Thru-Hull Flush Kit Thing-a-muh-bob

[Pegasus]

Hey gang,
I needed to run the Yanmar in the A-25 to check on a few things, being a new to me boat. I searched high and low for some kind of "flush kit" for a thru hull freshwater intake situation. I did not want to have to splash the boat at the local lake just to test run the motor so I came up with a simple little fresh water flush kit that will also be good to flush the salt water out of her after coaster cruising. I put it together with parts from the local hardware store. I'm sure someone else has already been down this road, but i figured I would share. It works great.

[DesertAlbin736]

I made up a similar hose rig, but on a slightly different principle. I don't have pictures of the rig, but what I did was take a 5 gallon plastic bucket that 3" chlorine tabs for my swimming pool come in, drilled a hole near the bottom of the bucket and hooked up a garden hose threaded on/off valve just like the one you used & attached a short length of 5/8" auto heater hose with a barb fitting on the opposite end. Then I set the bucket on the cockpit bench seat, remove the cap & strainer from the Vetus raw water strainer pictured below, plug the hose into the outlet side of the strainer (red hose). I fill the bucket with water using a garden hose with on/off spray nozzle. This allows a positive gravity "head" flow from the bucket to the raw water pump. I open the bucket valve & fire up the trusty Yanmar. The 5 gallon bucket gives about a minute of running time, so I just keep filling the bucket as needed for as long as I need to run the engine. That also tells me that the water pump is drawing from the bucket. Mostly that's running the engine long enough to warm up about once every month or two when the boat is sitting on the trailer & not being used. Our local boating venue is a fresh water lake, so in that case flushing salt water out of the system is not necessary. That way I don't risk raw water getting into the cylinders under pressure from the exhaust elbow . Any overflow goes into the bilge & easily pumped out.

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[Pegasus]

@DesertAlbin Nice set up. I like that version too. It's great to see all of the different ways people approach an "opportunity".

[WillieC]

I put a tee after and in line with seacock and thru hull. I also remove the outside bronze strainer/scoop. The top of the tee is normally capped. I remove it and hand tighten a fitting that adapts to a length of pex that reaches the five gallon bucket I place on the swim step into which I run a garden hose.

I usually assist-prime the pex hanging in the bucket by opening the seacock and spraying the garden hose directly into the pex. Then closing the seacock and submerging the pex back in the bucket. Be quick about it or lose the prime. If it’s difficult to understand, the Starfleet Commander feels your pain. Usually the raw water pump will pick up without priming.

I aligned all the fittings as described above so that I could easily rod out the intake in the event of a massive seaweed ingestion. You want to be quick about removing and replacing the cap on the tee while in the water. I have never had to do this maneuver, knock on fiberglass.

[Pegasus]

@willieC .. I may have to adopt a more permanent solution like you and Desert Albin in the long run. This was my first attempt at setting up something to be able to run through the systems in the driveway prior to splashing her. Now that I see how you guys have set up a "suction" type freshwater feed, I am second guessing my "forced feed" set up. I don't want to force water up into the engine in reverse, kinda like when you crank the engine over and over and it doesn't fire but can fill with water, if you know what I mean. I am stoked at the thought of getting her out there in cruising mode though.

[WillieC]

Def. The best thing is getting it in the water!

I was familiar with the muffs used on outboard engines but had no idea how to flush and/or test run the inboard on the hard. Was it even a thing? (Newby ignorance we had plenty.) So I thought about it and tried to imitate establishing the water line pickup level. I had no idea how much lift a vaned raw water pump could accomplish. I was so green, when I found ten or twenty year old replacement impellers in consignment shops for half price, I thought I had won the lottery! Wrong! (I now buy new every couple years and put the purchase date on the package. And I change them before they bust a vane...mostly. They last longer if you open the seacock after emergency replacement I have noticed.)

A slick trick I see that you can BUY, not invent, is a strainer cap fitted with a hose attachment. We have a Groco strainer with a screw cap (hand tighten only means HAND TIGHTEN ONLY). I could buy one, but I keep scrounging the consignment shops hoping to find one cheap I could put a hose fitting on. A device like this, adapted for your strainer, is also a great way to rinse the seawater side of your cooling system while out tooling around the Salish Sea. All you need is a bucket of fresh water. Dock hopping, you could do this every day.

It is amazing to me how many folks neglect their heat exchangers. I usually rinse a couple times a year, I tried Salt Away once, but you really don't know unless you open the HX. Besides you have to scrape the crud from the dissolved anodes out. This year I rigged up a bucket of Rydlime and a circulating pump and went nuts. I also installed a new SS exhaust elbow, hoping for eternal non-maintenance. Don't believe it. It all needs your attention, every year.

Oh, you'll figure it out. I know folks who, over the winter with the boat on its trailer, run their engines maybe once a month until it's "warm", thinking it will keep them up to snuff. I'm not so sure about that, having read articles about how idled/unloaded engines tend to cause more problems with diesel washing the tops of the cylinders leading to ring troubles. You can't get a diesel warm enough without at least an Italian Tuneup, apologies to my Italian friends. That process involves tying the boat up to a dock or pier, preferably in the water, not water adjacent. The transmission is engaged, rpms run up to not ruining the dock, the prop spins under load and the engine actually heats up as designed. It takes us fifteen minutes running time (away from the dock) under easy throttle until the thermostat opens, which I consider warmed up. It's that obvious on the temp gauge. Then it's pedal to the medal, ok 6.5 kts. around 1600-1700 depending on current direction.

With the bigazz flywheel on the MD17C Volvo Penta, it's easy to spin by hand, especially if you release the compression levers on the valve covers. Actually, with the old engine, it was always easy to spin by hand. Hmm... the Armstrong compression test. I do this every couple weeks over the winter just to move everything around in there, especially if I leave the impeller in the pump. I know it's optimistic, but I have the fuel stop/engine shutdown cable engaged even when cold. I think you might actually be able to start this engine by hand if warm if it has fuel. Careful.

[Pegasus]

Hey WillieC that is some great info. I have learned not to delay impeller maintenance for sure.

I am definitely up to speed on the "Italian Tune Up" method. I have a couple of the old school Mercedes diesels and that tune up method works wonders for them

I like the modified stainer top idea. Gonna have to look into that.

[tribologist]

This one from Moller works pretty good. Its tall enough to go to the ground. I loop the hose around it so when done I just pull the hose to get it out so I don't have to crawl in to that wet mess. https://defender.com/en_us/moeller-adju ... -099081-00

[LopezMike]

I strongly suggest staying away from any system that works too well. That is, if it doesn't leak, it will create too much pressure in your raw water piping. Many strainers don't handle positive pressure very well which puts water in your bilge (no big deal). On the other hand, it avoids a worse scenario which is to have a bunch of water backing up through the exhaust elbow into your engine!

I have an external thing somewhat like the one sold by Defender but I have taken some care not to have it seal to the hull too well.

I also have a T-fitting in the line between the sea cock and the strainer. This side arm of the T leads to a valve and thence to a hose that goes to the bilge so that in case of an emergency, I can close the sea cock, open this new valve and the engine is now pumping from the bilge. Not a great idea if your bilge is as full of odds and ends as mine is but it beats sinking.

All of this is old hat and has been done many times by others. Now to the point.

At the bilge end of this emergency hose is a female hose fitting. When I wish to run Caprice on the trailer, I hook my shore water hose to this bilge hose. I then open the sea cock. After turning on the shore water, I crack this new emergency bilge pumping valve until water is flowing out through the sea cock onto the ground from the raw water intake. So far, so good? Now I carefully start closing the sea cock until I judge that enough shore water is backing up into the strainer. It doesn't take much at all to keep your impeller happy and provide enough water to cool your engine at light loads.

If you wish, after your engine is running, you can close down a bit more on the sea cock and provide more cooling water to the engine. If the exhaust is making it's usual disgusting burping and vomiting sounds and throwing sooty water all over the flower bed, you have enough water.

Sorry that this has dragged out so long. It's past my bed time. Good night.

Mike

[WillieC]

You had me at burping and vomiting.

Great description. Yes, don't overwhelm the engine with city pressure. I run our system through a bucket letting the raw water pump think everything is normal. But I do make sure the suction hose is primed.

I recently saw, through the magic of internet mind meld where ads appear just by thinking, a
thing-a-muh-bob very much like the OP's design but with the added twist of an expanding paint roller handle (or boat hook) complete with, hopefully, unused toilet plunger and hose connection! Genius! I still wouldn't hook it up to city pressure.

[tribologist]

The plunger is a back pressure regulator. It limits the pressure to maybe 2-10” WC. The Moeller one would not even push water as high as the waterline level. I can open the strainer with plunger on at full flow and I cant see water in strainer so its a conservative test. If it prime with plunger, it will prime in water.

[WillieC]

So that’s why using a plunger on a terlet is a hit or miss deal!

[tribologist]

So that’s why using a plunger on a terlet is a hit or miss deal!

Its all about the applied force. Start about a foot above the water surface and go at it with all you have. The velocity will carry tge liquid down. Trust me!

[WillieC]

Now THAT'S funny!

[hetek]

I may be a bit late, but here goes...

I've seen a similar device advertised called a "Fake a Lake". I believe it was marketed towards the tournament ski boat crowd. Very similar with a plunger type rubber cup over the sea strainer but it had an extendable prop rod that would contact the ground to keep it in place.

I currently have the Groco strainer cap WillieC is hunting for. I've also built my own using a spare cap and a nylon thru-hull fitting and a dab of silicone. Don't remember the price difference between the two (build vs buy), maybe I just felt rich that that day and splurged.

Last, about pressurizing the raw water system... I try not to. I let the pumps do what they do best - pump. Rather than connecting a garden hose to the strainer directly and turning on the tap, I run a short hose from the strainer cap adapter to a 5 gallon bucket, full of water. I use the garden hose to replenish the water in the bucket as the raw water pump draws it down, at its own pace. A second set of eyes is helpful to prevent the bucket from draining or overflowing in case you get distracted.

And don't forget to burp and prime the raw water system. While swapping out the strainer caps I fill the open strainer with the garden hose. Water goes in and air burps out. On my engine the plumbing is all down hill to the raw water pump. Gravity is my friend.

Bonus: The bucket trick is also how I feed my engine antifreeze when winterizing. Warm the engine up with fresh water. Shut it down. Dump the water out of the bucket and fill with antifreeze. Start the engine and when it sucks down the 5 gallons, kill the engine. Job done!