www.boatdiesel.com is worth every penny. I am currently investigating the installation of a pyrometer on my Yanmar 6LP. I never heard of a pyrometer before boatdiesel.com. Here's a synopsis from Tony Athens, the guru of boatdiesel on fresh water flushing.
Response #1 from: Tony Athens [email] Forums Moderator Date: September 02, 2007 - 07:56 AM
Roy,
You need to search the archives as the "PRINCIPLE" of how to do it easily and safely are all there.. Stern drive or ?, does not matter--The idea to to "oversupply" what the engine needs at idle and NEVER shut the intake off. Excess goes out to the ocean.
I typed in "fresh water flush" and my name as author and came up with this post and some other threads on the subject.
There are about 8,700 hours in a year and when you consider that most recreational boats may be gone from the dock well less than 10% of that time, it should be pretty obvious where all the corrosion takes place. "It ain't at sea, it's at the dock.." Why leave salt water in the seawater circuit of the engine???
I've summarized a few postings below on this subject that are in the archives and easy to find w/ the search engine (key word "flush") Also, I've attached a couple of pics showing hook-ups (inside the folder)..
The top of a Groco type strainer is always easy for attaching the fresh water flush hose. Normally, I like to put the "T" between the strainer and the engine as this way, it not only feeds the engine, but back-flushes the strainer after the engine has shut off, as all the water is now passing backwards through the strainer through the bottom of the boat. One of the main things that needs to be done is to make it EASY to accomplish this task as most boat owners don't want to drag a hose into their cabin or engine room. We like to put fittings/attachments for the dock hose on the deck or cap rail for easy hook up. Just about all of the rec. repowers that we do end up with fresh water flushes....
Always leave the seacock open and IF the water flow from the dock is greater than the needs of the engine at an idle (usually is if a good valve/water flow/pressure is at the dock, you have a good hose and 5/8" or bigger plumbing all the way to the "T" in your system,) the engine will only have fresh water in it after a couple of minutes of idling.. Shut off the engine first and the fresh water will just go out the bottom of the boat, as the seacock is STILL open. Since fresh water is lighter than seawater, even after months with the seacock left open, you'll find fresh water still in the system..(I'm not keen on shutting seacocks as my memory is used up)......... I like to put the "T" in between the strainer and the engine pump as this way you are also back-flushing the strainer (a lot) when the engine is off..This type of hook-up requires a few extra fittings and is not always as easy to do.......If the owner makes the flush system easy to use (not having to drag a hose into the main salon) then this type of upgrade to a modern diesel will add years to the life of the entire seawater side of the engine (especially zincs, seawater cooled aftercoolers, etc).. One more little trick to basket strainer longevity is to cut up chunks of your old plate zinc and keep one or two of them in the bottom of your S.S. basket.....
Because the hose connects below the waterline in most cases and is part of the engines "vital" systems, always use high quality hose and fittings coupled w/ some good planning for the install.
Taking this another step in the direction of letting your engines have some time off, (winter, no fish around, vacation, etc), I'd rather let "my" engines sit unused in a warm/clean engine room with fresh water (or coolant in very cold climates) in the sea water circuit for months at a time before I'd go down and try to do a "dockside warm up." I believe in fresh water flushes, block heaters for all applications, regardless of the outside air temperature (I may use a thermostat, low wattage units, or timer in warmer climates) and I don't believe that letting an engine sit unused in the conditions I like to see an engine room detract from its overall life. For engines that I know or feel have not been run for many months/years, I will typically prelube the main oil gallery using one of various techniques. It's real typical in the commercial business I've been involved in to have boats in a fishery where there are 2 week to 6 week closures after 2 to 3 months of basically non-stop work. During the off time, nothing usually transpires besides boat maintenance and when it's time to go fishing again, all they do is turn the key and BANG. Hope[/size] this he[/size]lps .....................Tony
