2000 F100TLRY water in engine oil

[groveboy]

This engine has only 175 hours, bought 1 year ago from my uncle. Had mechanic rebuild 4 carbs and replaced water pump impeller. I changed Engine oil, looked fine, no water.
I've used motor about 5 times,10 hours.
Hadn't used motor in 2 months so I checked oil prior to running in driveway and it is white/cream color.
Drained oil, changed filter and ran with hose water to put new oil through motor. New oil also has water but I kinda expected it, not sure if its new water or existing water/oil. Engine starts easily, idles a little rough.
Removed spark plugs, #1 has brown colored buildup, #2 slight black, #3&4 very little buildup/discoloration. I have pics of plugs. Trying to get compression tester to perform test. Ordered Yahama service manual.
Asked around and was told don't waste time/money and some say head gasket failure.
I know this motor is 16 yrs. old but it has very low hours and looks showroom clean.
Can water contaminate oil if water pump replacement damaged something?
THANKS for any guidance.

[rodbolt17]

water pump is not your issue.
fuggit about it.

could you have a head gasket/head surface failure?
yep.
will a compression test find it?
nope.
use a leak down test.

you could also have an oil pan gasket failure.

[groveboy]

THANKS FOR REPLY
Could a oil pump seal failure cause water in oil?
Leak down test will be performed. Should I dismantle stuff before test so I can identify leak area: intake manifold, or other?
Where do I check to identify leak?

[groveboy]

Can I remove cylinder head without pulling entire powerhead from casing?

[groveboy]

Investigating how/why water is in engine oil?

Removed thermostat - crusty and stuck open. Purchased new and installed.
Removed contaminated oil and put new oil, ran engine for 5-10 mins. prior to performing both test but didn't input water when warming engine.

2000 Yama F100TLRY/4cyl,/4 carb results:
Compression test (psig) - #1 thru #4 = 210/215 psig - Yamaha specs min. pressure = 135 psig. Engine was warmed before this test.
Leak test (loss %) - #1 - 2%, #2 - 4%, #3 - 1%, #4 - 2% - engine wasn't as warm before test.
Could hear air leaking from oil fill cap hole/dip stick. None from exhaust, minor from intake air chamber.
These test results look very good to me. Glad about that but no indication from test of water/oil problem?

[99yam40]

a stuck open stat will cause a motor to run too cold. Not sure if being that cold would cause more water to condensate in the oil, but I have read it will cause fuel to dilute the oil.

You should not run an outboard with out water to it , the rubber water pump impeller will melt down due to friction without the water to lubricate and cool it and trash the plastic housing

[RayBersch]

"99Yam40: You should not run an outboard with out water to it , the rubber water pump impeller will melt down due to friction without the water to lubricate and cool it and trash the plastic housing."

99Yam, perhaps you should be more direct: Son, if you ran your motor for 5 to 10 min without water as you seem to imply, your entire water pump assembly is trash and you should not run your motor again until it is replaced.

Of course, you may have enough water pressure from your hose to actually circulate sufficient water through the motor to prevent over heating but you will have a rude awakening when next you launch your boat. End of story.

Ray

[groveboy]

thanks for all replies......
I will definitely investigate water pump issue, thanks.

I did run engine again with water and noticed that I have blow back out of oil fill and dip stick opening.
Seems like more than normal but not really sure due to never checking/noticing this before.

Any comments on compression and leakdown test results I posted above?

[rodbolt17]

numbers all looked good.
there will always be blowby in the crankcase vent line.
start the engine with the oil dipstick out and you will have an oil fountain.
leave the fill cap off and it will remove all the oil from the crankcase in an hour or so.
that motor has NO positive crankcase vent system.

[groveboy]

UPDATE: Removed powerhead and cylinder head. Small area corroded at bottom of head (below #4 piston) on water chamber wall and adjacent gasket surface. It wasn't very obvious, noticed discolor but gasket surface was smooth/flat. Used fingernail to pick at it and was able to remove corrosion, didn't expect that to happen. Head gasket and block at the corroded area looks perfect? All 3 anodes looked like new? Corroded water chamber area was partially plugged with deposits. Appears to be under deposit corrosion due to low flow/blockage. I have pics to post if y'all would like. THANKS

[TownsendsFJR1300]

Thanks for the update. Glad you found it.

Its not unusual for salt to build up in the block(and water passages-causing overheating too), especially if NOT FLUSHED religiously with fresh water.

Sounds like that's what caused your issue. Anodes won't prevent salt water dry/crust up in the passages corrode aluminum...

Couldn't get the head off without pulling the power head??

[99yam40]

Pictures are always interesting to see