Whats the best way to clean out an engine where water mixed with oil

JK Turtle

Cadet
Joined
May 18, 2013
Messages
26
So yesterday I was cleaning my boat and decided to check the oil and noticed the infamous brown milky oil. Originally I thought the block was cracked, but was hoping for something better. I did the pressure test in the cooling system and it would not keep pressure. I started to tear the engine apart, pulled the manifold off and checked the block but could not find any cracks, looked at the manifold and found about a 2" crack right in the middle. Thankfully its not the block. I don't do the full winterize because I use my boat year round, but I did drain the water out before a hard freeze came, but I'm at a new house and the driveway has a slight slope to it so I'm guessing with the jack fulling extended, some water was still able to stay in the manifold to crack it. I went fishing about a week ago, I checked the oil before I left and it looked good, boat ran good for the little bit of time I was on the lake. But now they engine is pretty gunked up. I ran that gunk motor flush for about 5 minutes before I tore the engine apart to get some of the gunk out, but there is still a lot in there. I'm thinking about spray some cleaner on the parts I can see under the manifold, then taking the valve covers off and spraying those as well. Any ideas if this will be a good idea, or any other way?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,234
drain oil
put in fresh oil
run motor at temp - HARD for a long period of time, like an hour or so at 4000 RPM
check again.

the heat of running the motor evaporates the water
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,082
Ayuh,.... Agreed,.... Steam it out the vents by Runnin' it,....
 

charleso

Petty Officer 2nd Class
Joined
Nov 13, 2006
Messages
179
You can put diesel fuel or kerosene in the oil. Run the engine AT IDLE ONLY. Drain completely. Refill with clean oil and add Seafoam. Then run it again, drain again. Keep watching for signs of water. May have to change the oil several times to completely clear it.
 

Hoosmatroos

Petty Officer 1st Class
Joined
Jul 11, 2011
Messages
250
When repairing submerged outboards I'll allways drain and fill with some cheaper oil. Run it for a while, let it warm up properly, and drain again. After that put in normal oil and run it as normal.

For an inboard do the same , 1 more time extra oil to get the most water out is the best way. After that run it for longer time with higer RPM's to evaporate the left moisture.
 

crazy charlie

Vice Admiral
Joined
May 22, 2003
Messages
5,581
Do an oil change and replace 1 quart of the fresh oil with either MMO or Trans fluid or Seafoam.Let motor idle for an extended period to make sure engine is fully warmed thus getting any steam.moisture residue out of the motor.That should work for you.If you can get to the oil pan drain with no problems,I would start there getting every drop of contaminated oil out of the pan before you start.Charlie
 

savetexomabeaches

Chief Petty Officer
Joined
Jul 4, 2013
Messages
420
Do oil change with cheap oil and pour half a bottle of seafoam in the crankcase, run the heck out of it, while its at temp, shut er down and do an oil change.
 

2fishy4u

Petty Officer 3rd Class
Joined
Aug 3, 2015
Messages
85
When I had this issue I did what Scott and Bondo said. I did change the oil a couple times though, only because I could not pull the drain plug. I had to syphon through the did stick tube. But after running it for an hour it stopped steaming and have had no issues for the last 75 engine hours.
 
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