Fresh Water Flush

[mvweebles]

Weebles, I believe a blanket statement that pressurized shore water rinse is not for vessels with lift mufflers should be taken with a very large grain of salt because conducting a fresh water engine rinse this way is all about method and technique. I have been doing this for seven years now with my Yanmar 6LPA-STP 315 HP engine with lift muffler, and two things I do not do are to shut off the seacock and leave the water pressurized when the engine is not running. As evidenced by the excess water running out of the seacock (boat is in a lift) with the engine idling and taking the water it needs to cool via the seawater pump, there is MORE than enough volume in the ordinary shore water connection to cool and rinse the engine without necessitating seacock closure. I shut off the freshwater supply to the engine as I am pressing the engine shutdown button. If your setup does not allow for these simultaneous actions, either don't freshwater rinse or arrange things so you can. Besides the obvious forgetfulness that could result in an seacock left closed, I am concerned about over pressurizing the seawater pump's water seal resulting in a leak there requiring pump repair.

Rich - only echoing guidance from the video.

If there is a high point in the exhaust above the engine manifold (common with lift mufflers), there is risk of flooding the engine if you don't take suitable precautions such as those you outline. I am less concerned about forgetting to open the raw water intake than someone leaving the pressurized hose on without engine running, potentially forcing water past the impellor and flooding the exhaust and then engine. In the diagram on the SBMAR webpage, that cant happen. In the video, a lift-muffler diagram is shown and clearly it can happen which is why they caution against.

Running engine with closed seacock will most likely trigger an overheat alarm before damage. Flooding the engine is a problem, especially if you don't know it until you return to the boat.

Peter

 

[rgano]

Rich - only echoing guidance from the video. If there is a high point in the exhaust above the engine manifold, there is risk of flooding the engine if you don't take suitable precautions. I am less concerned about forgetting to open the raw water intake than someone leaving the pressurized hose on without engine running, potentially forcing water past the impellor and flooding the exhaust and then engine. Running engine with closed seacock will most likely trigger an overheat alarm before damage. Flooding the engine is a problem, especially if you don't know it until you return to the boat.

Peter

You are exactly right, Peter. Proper precautions.....

 

[Steve DAntonio]

To be clear, no fresh water flush system should be used on a non-running engine.

I can't say it's impossible, but I can't imagine any fresh water flush, regardless of exhaust system design, could lead to engine flooding if it's used only while the engine is running. The exhaust gasses are always expelling the water. I've set up many fresh water flush systems, and I have many clients who use them, I've never had this happen and I've never heard of it happening. Has anyone seen this first hand?

When winterizing engines, and I've done my share of that, I would let the engine draw from a fitting on the bottom of a 5 gal bucket, while letting the garden hose run into the bucket, or even into an open strainer. I did this so I could, after a flush, add anti-freeze to the system by simply pouring it into the bucker (or strainer). With that approach you never could force water into the engine, even if it wasn't running.

For any of these flush approaches, the seacock must be closed. When ever I do that, I tag the helm.

 

[Comodave]

You can use a SeaFlush adapter in the strainer with the basket removed. SeaFlush comes with a suction hose that you can stick into a bucket of plain water or antifreeze depending on the purpose of the flush. No pressurized water goes into the engine and it is simple to hook up. You do need some open room above the strainer though.

 

[rslifkin]

For any of these flush approaches, the seacock must be closed. When ever I do that, I tag the helm.

The tag is a good idea. And if there's a breaker supplying power to the key switch, trip it so the engine can't be cranked without resetting the breaker first. In my case, the ignition breakers are in the engine room (although reachable by opening the hatch and reaching down), so it pretty much forces you to notice why it was tripped, even if a note at the helm was missed.

 

[Portage_Bay]

Here's a new to me idea I just heard about from a good mechanic. Engine flush with Salt-Away. Anyone with experience flushing with Salt-Away? Worth the expense and effort?

 

[Bmarler]

Here's a new to me idea I just heard about from a good mechanic. Engine flush with Salt-Away. Anyone with experience flushing with Salt-Away? Worth the expense and effort?

It works. I had a friend that used salt away on his raw cooled engine. Definitely helped keep the passages open.
He just sucked it out of a bucket though.