Jabsco "Water Puppy Pump" - as emergency raw water pump

Greetings,
I have a question to offer for interesting responses. Some will recall or note that I made inquiry on raw water pump (Jabsco 11850-0701) recently. From the responses I have ordered the replacement pump (Sherwood H5) from sources given, Thanks for that. Let me add that the supplier has been most helpful and I am comfortable with the order. Whether or not the current pulley can be adapted remains to be seen, my son can adapt it or I order the after market pulley from this same supplier.
In the meanwhile, the thought came across the old brain that if in deed I lost the use of the current pump while all of this replacement effort is in play, could I adapt my 6 gpm Jabsco water puppy pump into the raw water system between the engine and the sea water filter unit? The question is if the water puppy has enough 'humph' to push the water through the engine to the exhaust outlet. Or, could one plumb the water puppy directly to the exhaust elbow and would the engine handle cooling without the raw water going through the exchanger? Any thoughts? I don't mind being yelled at if I am way off base.
Al Johnson
27' Marben
Ketchikan (Bridge to Nowhere) Alaska

This is sent with a lot of IFs in it because of not knowing your particular system...

In my experience the water puppy would be fine for emergency running or manuevering around a marina or two as long as you can regulate it so it is NOT running when the engine isn't so it doesn't back up and flood the cylinders (at least with many exhaust systems with mufflers).

I wouldn't bypass the heat exchanger.

You may get yelled at because some can never think outside the box and will say you are jeapordizing your engine, boat and life even...but that's them. You may BE jeopardizing your engine to some degree if you DON'T understand what you are doing (with some basic research) AND if you don't pay attention to the details while running it.

Many people have set up their cooling systems that stray from the manufactured design...so it is possible...just becareful.

Our raw water pump disintegrated about half way down the Exumas. I rigged the A/C pump to run off the inverter and used it to feed the engine. Worked fine till we got to Georgetown and ordered a new pump. As mentioned before, be sure to turn the pump off while the engine is not running to keep from flooding the cylinders.

Bob

Thanks fellows, Follow up on this. As the cooling system is a closed system self contained with anti-freeze/water mix. The raw water flows through the exchange system via tubes exiting out the exhaust elbow to cool the rubber exhaust hose. Is this not the case? If so, while it is understood shutting off the water puppy as you shut down the engine is correct in saving wear on the water puppy, would not the water continue to flow through the system and out the exhaust without access to the engine cylinders.

As I work on the principal that 'You have only the tools and items at hand in the middle of the Sahara Desert to work with, what can you do to escape the current disasterious situation' hearing positive response to the concept gives me some solitude as I await the new replacement pump. Understand, the current pump (Jabsco) is functioning as designed, just a nervous concern on my part as help in this part of the country can be wanting when needed!! I am sure most of you have read of Eric out of Thorne Bay with the 'Willie'. He travels in the same water(s) I do. Not friendly a great deal of the time.

No Boat USA around here.

Al Johnson
27 foot Marben
Ketchikan (Bridge to Nowhere) Alaska

Al said:

... would not the water continue to flow through the system and out the exhaust without access to the engine cylinders.

Click to expand...

Depending on your particular installation, no, that is not necessarily how it works.

When the engine is running, exhaust pressure helps to blow the cooling water out the exhaust piping. In the case of a waterlift type muffler, it is all that moves the water out of the canister.

If the engine is not running the likelihood of cooling water filling the vertical rise of the exhaust system is very high and that water will quickly flow into the nearest open exhaust valve directly into the cylinder and will just as quickly dampen your financial spirits.

Back again with a report.

The Sherwood pump arrived in today's mail. I have gathered all the required (I hope) plumbing pieces to make the change. In the meanwhile, I came across the local marine mechanic and ran the question by him. You guys and he are in accord. He mentioned the relationship between the exhaust elbow height and the waterline, if there were or not, a water lift muffler, and confirmed the information regarding exhaust valve allowing water in under the pressure of the continued running water puppy. What a good feeling to know the information found on this site has validity!
The mechanic went on to relate how a old cannery tender used a cast iron boiler circulating pump for years, why the salt water didn't destroy it he didn't say. And BobH- without any prompts, this mechanic, chuckled as he told of a visiting yacht arriving having used its A/C pump to make it here.
Small world for emergency repairs.
Thanks again for the response. (and nobody yelled!

Al johnson

>>>without any prompts, this mechanic, chuckled as he told of a visiting yacht arriving having used its A/C pump to make it here.<<<

And here I thought that was an original idea. I guess as the old saying goes, "there's nothing new under the sun".

Bob