from flushing? Could you explain? They put pencil zincs in the heat exchanger so I would think there is some concern of corrosion.