Water in Engine Oil Help

"One thing after another,
I

"One thing after another,
I have a 94 5.0 LX Mercruiser, just purchased and went thru and changed oil and did a tune up, The timing was off and motor was cranking hard, I adjusted the timing to be correct and the motor cranks good and motor starts right up, When I was doing this it seem the motor was running Hot by the gage temp ? I had a garden hose hokked up for cooling the motor and seemed fine? Today I went and checked the motor oil to see how the level was and Now it looks like there is water in the Oil? Now What? When I changed the oil it was good with no water, How do you determine if a head gasket went out or if the block may of cracked or could it be something else?"

John'
If it's not one

John'
If it's not one thing it's another EH?
Best to do a compression test for the head gasket and even this may not show a problem.
Then a leak down / pressure test of the cooling system. This is a little harder because you need to close off all ports into the engines cooling / water jacket so it will hold test pressure.
I hope that you didn't connect the hose after the engine was hot.

"Charli, when I changed the pl

"Charli, when I changed the plugs and Oil I did a compresion check and it looked good,I took the boat out and ran for a few hours and brought it Home,I knew the timing was off because The motor was cranking hard then easy so One week later or so I checked the timing and it was advanced so adjusted it and then it started and cranked with no problem. Today i was going to go out and decided to check the Oil and noticed there was water, I did not run the motor without the water running to it I wonder if the impeller went bad ? A leak down test is it something I can do? Or best to take it somewere?"

"John,
The leak down test on

"John,
The leak down test on the cooling system is not hard but takes a fair amount of time. You would need to remove the thermostat housing and seal off the opening in the intake. Any hose from the water pump that goes anywhere but back to the water jacket would need to be removed and sealed as well.
Once you have all the ports sealed you need to put a pressure gauge into the block drain in the middle of the block just above the oil pan.
I think it's a 3/8" plug that needs a 1/2" wrench to remove.

In the drain plug on the other side of the block install a ballcock valve that you can put an air hose on.
Once everything is tight add no more than 15psi of pressure into the water jacket and close the ballcock.
Take note of the reading on the gauge after the valve is closed.
If this pressure drops off in less than an hour you have a leak somewhere.
If it will not hold pressure at all then you have a big leak and should be able to hear where the air is leaking from.
At this point add enough pressure that it may help you find the place that is broken.
The damage is done so more pressure is not going to hurt anything because the pressure can not build up. But no more than 40psi.
If it is a slow leak spray a soap and water mix around the engine to see if it is one of the hose ports or intake gasket even the water pump that is leaking.
If it is not one of these things I'm sorry to say the engine needs to have the intake removed to inspect the water jacket under it. Since you need to remove the intake to remove the head it's no big deal and if the block is not cracked under the intake then I'd look real hard at the head that was not replaced.

About all this test is going to tell you is if there is a large or small crack somewhere.
It will be hard to tell where the crack is if it is in the block and not the head until you remove the intake.

It's not often a block will crack unless it is run hot or has been frozen.
There is something very strange about this if the engine was not run hot.
The only time I've seen this is when what we think happend was the drive picked up a plastic bag and could not get any water. The owner didn't notice the engine was hot and all of a sudden it quit running right.
When he checked the gauges everything was normal.

He shut the engine down and lifted the cover and there was crap everywhere. The engine was full of water and what oil was left.

When we pulled the boat we found parts of this plastic bag on the lower unit.

We think what happened was the engine was hot from lack of water and then the bag was cleared from the water intake and the cold water hit that hot block and that was all she wrote.
By the time the engine was damaged and the owner checked the gauges the engine had cooled back down.
This is the only time of heard of a block cracking when everything running normal."

"Thanks for all the info Charl

"Thanks for all the info Charli,
I understand what you are talking about and will do this test , I do know where the drain port is and i did open today and water did come out, Do you have a idea on how to seal of the intake were the thermostat is? Also I did notice what looked like a little water leak (rusty color line)above the drain valve at were the head and block seal off ? When I was setting the timing everything sounded OK and I just noticed that the temp gage was around 240 F. Is that enough to make a block crack ? Also I do not belive the heads were ever changed or removed on this that I can tell. I will let you know when I find out more, Thanks again"

"Hey John,
Yes 240 is enough

"Hey John,
Yes 240 is enough to break the block if it was weak to start with and cold water hit it. Sounds like you had better start looking for another engine.
What you saw was the start of a crack in the water jacket.
Now depending on how bad and where it is broken it could be repaired.
It would only hold the rest of the season at best and I do not think this is a good idea. More money wasted really.
To seal the thermostat opening just find / make a plate drill two holes in it use some sealer and bolt it on where the thermostat housing would go.
You sound like you can handle some wrenching.
I have no idea of the size or how tall the boat is when it's on the trailer of course but if you have access to a concrete slab to work on it is not hard to pull the engine. If you're interested in doing this yourself I'd help walk you through it.

I feel at this point any testing is just wasting time. The block sounds like it is junk. No offence.
Depending on how big the boat is you can have the engine on the ground in as little as 2 hours.

If you feel you can and want to do this let me know because there is a tool you are going to need to order so you can get the job done correct."