water in 3 and 6

[MCFAM]

So my boat thermo locked and never mixed the oil and water but it did have about 1/2 quart of water in the bottom of the pan . I pulled the plugs to do a cylinder test to find where it might be bad and water came out of 3 and 6. It is a 4.3 mercruiser, do I need to do any other checks or just figure both head gaskets are blown and start tearing it down?

 

[MCFAM]

so I went ahead and did the compression test all cylinders were 121 except 6 which did spit some more water out and was only 120. so what now?

 

[I Can Fix That]

pull the valve cover off and get both #6 valves closed by turning crankshaft until both cam lobes pointing upward-ish or loosen rocker arm nuts and then do a cylinder leak test with the proper tool or blow air with air compressor hooked up to your compression tester hose into the cylinder and see if air/noise comes out of intake or exhaust manifolds or oil passages to the block. could have cracked stuff, leaking intake gasket or head gasket

 

[IdahoDoug]

How did it happen?

 

[MCFAM]

it was an a bunch of little things. heat alarm was disconnected, thermostat was wrong (180 instead of 160), and just being new to the boat. going through the school of hard knocks.

 

[NHGuy]

If it turns out that there's no block crack you could have gotten water in through the exhaust. If you had the risers off and rebolted them without changing the gasket there's a possibility that water got from the exhaust water jacket into the exhaust gas tract where the riser and manifold bolt together.
Since you say there was water in the oil pan that did not mix with the oil it had to have gotten in there after the motor was turned off. If the water had been in there with the engine running it would have turned to a brown emulsion goop.
Pressure test the cooling system by line clamping the outlet hoses and put 15 psi in the inlet. Listen all around for air escaping. Do this at a few crank angles. Listen at the carb, exhaust, and valve covers.

 

[MCFAM]

what would be the best way to put air into the line? is there a tool I could buy or make to add air with?

 

[HT32BSX115]

it was an a bunch of little things. heat alarm was disconnected, thermostat was wrong (180 instead of 160), and just being new to the boat. going through the school of hard knocks.

Wrong t-stat doesn't cause this sort of problem.

If the block/head(s) is/are not cracked and the head gaskets have not failed, water can easily get in through the exhaust.

Failed riser gaskets, cracked risers and/or exhaust manifolds will cause it. The risers and manifolds are full of water immediately after shut down. After the engine stops, the water leaking through cracks of failed riser gaskets will run right in through the exhaust valves that remain open.

Regards,


Rick

 

[MCFAM]

How do I test the riser gaskets or do I just pull them 1st and check them (is there a test for doing this) before I tear into the head gasket

 

[MCFAM]

How do I test the riser gaskets or do I just pull them 1st and check them (is there a test for doing this) before I tear into the head gasket