Running engine on trailer...water intake question

H

harley

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Joined
Oct 10, 2020
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100
Fluid Motion Model
C-24 C
My 21 EC is the first trailerable inboard I have owned. Can you run the motor on the trailer with a water hose connected to the fitting for adding antifreeze next to the intake water strainer? My boat has a small garden hose fitting marked "prestone" next to the intake, used for adding antifreeze for winterizing I imagine.

I bought one of those plunger things you put over the main intake in the hull for accomplishing this, but the way the boat is sitting on the trailer, the structure of the trailer blocks access to the intake thru hull. (Something to watch out for next time I positing boat on the trailer.

Would I close the intake thru hull, connect a garden hose from the house to the fitting and run water through engine that way and be ok? I need to do some tests on the motor, my new engine control panel, new oil and water sending units and hopefully warm up things enough to change the oil.

Thank you for your advice,
Harley
 
The Prestone fitting you mention is used to draw antifreeze into the block for winterizing. When I say draw, I use a short hose with garden hose fitting into a 5 gallon bucket in the cockpit filled with antifreeze.. The engine draws the fluid at its own pace.

You could run the engine in the same manner by feeding water to the bucket with a hose. The engine would draw water as needed.

Hooking a hose directly and forcing water under pressure wou.d risk hydro locking the engine. It needs to draw at its own pace. Do not pressure feed directly.
 
Previous post is correct about possible hydro lock. However if you leave the sea cock open you should be okay. I usually will close the seacock open the strainer and let the garden hose run into the strainer while letting it overflow into the bilge.
 
I agree with Mike, but in addition, I take out the garboard plug that will completely empty the bilge. Between the bilge pump and garboard plug no danger of rising waters. A nice trick is to regulate water flow into the water strainer so that it just overflows into the bilge. This can be done with a faucet attached between a three-foot extension that reaches into the open strainer. Make sure this extension is securely attached into the strainer--so it does not slip out--otherwise, you will be changing the impellor should the hose slip out of the strainer.
 
On 21ec tugs, using the Prestone fitting and bucket routine is preferred as the sea water strainer is usually the small Jabsco unit and is side mounted .

The larger tugs use significantly larger top loading units that allow for the flooding technique mentioned above.
 
Thank you for all these options...I need to run it till warm....sounds like the best way is figure out how to feed the thru hull intake with my Fake a Lake adapter....but then that is forcing pressured water in that intake...
Isn't that what is normally done?

Harley
 
Harley, I close the hull intake, remove the cap that says Preston (notice it is a male fitting) and attach a jumper hose about 3 ft long (a old wash machine hose works great as both ends are female) place a 5 gal bucket next to it and fill with water. Keep water hose available with shut off on end to keep the bucket with enough water. This is the same procedure to winterize, just place end of hose in gal of RV antifreeze. You can run engine all day this way with no chance of hydro locking the engine! If you want to know what happens when you hydro lock the engine I can give you a phone number of someone that's has done it. Best of luck Bob
 
Hey Bob....those of us that need to winterize. Know the 5 gal bucket ritual eh....?.....

Hydrolock = $$$$$$$$$$$$$

Happy Thanksgiving. ...............
 
How do you know it is hydrolocked? I did run the motor for a bit with the Fake a Lake just to see if my new panel and oil pressure sender worked. They did...then I shut down...I was getting decent water out the exhaust but so much leaked around the intake that I need to make sure I have it fully secured to run it long enough to warm the engine to change oil and test new water temp gauge.

I will likely try the recirculating barrel approach. That way you can see exactly what is going on.
 
You will know if it's hydro locked when engine stops and when you try to re-start you damage the starter motor due to the motor not turning over. You will have to remove the injectors and glow plugs and turn motor over by hand to remove water from cylinders. Drain oil and replace filter a few times till oil is clean and no water detected. Thank GOD that the Yanmar 3Ym30 is a tough little engine, my brother went through this on his 1993 R-21 a few years ago. Bob
 
I had that twice on my sailboat Volvos and both times it was failed exhaust elbows. Saved engine both times by doing the procedure mentioned. Just did not know that was called hydro locking I just thought it was water in my engine. My latest Volvo D1-30 had custom stainless elbow made fir it to add longevity to that part.

Why would a Fake a Lake cause that? Water pressure or running water before engine running which fills up the system?

Harley
 
Harley, there has been much talk about hydro locking engines on this site, most of the time it happens when being towed with the sea cock open and water is forced in to the system and overtaking the impeller on the sea water pump. Yes a fouled exhaust elbow will add to the chances of water entering the engine. Lots of owners can get away with being towed with sea water valve open or running the engine with a garden hose hooked up as you described. But why take the chance? Remember BOB's rule, If it can go wrong, it WILL. Bob
 
Question - Prestone fitting???
You mean the water intake fitting starboard side of engine just after water strainer - correct?
Mine is just a blue cap so where does prestone come in?
 
Take a look around your local auto parts store or auto se tion of the big box and you will find the common Prestone Flush and Fill kits that contain these fittings in multiple hose sizes.

Boats that did not come equipped with such fittings use this kit........and some that have lost their "blue caps" find Prestone caps fit...............voila...........Prestone fitting......
 
I just take the cap off my strainer and put the hose directly into the strainer. I added a thumb valve on the end of the hose to regulate the flow of water so it matches what my engine is pulling. It keeps it from overflowing from the strainer, though if it did, it would just flow into the bilge.

I add antifreeze the same way, through the strainer. Once I see it coming out of the exhaust, I turn off the engine. Takes a little over 1 gallon.

Oh, I close the seacock first. It’s under the round hatch in front of the engine.
 
I ran just a minute with the Fake a Lake and it was fine. Water came out the exhaust for a few minutes and then stopped. I shut down immediately. I then tried a hose from water bucket into the fitting near the raw water strainer (shutting the thru hull intake for raw water) and nothing was drawn from my five gallon bucket in the first 30-seconds to a minute so I shut it down. I checked raw water impeller and half of one vane was broken off and gone. All other vanes look good. Knowing that piece of rubber can jam things down the line, I opened up the hoses going in and out of the heat exchanger and had no resistance to blowing air in hoses. I did the same all the way back to the output of the raw water pump and no resistance. I did the same after the heat exchanger and going into the exhaust elbow...no resistance.

So I am assuming the little piece of rubber is not blocking much or it already went through the system. No telling how long it has been off as this is the first time I opened the pump since I owned it. I have not had the boat in the water yet. Hoping for next week.

I will replace impeller when I can get one this coming week and will buy a few to have on hand for next time. I have not run dry for more than a few seconds so far and no telling what the previous owner did, but he did say he forgot to open the intake once. During the sea trial motor ran great with no issues and no overheating.
 
Harley, when I put my boat on the trailer I leave the hull valve open, this drains the water from the raw water pump to the hull fitting. When running on trailer with bucket, the pump has lost its prime!
I just rev up the engine and within a few seconds it will start to discharge water. To rev the engine without placing in gear, you push the center of the shifter lever prior to placing in forward position.
Depending on outside temperature you can run your engine for quite awhile be for the thermostat opens and calls for coolant! So don't worry if it takes a minute or two to prime the pump, all is good!
Bob
 
bob daily":cwyjmn55 said:
Harley, when I put my boat on the trailer I leave the hull valve open, this drains the water from the raw water pump to the hull fitting. When running on trailer with bucket, the pump has lost its prime!
I just rev up the engine and within a few seconds it will start to discharge water. To rev the engine without placing in gear, you push the center of the shifter lever prior to placing in forward position.
Depending on outside temperature you can run your engine for quite awhile be for the thermostat opens and calls for coolant! So don't worry if it takes a minute or two to prime the pump, all is good!
Bob
Click to expand...

Bob,
I am glad to hear your experience on this. I shut it down pretty quick when I did not see water going through and I was just at idle. Are you saying there will be no damage to the impeller letting the pump run without water as I thought it did not take long to ruin an impeller in the raw water pump if it is turning while dry. The pump will be turning as soon as the engine is running.

I have been searching priming issues since you mentioned this . Sounds common on the Yanmar 3YM30 and could be an air leak. I will recheck everything and really lube up the new impeller. I may go back to the Fake a Lake instead of the hose from the bucket. I think I will pull the cap from the antifreeze filler next to the strainer to see if I am getting water to flow that far from the intake thru-hull from the Fake a Lake to see if that system is working correctly and then recap and start engine. I never had this issue with my sailboat of 37 years, but the water intake strainer was a little above the pump and that probably helped. In this system the pump is just about the highest point.

Harley
 
Local Yanmar authorized service location suggested using garden hose from regular pressurized source into the system and leave the raw water thru hull OPEN when you start engine till prime achieved in the raw water pump, then you can shut that valve so there is no danger of hydrolock. I was wondering if I could just leave the hose leading into the exhaust elbow off, keeping water out of the exhaust elbow until primed. Then reconnect so I can confirm I see water going through system.

I pulled that hose at the outlet of the heat exchanger off already to back flow water through heat exchanger in hopes of finding the lost broken off vane from the impeller...sure enough it shot right of the open raw water pump housing. All pieces located so no chance of clog.

Harley
 
Harley, Glad you found all the pieces to the old propeller. As Grandma used to say there is more than one way to skin a cat, what ever works for you! I like to use the KISS theory when performing routine maintenance as I've said before if it can go wrong it will with me. Good luck Bob
 
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