I have a 1971 Century Coronado with lots of water in the oil I just bought last October. It ran great when I put it away but now after 10 hours of running it this spring had 1-2 gallons of water mixed with the oil. Compression test showed low compression in three cylinders, again, it runs fantastic.

I pulled the heads off and as you can imagine it looks like a vanilla shake exploded and is covering the rockers...the area under the carb but the cylinder walls and piston tops look perfect. There was about 1 ounce of water in the cylinder with the worst compression, 55#. I'm assuming its either a warped head or blown gasket.

I need to check the heads, replace gaskets and clean up the motor. What is the best way, other than yanking the motor, to get that oil/water sludge out of the pan and all the other places it worked into?????

 

On a boat the gasket probably rusted thru. With he top end off ? Just pull the motor. With that kind of oil mixture you need to replace the bearings !!!!! the water/oil damages them. They may look good but in 6 months when you spin a bearing. It is cheap insurance

 

I agree with TVLynn you should go through the motor and replace bearings, rings etc. inter mix is not a good thing... You said water?? what kind of water??? Salt water.. Even more of a reason to rebuild it...Bill

 

It is fresh water.

 

I agree... Pull it and Go threw it

 

Is the boat an IO or a Jet? (Edit: Just googled it, direct drive: Nice boats!) Usually water in the piston is from one of a couple sources. The head gasket is a likely suspect but reversion is a very likely possibility as well. If the compression is low was the head gasket obviously compromised? If not is is possible that a valve was stuck open and it sucked water back in from the exhaust. (I assume it has water cooled logs or water injected headers). If it has logs, have them pressure tested to make sure they are not leaking. They are known for rusting thru and causing reversion problems. Edit: It should have water cooled logs (have them pressure tested for leaks).

Also was the boat ran recently with a hose hooked up to it? Many times people turn the hose up full and push water past the head gasket into the engine. Cooling systems can't handle the full water pressure of most household garden faucets.

 

This is not quite the silliest thing I ever heard. If running the cooling system at water pressure----somewhere between 25 and a hundred psi--blows a head gasket--that head gasket was DONE and you've done yourself a favor by finding it

Any idea? What the combined heat and pressure of a firing cylinder is?

 

Any idea how many times we see just this thing in jet boats and V-drives alike? Of course I'm sure you're more up on it than I am. So since it's not my monkey nor my football, carry on.