Time for Confidence Stream to Appear

A conversation among Whalers
alanbc
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Joined: Wed Jun 30, 2021 10:37 pm

Time for Confidence Stream to Appear

Postby alanbc » Fri Jul 02, 2021 3:51 pm

How long after starting an outboard should it take for cooling water to appear at the confidence stream outlet?

BACK STORY: I purchased a 15-footerwith a 2010 Mercury 50-HP engine, my first powerboat in all my 60-years. I just lowered the engine into a big plastic tub of water with a hose over-filling the tub. I ensured the water inlet holes were fully submerged.

I turned the key, and engine started right up (as it had at the seller's house).

But no water came out of the back of the motor. I left it running for about 20 seconds and still no water. What DID come out was warm air, almost like exhaust.

I then shut it off and wrote this missive, with a bit of a sick feeling in my stomach.

MORE QUESTIONS

Did I simply not wait long enough?

Is some sort of "priming" required?

Or was the nice old guy I bought this from scamming me with his stories about how fabulous it was?

MORE BACK STORY

I actually felt sorry for him and paid full asking price, not even attempting to grind him down, something I'm pretty good at.

Thanks for any thoughts.

Alan

alanbc
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Joined: Wed Jun 30, 2021 10:37 pm

Re: Newbie outboard question

Postby alanbc » Fri Jul 02, 2021 4:11 pm

Followup. Too upset to wait, I attached a hose to some "earmuffs", the things usually used for cooling outboards on dry land, and installed them carefully.

Still no water.

So I took a chance and started the motor. Now I got water out of an outlet that I'd previously overlooked.

The hole I HAD expected water out of was in fact the exhaust. I expected the exhaust to come out under water; this motor could noisy.

Anyway, I stopped the motor, removed the earmuffs and restarted it, to see if it would suck water all on its own, without the pressurized hose.

To my GREAT relief, I still got a confidence stream.

So, whether I didn't wait long enough, or I needed to prime it, I dunno.

But now I'll leave it for a day and see what happens tomorrow. Because if priming IS required, that's obviously a problem.

Don SSDD
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Location: Nova Scotia

Re: Newbie outboard question

Postby Don SSDD » Sat Jul 03, 2021 6:19 am

Priming not required, you just need the water intake screens submerged or tightly covered by the muffs. Submerged is best. On startup it can take a minute or so [for the cooling system to fill and for water to appear at the confidence outlet] if the boat has been out of the water for a while.

After running a bit, the water coming out should warm up once the thermostat opens. Will you maintain this outboard yourself, if yes, get the Mercury factory service manual for it, way better than the generic aftermarket manuals. Also check all the rubber fuel lines, bulb, tank for dirt, and pull the spark plugs to see condition. Use ethanol free fuel if you can access it.
1986 Outrage 18 with 2001 Honda 130 HP
Former Owner 1991 Guardian 19 with 1994 Evinrude V4 140HP
Former owner 1987 Montauk with 1998 Mercury 90HP
Nova Scotia

jimh
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Re: Time for Confidence Stream to Appear

Postby jimh » Sat Jul 03, 2021 8:32 am

Generally all outboard engines have a confidence stream output from the cooling system that confirms to the user the water pump is operating and there is a flow of water through the cooling passages. There usually is an orifice or nozzle that limits the flow of water being diverted to this outlet.

The time needed after engine start for water to appear at the confidence stream outlet varies depending on where in the cooling system the confidence stream outlet is located. On some engines the confidence stream outlet is very near the water pump, so the stream appears very soon after engine start, in just a few seconds.

On other engines the confidence stream outlet is much farther down the path of cooling water, and most of the water jacket in the engine block has to fill first before water appears at the confidence stream. This might take a minute to occur on a large displacement engine with a large volume of water in its cooling system.

The location also affects the temperature of the water coming out at the confidence stream outlet.

Outboard engines try to push their exhaust out under water, usually through an opening in the propeller hub. But at idle speed the back pressure for the through-hub exhaust is too high for the engine to overcome, and an alternative exhaust port, called the engine idle exhaust bypass, will provide an exhaust path above water.

Again, you need to buy a good book about about outboard engines and read it. The forum is here to help with Boston Whaler boats—and mostly older Boston Whaler boat.

The basics of how outboard engines work is not a focus here.

jimh
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Re: Time for Confidence Stream to Appear

Postby jimh » Sat Jul 03, 2021 8:59 am

Read the owner’s manual or operating guide for this outboard engine. The operating guide should explain basic procedures such as properly running the engine from a hose adapter.

The operating guide should also provide contact information to reach the manufacturer for help to explain features of the engine not well documented in the literature.

roundle1979
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Re: Time for Confidence Stream to Appear

Postby roundle1979 » Sat Jul 03, 2021 1:50 pm

Have you inspected the impeller [in the centrifugal water pump in the engine gear case housing]?

I change [the impeller in the water pump on an unidentified engine] every other season or [at run time intervals of] 100 hours.
2004 Nantucket 190 w/ Mercury Optimax 135

jimh
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Re: Time for Confidence Stream to Appear

Postby jimh » Sun Jul 04, 2021 6:56 am

Read the owner’s guide for the particular outboard engine to find the recommendation of the manufacturer for the service intervals at which the engine water pump impeller should be replaced.

Do not attempt to service the water pump until you have obtained the factory instructions and an OEM water pump service kit which will include the necessary additional components needed for proper service.

Use of poor procedures in servicing the pump and use of aftermarket replacement parts can easily cause more harm than good.

jimh
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Re: Time for Confidence Stream to Appear

Postby jimh » Mon Jul 05, 2021 6:31 pm

roundle1979 wrote:Have you inspected the impeller [in the centrifugal water pump in the engine gear case housing]?


Please describe the exact visual cues that a careful inspection of a centrifugal water pump impeller that will indicate it should be replaced. The thread initiator remarks he has no experience with outboard engines, so a recommendation to “inspect the impeller” should be accompanied by what to look for.

A corollary question: in your many visual checks on the water pump impeller, have you ever re-installed the existing impeller after inspecting it?

fno
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Re: Time for Confidence Stream to Appear

Postby fno » Tue Jul 06, 2021 6:17 pm

Given the amount of time and effort that goes into getting to the water pump impeller to inspect it and then put the whole thing back together, a sensible person would use that time and effort to just replace the impeller. One impeller every two or three years is a small price to pay for the enjoyment received.

jimh
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Re: Time for Confidence Stream to Appear

Postby jimh » Wed Jul 07, 2021 8:09 am

Frank—I agree with you. I never heard of just tearing down the lower unit to “inspect the impeller.” Once you disassemble the water pump, putting it back in place with all the old components would make no sense at all.

But I don’t think the advice to tear down the lower unit and disassemble the water pump to “inspect the impeller” is really the best answer to how long an interval should be considered normal between engine start and appearance of the confidence stream.

A perfectly normal water pump will still produce a delay between engine start and onset of flow from confidence stream, so the delay is not to be interpreted as a sign that the water pump needs service—the delay may be completely normal in engines with the confidence stream located at the end of a lengthy and high-volume water cooling jacket.

fno
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Re: Time for Confidence Stream to Appear

Postby fno » Wed Jul 07, 2021 8:27 am

A good point Jimh. Another thing to note is that many confidence streams do not "stream" much if any water when running at idle speeds which is typical at startup.