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2003 Johnson 40 4 stroke-milky oil

LobbiJ

LobbiJ

New member
Hey guys, its been a while.

I have a new to me 2003 Johnson 40hp 4 stroke , 3 cylinder. EFI.
Checked the engine oil level before taking it out this spring, full and clean.

I have about 10 hours of trolling lake Michigan on it now. My new oil and filter arrived today so I'm changing it.
Haven't started the engine in the past 3 days- the Oil drained out looking like Creamed Coffee! And it was over full on the dip stick.

In my experience- Milky oil has a water intrusion problem. I'm aware of the damage this can cause.

I've done a (cold engine) compression check and have a solid 160 PSI on all 3 cylinders- like exactly 160 on all 3 cylinders.

Outside of a compression check I do not know how to diagnose where my leak is.
The strange part to me is that when I started draining the oil it was immediately milky- like the water and oil had not separated after 3 days of not having been run.

Any suggestions may be helpful.
 
I don't know what oil Was in it , I put Quicksilver 4 stroke oil in it today with an OEM filter so I could do the compression test.
The engine purrs like a kitten.
I have no history with the thermostat, I plan to pull it, heat it up on the stove with a thermometer in the water to know the temperature it opens at ..., If it's not already Open when I pull it out tomorrow.
 
The Oil filter I took off was Dated (5/23) , I can only assume that the last time the oil had been changed was in May 2023..
I did a Google search ..

"If a 4 stroke outboard engine oil has not been changed in a long time will it become milky"

Here's what came up..
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Well , I couldn't "Leave it alone" until tomorrow.
I took the thermostat housing off and I can see Immediately that it is stuck Wide Open.
It's anybody's guess how long This condition has existed.
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