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  1. #1

    Default Water in oil mystery?

    So I went for a cruise and everything ran perfect. I have twin Mercs inboards. I have an older boat and the engines are in the aft cabin with Vdrives.

    I went down to the marina to do my normal once a week run my engines and my starboard would not start or turn over. I immediately thought battery or starter. The starter was already a bit weak but got a slow turn then nothing. Both were fine so I checked the oil and the engine was full of water nearly to the top of the dipstick. It had been sitting all week. We did have a major rain storm and the aft cabin can leak depending on the winds and there was a lot of that. I assumed the rain filled through the leak hitting the flame arrestor.

    Panic mode sets in (engine is only 3 years old) I was able to drain all the water oil sludge mix(as much as dipstick oil changer could do). I drained and fogged all the cylinders, 1-4 wet 5-8 dry. Got the engine running again and am on oil change #5. I also changed filters.

    Oil turns to milk the minute I pour new into the engine. Engine runs 100% smooth and has normal power but seems like the oil level is going up again? Strange thing is when I drained it last time even though the dipstick looked overfilled it drained just under 7 quarts. Exactly what should be in there?? Dipstick looked like I was overfilled by several quarts??

    So what am I missing? If it was a manifold would it not take time to seep through the rings to get to the oil? Is the oil/water frothing to look more full than actual?

    Head gasket would show overheating, blowby or something rough idle right??

    Is the water just persistent? I cannot get to the bottom 100% but am very close with dipstick drainer... Any better suggestions?

    Thanks for any help or advice. I have not checked compression just yet but is next on my list i believe...

  2. #2
    Join Date
    Dec 2006
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    Chaumont Bay, N.y., USA
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    Default Re: Water in oil mystery?

    Ayuh,.... Which Merc motors ya got,..?? What vintage,..??

    Where's the boat moored,..?? How cold has it gotten,..??

    Change the oil, 'n run the motor, not at the dock, but across the pond,.....
    It needs to build motor heat to steam off the water yer not drainin' out,....
    If the oil level rises, when runnin', I'd think a cracked block, head, or a slim chance of a blown head gasket,.....
    Any Grease is Better,... Than No grease at All....

  3. #3

    Default Re: Water in oil mystery?

    running 260 4bbl engines 5.7ltr. Low is about 70 degrees here in chilly FL....hahah

    Going to try to change a few more times... It seems like maybe it aerates with water? Can that happen? I ran her and she ran perfect. Pulled all plugs after a few days running and all are dry and look perfect. Just strange that the oil keeps turning? I do see a small rust spot on the meeting of the riser and manifold? Could that actually leak into the engin oil and not cause a hydrolock?

  4. #4
    Join Date
    Sep 2010
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    Jersey Shore
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    4,635

    Default Re: Water in oil mystery?

    260? Sounds like a late 80's build.

    Pull the thermostat housing and inspect the intake water tube. Look for a hole just below the thermostat housing.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  5. #5

    Default Re: Water in oil mystery?

    Chris, what am I looking for? The engine has a new (3 year) old long block but older intake manifold... You thinking the intake manifold is shot?

  6. #6
    Join Date
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    Default Re: Water in oil mystery?

    Quote Originally Posted by carvermanz View Post
    Chris, what am I looking for? The engine has a new (3 year) old long block but older intake manifold... You thinking the intake manifold is shot?
    Ayuh,... The intake tends to rust through, directly under the t-stat,...

    Yer lookin' for a hole under the t-stat in the intake housin',...
    Any Grease is Better,... Than No grease at All....

  7. #7

    Default Re: Water in oil mystery?

    Brilliant! Never thought of that and the intake is pretty old... So just to play devil's advocate... If that were happening and I was cruising back the engine would run fine even if the oil pan was filling to the dipstick top with water? Then after it sat water would seep into the cylinders the way I found it? Possible?? Water was even with the top of the dipstick when i discovered the issue. Pulled 3+ gallons of water and oil mix...

    Side note: Water that drained out of the cylinders was clear 1-4 wet 5-8 dry
    Last edited by carvermanz; 12-02-2015 at 02:02 PM.

  8. #8
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    Default Re: Water in oil mystery?

    Well, the way to know for Sure is the block off the water passages necessary, 'n pressure test the drained long block with 'bout 15 psi of air, 'n follow the hissin' noise of the excapin' air,....
    Any Grease is Better,... Than No grease at All....

  9. #9

    Default Re: Water in oil mystery?

    I opened the thermostat housing and do not see a hole in the intake. I was going to run a scope in a bit more to inspect. Also pulled one riser to inspect that had rust on outside at joint... Must be a really small leak causing all of this... Drained the oil water mix again after about 2-3 hours run time and had 8.25 quarts removed. I ran about 2800 on the last run before realizing water was still coming in.... I hold 7 qts so it is not a massive leak, but a leak no less.

    I read a lot about GLM riser failure and have a new set in storage. Thought maybe swap first and test again... Next would be to pull the intake manifold and replace? I don't have any tools or methods to air test the cooling?? Ideas appreciated! ??

    Thanks for all the help!

  10. #10
    Join Date
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    Default Re: Water in oil mystery?

    I don't have any tools
    Ayuh,..... That's kinda a cripplin' blow, if ya wanta play a Mechanic,.....

    A qt, 'n 1/4 in a couple hours is a 'ell of a leak,....
    fatal,...

    If yer gainin' oil/ water while underway, it ain't the exhaust, as the water would be expelled over-board as usual,....

    That means, ya gotta figure out a way to isolate the Long Block, 'n pressure test it,....

    Lotsa ways to skin a cat,... a bicycle pump, 'n an ole propane tank can become a block pressure tester,...
    'n if ya got no tools, how ya gonna change the intake manifold,..??

    When ya looked into the t-stat hole in the intake, is there a rusty crusty area, directly under the t-stat,..??

    Yer more apt to find water leaks by seein' 'em from the other side,...
    Rust tracks in areas that should be dry, or oil, or exhaust, or wherever,...
    Any Grease is Better,... Than No grease at All....

  11. #11
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    Sep 2010
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    Default Re: Water in oil mystery?

    Smack the water tube under the t-stat with a flat head screwdriver and watch it go through. If this manifold is that old......
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  12. #12

    Default Re: Water in oil mystery?

    So I replaced both risers and no go... I am ordering the new intake manifold next! Question.?? After I changed the risers I found water in #1 and #3 again and the engine spun fine but would not start...Why would the engine spin with water in the cylinder? Seem like it should hydrolock??? Would this definitely mean a blown head gasket too?

    Can I use a regular cast iron intake from auto store?
    Last edited by carvermanz; 12-06-2015 at 11:25 AM.

  13. #13
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    Default Re: Water in oil mystery?

    I would do a compression test on the engine before you do anything else. If it fails compression, do a leak down to see what failed.

    If compression passes. Get the tools you need to pressure test the cooling system and the exhaust manifolds.

    Throwing parts at it is a waste of time and money.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  14. #14

    Default Re: Water in oil mystery?

    Okay so here are the test results:
    #1 110
    #2 110
    #3 110
    #4 100
    #5 220
    #6 110
    #7 110
    #8 100

  15. #15
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    Default Re: Water in oil mystery?

    Quote Originally Posted by carvermanz View Post
    Okay so here are the test results:
    #1 110
    #2 110
    #3 110
    #4 100
    #5 220
    #6 110
    #7 110
    #8 100
    Don't waste your money on this engine. It is wiped out.

    These are bad numbers.

    #5 must be a misread.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  16. #16

    Default Re: Water in oil mystery?

    I ran #5 twice... I thought it was crazy high...

  17. #17

    Default Re: Water in oil mystery?

    This engine only has about 250 hours on a new rebuilt longblock less then 3 years old??? How would it crap out so fast??

  18. #18

    Default Re: Water in oil mystery?

    Would the fact it was cold have any difference?

  19. #19
    Join Date
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    Default Re: Water in oil mystery?

    Ayuh,.... #5 has water in it, water don't compress,....

    Pressurize the cylinders at Tdc, 'n listen to see where the air is escaping,....
    Carb,..?? intake valves,...
    Exhaust,..?? exhaust valves,....
    Oil fill,..?? Bad rings/ rusted cylinders,....

    I agree, at 110 psi, shes beat,.....
    Any Grease is Better,... Than No grease at All....

  20. #20

    Default Re: Water in oil mystery?

    Merry Christmas to me! Looks like another new engine. Going brand new this time. 3.5 years is not long enough for a rebuild.

    Thanks for the help everyone!

  21. #21
    Join Date
    Dec 2006
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    Default Re: Water in oil mystery?

    So yer not gonna tell Us how the water was gettin' into the oil,..??
    Any Grease is Better,... Than No grease at All....

  22. #22

    Default Re: Water in oil mystery?

    I am just going to buy a turnkey and replace the whole engine... Guess it won't matter then?? Why tear it down just to find out...

  23. #23
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    Default Re: Water in oil mystery?

    Quote Originally Posted by carvermanz View Post
    I am just going to buy a turnkey and replace the whole engine... Guess it won't matter then?? Why tear it down just to find out...
    Education for you.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  24. #24

    Default Re: Water in oil mystery?

    Agreed! if I only had a garage or place to do that, I would tear down, buy another block and build another engine as a backup with all the components and save me the 10 grand. I just don't have the space to do it. I was diligent on my maintenance and don't think it was anything I did. Maybe the head gaskets were crappy that the company I bought the long block from? Or the block was crap, not sure? I paid $1800 for the long block. My port engine we put in in April and looks like I will now have two matching engines is a plus...

  25. #25

    Default Re: Water in oil mystery?

    Before throwing in the towel I am going to do one more thing... The compression tester was from Harbor Freight - Pittsburgh tools... Saw a few post about them being way off. I feel like it is still an intake manifold leak due to everything seeming to run okay... Gonna get a comp tester from autozone and verify before trashing, just makes no sense how the comp would be that low and it runs strong as hell. Then gonna pull the intake and do a look underneath... fingers crossed before pulling the engine next week!

  26. #26

    Default Re: Water in oil mystery?

    So not to sound too stupid.. I did not take out all the spark plugs during the test and the engine was cold.. My ignorance! Also noticed the hanger holding the inline muffler snapped and the entire muffler is now below the water line and full of water... Could this be my source of water? Would it come in at idle? Grasping at straws before the big expense...!!!

    Thanks

  27. #27
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    Default Re: Water in oil mystery?

    the tester from AZ is likely to be of the same quality as your HF item.....better off just swapping the pressure gauge itself....

    If you don't do the test correctly, the results may not reflect reality...cold doesn't hurt but leaving plugs in while likely induce low readings, especially if #5 was 'in'.

    The broken hanger isn't likely to be the issue while running but could cause issues backing or at the dock.

    if the water has been contaminating the oil for a year or two, that's enough to wearout a fresh overhaul....

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