www.iFourWinns.com

Set out last weekend for a 7 mile trip on the Chesapeake Bay. About halfway through the trip experienced a loss of power from the engine. Was able to limp back to the dock at low speed. Hauled the boat out of the water and now have it on the trailer in the driveway. The engine oil changed to a beige “milkshake” like consistency and discharged from the top of the engine and into the bilge.

From looking at other posts this appears to be a cracked head or failed gasket. I plan to take it to a mechanic in the next few days and have it diagnosed, but in the mean time I was wondering what could have caused this. I’ve had the boat for 13 years and always winterized it the same way with no issues. Also, its September and I’ve been using the boat all summer since putting it in. I feel like a winterization issue would have showed its self back in the Spring. There was no evidence of overheating. I replaced the impeller and thermostat at the beginning of the season.
A mechanic replaced the exhaust manifolds two seasons ago when water was getting into the cylinders.

Is taking apart the head gasket a big job? Does it require any special tools? I may give it a shot. I have done allot of external work on the engine (water pumps, thermostat housing, starter, etc.), but never attempted any internal work. I figure at the very least I can get it cleaned up for the mechanic.

1999 Volvo Penta 4.3GL PWTR
Four Winns 190 Horizon

What manifolds did they use when they replaced them? If it was GLM, they were known to have sealing problems....I'd drain them, remove them and look for evidence of water getting in that way first. Look for rust trails in the center exhaust passage of the manifold and in the exhaust ports of the cyl head.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Potentially a manifold to riser gasket, as Lou has mentioned...
Oh & flush your engine oil and change your filter at your absolute earliest convenience!!!

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2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

It sounds like you got a LOT of water in the engine, so I don't suspect that it's from the exhaust manifolds.

The exhaust manifold problem is likely to show as a hydrolock, which is water in a cylinder after shutdown, which prevents the starter from being able to turn the engine.

You stated you had a loss of power while the engine was running, and oil/milkshake came out the top of the engine. That much water must have come from a cracked block or bad head gasket. As you said, it was fine all summer, so let's hope that it is the head gasket. What is your winterizing procedure...your not sucking up antifreeze from a bucket/tank are you?

It would not be hard for you to take off the manifolds (intake and exhaust), valve covers, then remove the heads before turning it over to your mechanic. You could clean up all the gasket surfaces, but take pictures of them first. If you want to take it farther than that, then you definitely would want to get a shop manual.

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

As a first step try a compression test; this could verify a bad head gasket or rule it out. Another common cause of water in the engine is a rusted out intake manifold . If neither of these are causes; you could have a cracked block or head.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II