When it comes to a marine diesel engine, a freshwater flush is an important maintenance practice. Freshwater marine organisms can cause clogs in the engine, and saltwater or brackish water can cause corrosion. Flushing your marine engine with fresh water will help prevent these issues.

Stagnant saltwater in your engine will leech out zinc, eat away at brass and copper alloys in your pump and transmission cooler, and more. It will also lead to major problems for your aftercooler, as the salt will cause a chemical reaction that damages the metal and compromises the integrity of your expensive components.

Saltwater and brackish water damage to your engine will significantly increase its marine age. So, when you are planning to put your boat away for any period of time, a simple marine engine freshwater flushing will ensure your engine remains in top condition.

 

How to Flush Your Marine Diesel Engine

A basic freshwater flush setup will include a through-hole, seacock, elbow, hose, sea strainer, freshwater flush fitting and a hose connected to the pump. The freshwater flush connection can be placed in the number of places — at the sea strainer lid, on the side of one of the elbows, a T inline valve in one of the hoses and so on.

The most important factor to consider when placing the freshwater connection is where it will be most convenient for you to access — if it’s easy to get to, you will be more likely to perform the flush on a regular basis and thereby extend the life of your engine.

In addition to injecting water into the suction side of your raw water circuit, there are other ways to get the water into the system. For instance, you can use the suction from the pump to suck water into the system. You could also use a vessel such as a bait tank, or inject water into the output side of your pump if you do not have a lift muffler. If you do have a lift muffler, you will need to be careful about how you perform the flush.

Once you’ve introduced fresh water into the suction side of your raw water circuit, follow these steps to perform a flush:

1. Connect your dock hose and turn the water on.

2. When you’re ready to perform the flush, open the ball valve, which will start flushing water out of the through-hole. Make sure the seacock is in the open position.

3. Start the engine and let it run for three to five minutes.

4. Turn the engine off and close the freshwater connection. Leave the seacock open.

This is the safest and easiest way to perform a freshwater flush. If you decide to close the seacock, you will need to be very careful because water flow through the pump can sometimes result in blockages.

 

Get Your Supplies From Diesel Pro Power

For the supplies you need to perform your freshwater flush, trust the wide selection of quality products offered by Diesel Pro Power. We have parts for Detroit Diesel engines, Cummins engines and more. If you have any questions or need assistance, contact us today.