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Maybe the source of a "milky oil.'

WREKS

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I was trying to word it carefully, as "cooling water pressure when connected to a municipal water supply".
To my very simple mind stronger pisser stream indicates higher cooling water pressure in the system. That stream is always significantly "stronger" when running at WOT as compared to running on a hose.

Sorry, I forgot now the exact reason for those statements but in general I would think you have salt (aluminum oxide) build up in your cooling passages restricting cooling water circulation that over time created enough obstruction to cause secondary issues.
(Chemically speaking, most salt compounds are not water soluble, or barely, and do not taste like kitchen "salt", btw.)

--
That is probably the case. As a new owner, 12 years ago, more than just salt water entered the cooling system.

Thanks for the heads up on the salt. I will not season any vegetables with it.

Regarding the build up in the cylinder block water jackets: A lot of it was loose, collecting on both sides of the head gasket, which by the way is a series of small circular holes with 2 elongated holes on either end. The water jackets in the cylinder block were especially plugged around cylinder #1. I actually had to chisel out the build up using a small screw driver and various shaped pics. All of the cooling water for the cylinder block water jackets comes in the two hoses on the exhaust side of the cylinder block between cylinders #3 and #4 (closer to #4 and far from #1) . The flush path out of the cylinder block water jackets is up through the head gasket into the cylinder head and out through the cooling water pipe. That seems like a pretty tall order for any sediment that may enter the cooling system, whatever it's composition.

Incidentally, the bottom of the cylinder water jackets is where lot of the members have experienced cracked blocks. I wonder if there is any correlation?

I still do not know how this relates to "Milky oil." A leak-down test is next.
 
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WREKS

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Leakdown test results using 100 PSI reference:
cylinder #1 92 PSI
cylinder #2 89 PSI
cylinder #3 90 PSI
cylinder #4 94 PSI
 

haknslash

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FWIW I flushed my boat for close to 3 years at 70-75 PSI. I adjusted my regulator so that I could reach those levels so that I’d see water coming out the pissers while on the hose. Never had an issue with running higher water pressure.
 

WREKS

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FWIW I flushed my boat for close to 3 years at 70-75 PSI. I adjusted my regulator so that I could reach those levels so that I’d see water coming out the pissers while on the hose. Never had an issue with running higher water pressure.
Did your engines have the cooling water return pipe coming up through the valve cover?
 

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I had 1.8L so don't think so.
 

WREKS

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The cooling water pipes have been problematic, because they have an o-ring seal under the valve cover. That is my concern whether these seals can be over pressurized and allow water to mix with oil when flushing using 80 psi city water. Usually I use my irrigation pump which is 25 psi.
 

WREKS

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The leak down test I did was on a cold engine. On warm engine, cylinder #1 is 40 PSI. No air leaking through intake or exhaust valves or crankcase. Air loud and clear in water cooling passages. Must be leaking through that big corrosion gash in cylinder # 1. I hope it just a matter of getting head welded and resurfaced.
 

Gym

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The cooling water pipes have been problematic, because they have an o-ring seal under the valve cover. That is my concern whether these seals can be over pressurized and allow water to mix with oil when flushing using 80 psi city water. Usually I use my irrigation pump which is 25 psi.
I doubt that water pressure is an issue with a system as open as ours. If this were a closed loop system it would be a concern. Even with your 80psi hose pressure I don't think our open system sees more than 15psi. If your system saw even 40psi your pee holes would be squirting 50 feet out from the boat.
 

WREKS

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Yes. I think the issue is the corrosion canal in the head between cylinder # 1 combustion chamber and the closest cooling water passage (Post # 4 pic above).
 
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