Logo
FULL SITE MENU

1986 Grady White Hydro-locked 5.7 liter V8 with an OMC Cobra sterndrive

L

Lab-Lover

New member
I started this thread in the electrical forum because the starter wouldn't turn the engine over. Now I'm moving to this forum because the problem turned out to be hydro-locked cylinders rather than a simple problem with my starter. Ya gotta love boats, there's simply no end to the opportunities to learn things. :confused:

To recap the original problem and solution: Bono suggested that the engine was probably hydro-locked so I pulled the sparkplugs and cranked the engine. lo and behold I had water spraying out of at least 4 of the cylinders, maybe all 8. Cranked it until most of the water was gone, cleaned the plugs and put them back in, pumped the gas a couple of times and she fired right up!!!!! Ran it long enough to heat up and dry things out. The engine oil is still nice and clean so at least I know the rings have a good seal, tough way to find out though, I think I would rather run a compression test instead.

Now the question is, where did the water come from? When the problem ocurred I had just finished a 4 hour fishing trip of constant trolling and pulled into the slip nice and slow on calm water, with no following wave which might have forced water into the outdrive. The engine killed as I shifted from forward to reverse which I think is an issue with the shift interrupter that I will have worked on this winter. We poled the boat into the slip, tied off and tried to restart the engine but it wouldn't crank over so it must have immediately hydro-locked. Could the hot engine have sucked water up thru the exhaust manifold and into the cylinders? Or when I shifted into reverse and the engine died could it have forced water into the engine? Either way, is this a common occurance on these engines and outdrives and how can I stop this from happening again? Is the only way to fix it to pull the plugs and pump the water out when it happens?

Thanks in advance for any input, solutions and ideas.
 
Either way, is this a common occurance on these engines and outdrives and how can I stop this from happening again?
Click to expand...
You tell me. Keep your spark plug wrench handy and run it. However it might be something more dire, like a warped head/blown head gasket/cracked block.
Generally speaking, no. These engines/drives aren't known for it. If someone put in a car engine, then yes it can easily get hydrolocked.
 
have you checked your flappers?...theyre in the bell housing and prevent water from entering while in reverse or experiencing a following sea...im no expert , but thats what they are designed for and ive read that they can melt and cause water to enter your engine...easy to check ,just pull off your exhaust at the bell housing and stick your hand in there , its spring loaded , if you dont feel it working properly , there may be your problem ...dimitri
 
http://www.marineengine.com/boat-fo...446-water-going-into-the-engine-into-the-oil&

Click on the link to pressure test the block.

Or first perform a compression test with all the plugs out, warm engine, and throttle fully down.

To your question on how water can get into the cylinders, there are many way's:

Head went.... cooling passage rusted thru.

Mani went... cooling passage rusted thru.

Elbow " riser " went...cooling passage rusted thru to the exhaust passage.

Intake went.

Head gasket went.

When you conked out hot engine drew the water backwards into open valves.

If this were my boat first thing compression test, Good compression move on to the link and perform a pressure test of the block cooling passages.

Please post back we will go from there.
 
Great info eveyone. Especially the discussion about failing manifolds and risers. I never really understood why you would have to worry about them and replace them from time to time but constant dampness certainly would take its toll on raw cast iron. I am going to reinspect the crankcase oil to make sure it isn't contaminated with water and then take the boat on its the final run of the season..... over to the repair shop. I want to have a suspicious clicking in the sterndrive checked out and a new shift cable installed over the winter so I might as well have them run a complete diagnostic before Spring, including a compression test and check out the entire exhaust system, manifolds, risers, flappers and whatnot. I will also inquire about having a "leak down" test performed. Hopefully the repair shop will know what I'm talking about better than I do.

Thanks again for all of the help. I'll update this post as I learn more about the boat and engine.
 
Back
Top