yamaha t9.9 ots of water in oil

[imnoxpert]

I am new to iboats and equally new to outboard motors. I was given a 1997 yamaha t9.9 4 stroke with no indication re care and/ issues. I put it in a drum of water, gave it some fresh gas and hit the electric start. It started up immediately and runs smooth as can be. So i shut her down and decided to change the oil. The oil was creamy white and seemed way more than 28 ounces engine calls for. I let her drain for a few days, added 28 oz fresh oil, then ran her at idle for 10 minutes. I drained the oil, again milky white and thick, and almost 1/2 gallon drained out into pail. I was hoping fuel was mixing with the oil as fuel pump eady to remove and check. Fuel pump diaphragm intact so fuel not the issue. I doubt head gasket issue as engine runs beautifully. I read this engine does not have any thermostats so where is water coming from? I cant do a comp test as i dont have 10mm adapter for my testor, nor can i do a leak test as i do not have appropriate testor.one last thing engine has not been in salt water. Only hudson river
Any thoughts greatly appreciated

 

[raczekp1]

pull the head and change head gasket.
before instaling the gasket, the head must be checked and resurface at the maschine shop
during head gasket instal be careful with small oring at the botom-its sealing oil from water chanel

 

[imnoxpert]

Thx! Will pull head and hv it checked! Thx for tip re O ring! Will post results when Available...

 

[Captain Caveman]

You said oil, but are you talking about the engine oil or the oil in the gearcase (near the propeller)? In boat motors, it is a lot more common that the gearcase oil gets contaminated with water, turning it milky white. If that is the case, you likely have some bad seals in the gearcase that need to be replaced.

 

[imnoxpert]

I m referring to engine oil, not gearcase. I did a compression test today, 135 lbs in top cyl and only 85 in lower cyl. I pulled head and attaching 2 oics. First pic is head with gasket, 2nd pic is a blow up with crude arrow pointing at suspicious "notch" at 2 o'clock on bottom cyl. Water jacket has lots of corrision in that area. Dont know if this is normal looking head or not worth salvaging? I predume that will become evident once i clean it up and check if warped. Any thoughts anyone? Thanks!

 

[imnoxpert]

I started to clean up engine head and suspect area is corrosion. Also found 2 pinholes alongside the corrosion.New pic attached. I think head is toast. Anyone need a yamaha 9.9hp mooring?
Thanks for your help.

 

[Sea Rider]

You can always weld the notch, holes whatever, clean the whole combustion chamber, install new head gaskets and recuperate that motor. All 4 strokes tend to "Make Oil" that's increasing the oil level way high from the max oil level with water, If so, just add 3/4 of the max oil quantity the motor works with and change it periodically say each 100 worked hours.

Happy Boating

 

[raczekp1]

valves should be taken out and cleaned and refited. valve sleves should be checked if there is no play at sides. and its good to change valve seals.
any aluminium loose should be welded back and the head needs to be resurfaced at the maschine shop