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  1. #1

    Default Got water in engine heads? How and Why? please help!

    Last weekend my engine (1993 4.3 LX mercruiser) hesitated a few times (loss of power) than finaly stalled. I tried to restart it but it wouldn't turn over like the starter was gone (i know its not the cause for the stalling). Brought the starter in and had it rebiult so i can at least test for the reason it cut out in the first place. Anyway, put it back in today and same thing, won't turn over. i was told by my car mechanic friend to take out 1 or all 6 spark plugs to then see if it would turn over. Sure enough i take out the first plug and tons of water came out, i then took out the other 2 on that same side and they were also wet. then took the first plug out of the other side and the exact same thing (tons of water from the first plug then the other 2 were wet).
    I then turned it over quite a few times to get most of the water out. it seemed like it just kept coming out. I ended up cracking one of the plugs so went and got all new ones. put them in, then tried starting the engine (after getting the water out and letting it dry for a while). it fired up, ran rough for 20-30 sec then ran fine. turned it off and on many time and ran great. Seem to run even better than before with the new plugs. I gave it some throttle as well and it runs fine (i didn't drive it anywhere of course). Took out the plugs again to see if there was any water and they were dry. So my questions are, How did the water get in there????? I would like to ad that there is no water in the engine oil.
    I'm guessing its not the gaskets because it happenned to both sides and there is no more water getting in the heads.
    I'm guessing the block is not craked as i first assumed because it happenned to both sides and again no more water and no water in the oil.
    Can water come up the exhaust and into the manifolds? The boat did come to a quick stop and lots of water did come rushing up when the boat stalled?
    Is there some sort of "check valve" that stops water from coming in?
    Please help!!!!! When I saw that water coming out my heart dropped. Sorry about the long post but just trying to explain in detail. thanks

  2. #2
    Join Date
    Feb 2009
    Location
    Lindisfarne, Tasmania, Australia
    Posts
    452

    Default Re: Got water in engine heads? How and Why? please help!

    It is possible to get water back up the Exhaust, and into the engine, but you won't get water into the cylinders that have both Valves closed.

    I don't suposed you tasted the water to see if it was Fresh, or Salt (ie. the boat in fresh water or salt water). Coolant water will be coloured.

    If there is any amount of water in the combustion chambers you won't be able to turn the engine, with the spark plugs in place because of Hydro-locking, where the piston cannot compress such a volume of liquid.

    I am unaware of any check-valves in the system, as in 99% of the time, when the engine is running, the Exhaust pressure doesn't let the water in.

    If the water came in upo the Exhausts, then you did the right thing by drying it out, and firing it up again. The heat will soon get rid of any residue.

    Bruce.

  3. #3

    Default Re: Got water in engine heads? How and Why? please help!

    Hi, its a fresh water boat. It was definately hydro locked. i thought the starter was gone because it wasn't turning over. I guess i should have took out the plug but would have never though water would be in there. So, no clue on how water could have got in there? thanks

  4. #4
    Join Date
    Feb 2009
    Location
    Lindisfarne, Tasmania, Australia
    Posts
    452

    Default Re: Got water in engine heads? How and Why? please help!

    If as you say, you stopped suddenly, and the motor was stopped, and the water came flooding over the transom, then there would be sufficient hydraulic pressure to force the water back into the engine, through the exhaust pipes and manifolds.

    I take it that your engine is an Inboard Shaft Drive, with straight-through watercooled manifolds and hoses to the Transom?

    In order to stop water from coming back in, some people install "flapper" valves on the exhaust end where it exits the Transom, to stop the back-wash from happening, as in a lot of cases, the engine sits low in the boat, in relation to the waterline, and it doesn't take much back-wash to get a gut-full.

    Bruce.

  5. #5

    Default Re: Got water in engine heads? How and Why? please help!

    I'm really thinking thats what happenned. Normaly, even when you stop quick the engine is still running so the exhaust pressure also helps prevent this from happenning. In this case the engine had lost power and stalled (which is a whole other problem) so the boat stopped very quickly from a 30-35 mph speed and the water came rushing up.

    So, boats don't come with "flapper valves" installed in the manifolds?

    Sorry, i'm not 100% sure on what type of engine it is? Sounds like what you said "Inboard Shaft Drive, with straight-through watercooled manifolds and hoses to the Transom". Water and exhasut does comes out through the transom so i'm guessing thats what its called.

    So you say it doesn't take much to get a back wash and water come up through the manifolds?

  6. #6
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default Re: Got water in engine heads? How and Why? please help!

    maybe, thats what happened

  7. #7
    Join Date
    Feb 2009
    Location
    Lindisfarne, Tasmania, Australia
    Posts
    452

    Default Re: Got water in engine heads? How and Why? please help!

    If the engine is stopped, and the water rushes in, if the Exhaust and Intake Valves are open, even partially, there is only the throttle plates to create an "Airflow Stop" to keep the water from progressing into the engine.

    And, seeing as you were cruising at speed, and the engine stopped dead, I assume that the Throttle was still wide open at the time, then you would get that "Flow-through event.

    Bruce.

  8. #8

    Default Re: Got water in engine heads? How and Why? please help!

    Did you find a solution to this problem?
    I have the exact scenario and engine as you. Engine running 2200 RPM chugged and died... Cleaned out all water, replaced plugs, two days of running later same thing and always while running.. Leads me to think it cant be exhaust risers. How can water come up and enter ALL cylinders when exhaust is coming out at a high rate?
    I am thinking cracked INTAKE manifold. Perhaps that is also your trouble as well?? Gonna pull off manifold tonight. Will keep y'all posted.
    Good Luck
    Joe

  9. #9

    Default Re: Got water in engine heads? How and Why? please help!

    Hi, ya it sounds like my problem was a little different. Mine only happenned once when the engine died while cruising at 3600rpm (electrical fuse). When the boat camw to a sudden stop i still had the throttle open and the rush of water came up the risers. The exhaust flappers that were supposed to be in there where gone (one was half there and the other one was completly gone). I was told in some boats (depending on how the boat sits in the water they are no longer needed) but in my case they are. Espacially if the boat comes to a quick stop with no exhaust pressure helping to stop the water from coming up. In my case, i had worst case scenerio. Engine died, boat stopped from a 35mph+ speed, NO exhaust flappers = water in the heads! If your is happening while the engine is still ON with exhaust pressure i would have to think its something else. How old is your boat? I would check to see if the flappers are still there anyway. Real easy to check. just undo the clamps at the rubber elbow on the exhaust and there right there. Less than 10min to replace both. Good luck. Later

  10. #10

    Default Re: Got water in engine heads? How and Why? please help!

    I will check them out. Pulled off the intake manifold but saw nothing obvious. Riser flaps tommorrow. Thank You

  11. #11

    Default Re: Got water in engine heads? How and Why? please help!

    Please update with what you find... I have had the exact same thing happen to me today and needed a tow... hesitation, eventual stall, and water in both sides. I didnt really have that much of a "back wash" when I stopped so I doubt that the riser flaps are the problem, and I suspect that the hesitation issue is somehow related, in other words I think the water is getting in while its running and causing the hesitation and eventual stall.

  12. #12

    Default Re: Got water in engine heads? How and Why? please help!

    A little more on mine... after removing plugs and cranking away I managed to get the water out of the cylinders. Compression test showed good in all cylinders. Got the plugs back in and got it fired up in the driveway, just ran it for a few seconds without a water hookup, afraid that if I pumped the water through I'm locked again. Pulled the risers, mine are are in great shape, no need to replace. Havent burrowed down to the flaps yet. Still plugging away and looking for ideas.

  13. #13

    Default Re: Got water in engine heads? How and Why? please help!

    I have seen that happen a few times now, especially people pulling skiers with thru hull exhaust, flappers good, pull plugs, a couple 3 oil changes, and then they fog the cylinders until next time taken out and no problems afterwords, just one of those perfect storm type things? when fogging the cylinders, don't be surprised if it smokes a lot for a few minutes.

  14. #14

    Default Re: Got water in engine heads? How and Why? please help!

    I spoke yesterday with a marine mechanic about this phenomenon. He suggests that the water that enters the engine is the engine cooling water that is being discharged around the exhaust outlet. Since this water is being discharged under pressure.....he suggests there are times...under certain conditions...that water pressure can overcome the exhaust pressure and the water can force its way back up the exhaust into the engine.

    He told me that Merc has redesigned their exhaust systems and eliminated the riser in order to combat this. I'm not familiar with Mercs engine design on newer models so I don't know.

    But this ingestion of water happened to me 20 years ago with an OMC 260HP. I now just recently bought another boat with a 454 Alpha One and don't want to see this happen again.

    The peculiar thing about when it happened to me before is that I was doing nothing out of the ordinary....simply cruising along very slowly..basically at idle speed.....the engine stalled...wouldn't start....removing the plugs revealed all cylinders filled with water.

    I did an oil change....a compression check....all was good...and it never happened to me again as long as I owned that boat.

    Any ideas on how this happens and how to avoid this happening again would be greatly appreciated.

  15. #15
    Join Date
    May 2007
    Location
    Kawarthas
    Posts
    3,160

    Default Re: Got water in engine heads? How and Why? please help!

    Quote Originally Posted by Utilo View Post
    He told me that Merc has redesigned their exhaust systems and eliminated the riser in order to combat this.
    no they haven't.

    What they did was design a "dry joint" manifold that still has a riser, and still mixes cooling water exhaust with engine exhaust.

    The only design improvement is separating the passages through the riser to manifold joint by a few inches, so if water leaks from a failed seal, it will leak down the side of the engine, rather than into the exhaust.

    All the reversion issues are unchanged and the flappers are still there in the new Mercruiser packages

  16. #16

    Default Re: Got water in engine heads? How and Why? please help!

    I have an intake manifold on order as well as thermostat and thermostat housing. I ordered the manifold because it was heavily corroded inside and regardless if that was the problem I was not going to reinstall... I will get it back together and see if the problem persists. I poured water into the manifold but did not get any coming out the intake ports so I am not confiden that this is the problem unless the crak is opening up with heat??
    It seems every post regarding hydrolock is directed to risers so that just may be my next step.


    Quote Originally Posted by striker3636 View Post
    Please update with what you find... I have had the exact same thing happen to me today and needed a tow... hesitation, eventual stall, and water in both sides. I didnt really have that much of a "back wash" when I stopped so I doubt that the riser flaps are the problem, and I suspect that the hesitation issue is somehow related, in other words I think the water is getting in while its running and causing the hesitation and eventual stall.

  17. #17
    Join Date
    Sep 2006
    Location
    Coquitlam, British Columbia, Canada
    Posts
    193

    Default Re: Got water in engine heads? How and Why? please help!

    Somewhere back on this site, someone posted pictures of the old style risers and the new style that they came out with to combat this water ingestion problem. Someone more capable at finding the pictures may be able to look into this.

  18. #18
    Join Date
    Apr 2007
    Location
    Seattle, WA,
    Posts
    873

    Default Re: Got water in engine heads? How and Why? please help!

    Quote Originally Posted by striker3636 View Post
    A little more on mine... after removing plugs and cranking away I managed to get the water out of the cylinders. Compression test showed good in all cylinders. Got the plugs back in and got it fired up in the driveway, just ran it for a few seconds without a water hookup, afraid that if I pumped the water through I'm locked again. Pulled the risers, mine are are in great shape, no need to replace. Havent burrowed down to the flaps yet. Still plugging away and looking for ideas.
    Striker I am afraid you will probably have to pull your lower unit and check your impeller. Even after a few seconds of running with no water will fry the rubber blades. If you get water in your cylinders from running on the hose that will tell you where the water is coming in from. Probably exhaust manifold. If no water then good chance it's your exhaust flapper.

    I think most of your problems stem from flapper issues. The flapper is a one way flap in your exhaust downtube that prevents backwash up the pipe. Since most of you have V engines and you're getting water in both banks that would be the first guess. If it were just water in one bank I would say you have a cracked exhaust manifold.

  19. #19

    Default Re: Got water in engine heads? How and Why? please help!

    Last night I separated my risers from the exhaust manifolds (only broke one bolt) The gaskets between the riser and manifold were in poor condition and could very easily be allowing water to transfer from the riser and directly inside the exhaust manifold and into the cyl head.
    I gotta say it is nice to see a definate problem. I would hate to re-assemble everything and come back in being towed behind another boat... It is my turn to do the towing!!

  20. #20

    Default Re: Got water in engine heads? How and Why? please help!

    "Even after a few seconds of running with no water will fry the rubber blades. "

    Yup....sorry to say I learned that the hard way many years ago.

    "If you get water in your cylinders from running on the hose that will tell you where the water is coming in from."

    Could be wrong but my bet is that there will be no water getting in when running on a hose.

    "The flapper is a one way flap in your exhaust downtube that prevents backwash up the pipe"

    True...but it seems the water ingestion isn't always in a backwash scenario...as happened to me. I was simply putting along very slowly winding my way between some islands at basically idle speed...perhaps around 800 RPM or so....when my engine just quit.....both sides filled with water. This is the huge puzzler for me.

    As I mentioned...my marine mechanic friend suggests that it is often times the engine cooling water being discharged that is some how finding it's way back into the engine via the exhaust. And I'm still having a little trouble getting my mind around that theory. But it does sound more plausible to me since in my case I was not in a backwash situation.


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