Mercruiser 140 head gasket blown?

[Nate Haught]

First time boat owner this year of an 86 galaxy admiral w an io 140 mercuiser alpha one. Had run fine except for minor issues all summer but max speed 35 w light load which I expected higher. Anyway started taking family out today and a mix of murkey oil and water suddenly started spurting out at the top of Motor splattering everywhere . Immediately turned back to dock. At home I drained oil and , checked dipstick and all full of water . Not sure yet if it's in cylinders will check that tomorrow . Think I'm looking at a head gasket? If so is it worth it for a $1500 boat?

 

[Nate Haught]

Edit misspell

 

[kenny nunez]

If the engine was still running and the power felt the same it is probably a hole in either the top of the head or a similar one in the lower crankcase area. Take off the valve cover and connect a garden hose to the where the drive pump connects to the thermostat housing and just let the water flow . Needless to say you do not run the engine for this to look for a leak. Hopefully it may just be a bad head. Usually when an engine fills with water like you mentioned it is not a head gasket leak.

 

[Scott Danforth]

could be head gasket, could be cracked block or head

best to pressurize the cooling jacket size and look for leaks.

as far as top speed with a 3.0, a light hull will get you 40mph above that you need more motor

 

[Nate Haught]

Thank you gentlemen

 

[Nate Haught]

So I took the valve cover off and noticed gasket was compromised in same area as leak which explains how the oil water was getting out. Pulled plugs and they are good no sign of moisture. I read some articles about the many ways that water can get in. One suggested a common issue is water coming back up through the exhaust after making a quick stop for example . Is it possible the water was already there ? Maybe I should try buying a valve cover gasket , change oil and put on muffs just to test for soundness before taking off heads ? I see no sign on top of valves of any gasket issue there. Thoughts?

 

[kenny nunez]

Drain the oil/water out of the engine leave the drain plug out. Perform the test like I described in post #3. If more water starts draining from the drain plug hole and nothing is showing on top of the head then the block is probably the reason . GM 4 cylinder engines have a few thin spots that are notorious for leaking into the oil. If the manifold was leaking you would have had water on the spark plugs.

 

[Bondo]

So I took the valve cover off and noticed gasket was compromised in same area as leak which explains how the oil water was getting out.

Ayuh,..... Welcome Aboard,.... I don't understand this quote,.....

There's No water, anywhere near the valve cover, nor it's gasket,.... Oil on 1 side, 'n outside on the other,....

 

[Nate Haught]

Thanks Kenny ! That test makes total sense, will try next day I have a chance on Wednesday

 

[Nate Haught]

Bondo my thought was that if the engine was filling up w water it blew out the valve gasket trying to get out .could have also spit out of the breather hose on top of valve cover . All the oil water was for sure coming out the top around valve cover. I know that's not how the water got in though. Just wishful thinking I guess th that somehow it got sucked through exhaust on a fluke . I've read that this does happen on io and can be a reason for water in oil . Basically I'm procrastinating ripping the head off I'll do Kennys water test and if it startts pouring out of drain hole no doubt it's head rippin time

 

[Nate Haught]

One more thing I forgot to mention. Doubt it has anything pertinent to this problem but... the boat struggled to start the day of the incident . Crank crank Thud! Crank crank Thud. One of the alternator wires - the orange won was loose. I turned it over and tried starting her for 5 minutes before I realized this. Hooked it back up and she started . Pulled out and minutes later I'm coming back with oil / water spewing everywhere . Prob nothing to do with it just a cluster of bad boat mojo .

 

[nola mike]

Unless you had water in your cylinder(s), which would cause that starting issue.

 

[Nate Haught]

Did Kennys hose test . Sure enough water came out the oil drain hole. Cracked blockville. Thanks for the help guys .