Water in the oil???

[Wish]

Not my boat but one I know of. What would be the cause(s) and what would it cost to fix (parts/labor) each possibility. No details known other then water in oil and it runs (not sure how...)

 

99SN GT-40

[thager]

Check the manifold gaskets at the elbows. I had a 72 Hydrodyne IO that did that. Boat ran fine but was getting milky oil. Thought for sure it was a head gasket but ended up just being the manifold elbow gasket on the right side. Whew! Cost me $25.00 in 1982. Good luck!!

[Wish]

So possible head gasket -cost?

possible manifold elbow -$25

[ToddF]

 

Head Gasket

The head itself

Cracked block(rare)

 

most likely it isn't good.

 

[Wish]

@ToddF any idea on the cost of those to have done?

[ToddF]

head gasket 500 dollars or more, if you have to shave the head because if overheated and got warped. The head gasket is 50 dollars, but there is a lot of labor to get to it.

 

Cracked block a lot more!

 

I would pull the plugs and look at each one. You might be able to tell more from that. Like if one has oil on it.

 

Hopefully that isn't the case

[BraceMaker]

Before you get too crazy...

 

How often has this boat been run lately? In some cases, moist environs, and lack of running time leads to moisture condensation in the blocks, you'll see this in boats stored on the water but not run frequently. Good solution is to change the oil and see if the problem goes away.

 

 

[Waternut]

I agree with @bracemaker unless you found this issue while changing the oil during winterization of the boat. If that's the case, now is the time to look into the problem so that you aren't battling a potential problem at the beginning of next season.

 

If you're mechanically inclined and can get your hands on a torque wrench, you can change the head gaskets yourself. Gasket kits are like $40-$50. It's not a difficult task at all but the heads and exhaust manifolds are pretty heavy. If the heads are warped, you would have to get them shaved flat at a machine shop but even then, I'd rather do that in nov-dec timeframe than april-may of next year when you have that desparate itch to ski again.

 

@ToddF makes a good point with the spark plugs too. You can also shine a light into the spark plug holes and if one piston looks really clean and the rest look black, then that is likely the one with the problem because the water steam cleans the piston.

[boarditup]

Diagnosis:

 

Pull plugs one by one. Inspect for evidence of excessive oil (black, slick) or water (white deposits)

 

Perform compression test - all should be within 5-lbs of each other

 

Harbor Freight has an inexpensive bore scope to inspect the cylinders. It is a good way to see the top of the piston and verify any scorching patterns on a suspect cylinder.

 

If both previous tests are negative, then likely manifold gaskets need replacement. Exhaust manifolds are a wear item. They may also require replacement. You are about due. So if so, replace the entire assembly.

 

If one or the other is positive, you likely either have a head gasket, valve, or cracked head - in that order.

[Jody_Seal]

You got all that Brian? :)

 

If it was me I would take a good look at the Lower intake gasket before I started into the heads. check and see if any fasteners are loose.

 

Re-condition heads (cylinder head service PC) $200

gasket set $75.00

About 4 hours R&I @ $85.00 $340.00

 

Don't really like going through just the top end of a ski boat motor with out going through the bottom end also. Seems other problems pop up after top end job! If it is coming partially apart might as well go through the whole engine. can usually refresh the engine for around $2500-$3000 engine out and back in the boat. That is provided no pistons or crank issues arise.

Keep in mind the GT-40 was prone to piston slap issues and a few other minor engine component Failures.

[DW]

The causes of water in the oil are numerous, so a good place to start is to review what might have happened recently. Has the boat overheated, torn an exhaust flapper, lost an impeller, sat open in a big storm, dropped in the lake with the plug removed, etc... Those are clues as to what might be the problem which would help immensly in the sleuth work to pinpoint what is the true cause.

[Morg]

All good advice above.

 

Check your water system to make sure it is not plugged on exit.

 

Lots of ways for water to get into the oil. Condensation the most common. Leaking somewhere into the exhaust & being sucked in during reversion also common. You can plug off the water inlet & put a pressure gauge & put air pressure to the system. NO MORE THEN 5 lbs of pressure. Listen for leaks, pull plugs, open up carb butterfly. If this does not show where the leak is. Do a leak test. release the valves so they are all seated, pull the plugs & see if you are leaking cylinder to cylinder.

 

Remember changing oil will not get rid of all of the water. Run the boat & check, easy way is to pull a valve cover. Then run it & try to get warm. Look @ the pvc valve, getting the motor hot enough to get steam is the goal. Then check again to see if you have more or less milk. All the while paying close attention to make sure the motor is running okay & you are not causing more damage.

 

Head gasket or cracked block as said above should show on the plugs. Also as said above, unless the boat had a problem I doubt head gasket or cracked. Look @ exhaust & manifold crossovers.