1992 Mercruiser 4.3 Alpha One Gen II has water in oil after rebuild.

[nic420]

The boat is 1992 Bayliner Classic 2252 that has 1992 Mercruiser 4.3 with 1 piece rear main seal. I got water in oil after rebuild. Changed oil 4 times and still has water.

Motor was frozen when I got the boat. Tore down the motor and there was water in cylinder #4 & #6. Had a machine shop rebuild the heads and hone the block. It was a complete rebuild and ran perfect accept for water in the oil. I have not torn down the motor again yet per I've read somewhere in the forum there are tests you can do to find out where the leak or cross over is at. I bought a leak down and a compression tester but don't know what to look for during the tests. Please advise on how to troubleshoot.

Do you think if I replace all of the following gaskets it would solve the problem?

• Head gaskets
• Intake gasket
• Exhaust manifolds & elbows gaskets

Also, please advise where I can order a marine head gasket set. I'd ordered a set without the (12) 18-0518 Valve Stem Seal and (6) 18-4024 Intake Valve Stem Seal
at the time of the rebuild and not sure if I should have ordered the ones that comes with the stem seals. I didn't use the valve stem seals or the intake valve stem seals when putting the motor back together because I did not see those seals during the tear down. Could that be the problem why I got water in the oil? Please help. Thank you.

 

[nola mike]

Valve stem seals shouldn't do it. Didn't you replace all of the gaskets already? How about intake/exhaust manifold and risers? A compression test would tell you if something went really wrong with your rebuild, but best bang for the buck would probably be to pressure test the coolant system.

 

[nic420]

Valve stem seals shouldn't do it. Didn't you replace all of the gaskets already? How about intake/exhaust manifold and risers? A compression test would tell you if something went really wrong with your rebuild, but best bang for the buck would probably be to pressure test the coolant system.

Thank you for your reply. I had replaced all the gaskets and got mew exhaust manifolds and elbows too.. However, during the install for the intake manifold gaskets, I had them backward. I had them where the water that comes from the thermostat housing enters heads were blocked by the blanked part of the gaskets. I reinstalled the same ones back with the blanked part of the gaskets at the rear of the motor by the distributor. Could the intake gaskets be damaged from the wrong install? The blanked part of the intake gaskets now has bulges on them and are not flat how the were when new.

For the pressure test, does the motor have to be at TDC? I did a pressure test and heard bubbling noises from the carb. When I tried to turn the motor to TDC for cylinder # 6 to test again i would hear air coming out from the exhaust manifolds inlets. I'm not sure if I'm doing the pressure test correctly.

 

[nola mike]

Can't picture what you're talking about with the intake, but if your intake manifold is leaking, then yes, that could be a source of water. Doesn't sound like you're doing much with your pressure testing. Are you just filling the cylinder with compressed air? If you're not at TDC on the compression stroke then the air will just go out an open valve. Either way, you're pressurizing the combustion chamber. If you can hear air in your cooling system then that might be of some value, but kind of tough with open cooling I'd think. Anyway, I was talking about pressurizing your cooling system. There are a bunch of threads around telling you which hoses you'll need to block off and how to pressurize it.

 

[alldodge]

However, during the install for the intake manifold gaskets, I had them backward.

Reusing a gasket is never a good idea for head or intake. It was installed backwards and compressed, then removed and re-installed. Use a new gasket.

 

[Rick Stephens]

Sorry to say that a cracked block or head is the most likely culprit. There are many places a crack can be that cannot be seen with magnafluxing.

Years back I went through the same kind of thing, had a lot of water in a motor that I purchased in a partially refurbed hull. It was a brand new rebuilt that sat in a boat as the boat was being rebuilt around it. All the indicators looked like they let water enter through the open carburetor and not a crack somewhere. So I went ahead, had it magnafluxed and rebored. Until I ran it I was half expecting that a crack would still be present and water get in oil, which would necessitate replacing the block and or heads. Only way to tell for sure is to build and run it, unfortunately.

 

[tank1949]

Thank you for your reply. I had replaced all the gaskets and got mew exhaust manifolds and elbows too.. However, during the install for the intake manifold gaskets, I had them backward. I had them where the water that comes from the thermostat housing enters heads were blocked by the blanked part of the gaskets. I reinstalled the same ones back with the blanked part of the gaskets at the rear of the motor by the distributor. Could the intake gaskets be damaged from the wrong install? The blanked part of the intake gaskets now has bulges on them and are not flat how the were when new.

For the pressure test, does the motor have to be at TDC? I did a pressure test and heard bubbling noises from the carb. When I tried to turn the motor to TDC for cylinder # 6 to test again i would hear air coming out from the exhaust manifolds inlets. I'm not sure if I'm doing the pressure test correctly.

Is there a chance water is dripping into motor via carb? My opinion, never re-install gaskets after torqueing them. Just my 2 cents. Take out all plugs and retest pressure after squirting inside pistons with oil. Make sure compression tester's release valve doesn't leak. My did one time. Take measurement and compare. Find piston whose pressure is radically off. If off, pull head on that side and pray block is not cracked. Hearing air coming out is not good.

 

[nola mike]

Hearing air coming out is not good.

Hearing air coming out is just fine as long as the cylinder isn't at tdc on the compression stroke...

 

[tank1949]

Hearing air coming out is just fine as long as the cylinder isn't at tdc on the compression stroke...

Author wasn't clear and I agree.

 

[QBhoy]

Hi. So it’s likely one of two things here.
your original post says you replaced the exhaust and riser gaskets. That won’t stop water ingress to the engine, if there has been frost damage to the actual manifold/riser.
As you’ll know, cylinder 4 and 6 are right next to each other too. So it’s entirely possible that there is a conjoined loss of seal between the two, at the cylinder head too.

 

[Lou C]

When you said “frozen” do you mean locked up or freeze damaged?

 

[nic420]

When you said “frozen” do you mean locked up or freeze damaged?

Locked up.

 

[nic420]

Author wasn't clear and I agree.

My apology. I did the following for the pressure test:

• Drained water from exhaust manifolds
• Could not drain the block because the drain plug was hard to get to
• Drained oil from pan
• Plugged the hoses that connects to the exhaust manifolds and risers
• Blew air in to the water intake hose at the back of the transom
• Motor was not at TDC
• Heard air coming out of both risers hose inlets
• Check oil pan drain and it was filled w/ water

Could blowing air during the pressure test caused left over water from the block to go in to the oil pan?

 

[nic420]

Hearing air coming out is just fine as long as the cylinder isn't at tdc on the compression stroke...

Motor was not at TDC.

 

[nic420]

Hi. So it’s likely one of two things here.
your original post says you replaced the exhaust and riser gaskets. That won’t stop water ingress to the engine, if there has been frost damage to the actual manifold/riser.
As you’ll know, cylinder 4 and 6 are right next to each other too. So it’s entirely possible that there is a conjoined loss of seal between the two, at the cylinder head too

Hi. So it’s likely one of two things here.
your original post says you replaced the exhaust and riser gaskets. That won’t stop water ingress to the engine, if there has been frost damage to the actual manifold/riser.
As you’ll know, cylinder 4 and 6 are right next to each other too. So it’s entirely possible that there is a conjoined loss of seal between the two, at the cylinder head too.

Bought new exhaust manifolds and risers at the time of rebuild.

 

[QBhoy]

Bought new exhaust manifolds and risers at the time of rebuild.

Head gasket suspect perhaps or a frost crack between the two cylinders ?
Edit...just saw you meant frozen as in locked. Not actually frozen.

 

[QBhoy]

Just a thought. May not be the case...but did you rebuild the same marine engine or is this a engine from a car ? If it’s not a marine engine...something in my head says that the cam may allow an overlap of valves and their operation. Small chance of there being a moment of taking in water from the exhaust. Just a thought.

 

[Lou C]

What I would have done first:
Replace the hoses that feed water from the stat housing to the exhaust manifolds with clear hose. Put the boat in the water and run it long enough to get the engine hot enough to keep the stat open. Get someone to run it above idle while you check if there are bubbles in the cooling water. If so this indicates exhaust/combustion gas in the cooling water. That comes from leaky head gaskets or cracked head or block.

 

[nic420]

Just a thought. May not be the case...but did you rebuild the same marine engine or is this a engine from a car ? If it’s not a marine engine...something in my head says that the cam may allow an overlap of valves and their operation. Small chance of there being a moment of taking in water from the exhaust. Just a thought.

Same marine.

 

[Rick Stephens]

To pressure test a block cooling system:

1) Remove hoses to manifolds and plug them.

2) Remove the 'IN' water hose, that comes from the transom, at the thermostat.

3) Either plug the open thermostat port or use it to make up a connection to a schrader valve.

4) Apply max 15 pounds pressure to cooling system. Should hold air indefinitely. You can use a mechanics stethoscope to listen for the leaking air as well.