Fresh water flushing

[nonitoo]

Being a bit careful with my boat and engine I note that the maintenance book says that the engine should be flushed with fresh water after every use.

How is this possible if the boat is marina based ? Do others perform this task after each use, if so, how do you do it as my outdrive water intake is always below the surface even when raised.

Do I just sit and watch it rot away ?

(Cummins Mercruiser 2.8 ltr diesel with Bravo 3 outdrive)

 

[ccscott49]

It should not rot away if you have anodes, look at all the other boats, do there engines rot away? Do they fresh water flush theres?

 

[gjgm]

might be a book common to several engines, but in your case, I dont think you can. I m pretty sure you ll have a seperate system around the block for cooling, and the sea water then cools that, so the two remain seperate. Its when sea water cools the block itself that flushing is a good idea.

 

[nonitoo]

No, you are absolutely correct of course.

The raw water passes through the engine block heat exchanger, fuel cooler, oil cooler, turbo intercooler, power steering cooler and exhaust water jacket.

The closed cooling passes through the engine block, turbocharger, exhaust manifold, domestic water heater and block heat exchanger.

I suppose I am just being paranoid, I was only worried at possible scaling in the raw water cooled bits.

 

[peterb26]

I had problems with a Sabre 300 TI about 6 years ago - mild overheating at higher revs.

The local Sabre chap (Terry at Selsey) took the intercooler back to his workshop and cleaned it. He said it was totally furred up, and this sorted the problem completely.

This happened in a year when I was hellish busy - and there were often periods of several weeks when the boat was unused on the mooring.

Terry's view was that if the boat was being left for anything more than perhaps a couple of weeks, then it paid dividends to close the seacocks and run a solution of tap water/antifreeze through the raw water system before leaving the boat.

He's a first class engineer so I suspect its good advice if you are away for a month or more.

 

[nonitoo]

I can understand that.

If I want to flush the engine I suppose I will have to somehow attach a freshwater coupling on the engine side of the sea inlet valve. The existing sea water inlet pipe is very stoutly constructed so this will not be easy (For me anyway).

 

[SilverTT]

At the end of the season i take off the water inlet & run anti freeze mix with water through engine. That is if i'm taking it out for winter.
Fresh water flushing is a great idea on outboard motors. I do this for my o/board on the tender. Save's the salt drying and blocking the waterways.

 

[peterb26]

Nonitoo - cant you just take the lid off the sea water filter and pour it in there?

 

[nonitoo]

That is certainly a possibility and I imagine that, as long as I keep the engine at idle, there would be sufficient water flow to stop the engine overheating.

I might give it a try.

 

[peterb26]

Thats exactly right Nonitoo - you'll find that you can pour it in quite fast enough at tickover.

 

[nonitoo]

Thanks Old Salt,

Much appreciated.

Tom

 

[peterb26]

Thats what the forum is all about Nonitoo. Happy to help - and Ive also received loads of help too.