Well it happened. Water in oil

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,071
My old beater boat finally went a bit south. I've always winterized it and serviced it properly. It's a 1983 Chapparral, and is my beater for the kids to run hard and pt away wet,lol. Mercruiser 120. I'm betting on headgasket issue myself. I need to pressure test the cooling system yet, and compression. Reguardless I have a good spare motor to bolt right in if need be. Happy boating people!
 

kenny nunez

Captain
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Jun 20, 2017
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3,290
Down at the bottom of the water jacket is the thinnest part of the block. That is usually where the it leaks at. If you flip it over and pull the pan you will see a rust spot where the hole is. Just as AD said you got your use out of it for 40 years. Quite a few never lasted that long.
 

Grub54891

Admiral
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Jun 17, 2012
Messages
6,071
yeah, old motor. Haven't seen one with the rust you mention Kenny but We will see what I come up with hopefully this weekend. It's still at the cabin in the water.
 

ScottinAZ

Master Chief Petty Officer
Joined
Jun 25, 2009
Messages
831
mine is a couple years older than yours (1980), and my water in the oil issue was the exhaust riser elbow rotted out, and it came in through the exhaust. Simple fix, if your manifold is still original, It may be somewhere to look, and isnt a catastrophic issue to change, just a PITA with the lower bellows boot.
 

Grub54891

Admiral
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Jun 17, 2012
Messages
6,071
Well,
i checked compression, cold and had 120 on all 4. Not the best but at least even across the board. Pressure checked the raw water side of the block and it held at 15 lbs for 10 minutes. I'll be checking the riser/exhaust side next. Also I ordered the exhaust flapper as it could be suspect. the kids were pulling tubes most of the day, and quick slowdowns could have ingested some if the flapper was bad. Skeeters were rather thick, so I quit for the day. Oil change and further checking in the works. If worst case comes up I do have a 140 to stuff in there.
 

ScottinAZ

Master Chief Petty Officer
Joined
Jun 25, 2009
Messages
831
Well,
i checked compression, cold and had 120 on all 4. Not the best but at least even across the board. Pressure checked the raw water side of the block and it held at 15 lbs for 10 minutes. I'll be checking the riser/exhaust side next. Also I ordered the exhaust flapper as it could be suspect. the kids were pulling tubes most of the day, and quick slowdowns could have ingested some if the flapper was bad. Skeeters were rather thick, so I quit for the day. Oil change and further checking in the works. If worst case comes up I do have a 140 to stuff in there.
well, if its not the block/heads your job is still a bit easier. Not that the exhaust side is "fun", but it sure is a bit lighter. You may be on to something with the bad flapper, although if yours is as big a PITA to access as mine, its a NO FUN job for sure to get the original rivets drilled out
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,428
Well,
i checked compression, cold and had 120 on all 4. Not the best but at least even across the board. Pressure checked the raw water side of the block and it held at 15 lbs for 10 minutes. I'll be checking the riser/exhaust side next. Also I ordered the exhaust flapper as it could be suspect. the kids were pulling tubes most of the day, and quick slowdowns could have ingested some if the flapper was bad. Skeeters were rather thick, so I quit for the day. Oil change and further checking in the works. If worst case comes up I do have a 140 to stuff in there.
Flapper is possible, but I had mine basically roached for years when I changed it and never got water back in. Would test the manifold with acetone to see if it leaks, or was that included in the pressure test?

Is it getting up to temp? Might be condensation if the thermostat is stuck open.

Would keep changing the oil until it is clear. you only need 3 qts in there to run at a fast idle and dump clearing it out
 

Grub54891

Admiral
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Jun 17, 2012
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I did not check the manifold yet. It’s getting up to temp better than before as I did change the thermostat this spring, 140* . I’ll change the oil, but when I do it I add sea foam to the mix and it helps the cleaning out a lot. When we get those at the marina that sank or such the sea foam goes a long way to get the water out without added/ multiple oil changes.
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,071
Well, I installed the new flapper, the old one was stiff but in place, wouldn’t close at all. Took it for half hour ride stopping from full throttle quickly and various speeds. Oil still clear. The real test next weekend on the 4th weekend when the kids run it hard and put it away wet! Lol. I think it’ll be ok. Anything changes and I’ll update.
 
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