Water in oil.

[pdublya]

Went to perform the winterization oil change on my 15’ SAN210 with the 350 and unfortunately found water in the oil. Put last years used oil in after draining and rain with the hose and the used oil came out just as milky as the previous oil change. Any DIY inspections I can do before I haul it to the dealer? Worth noting, the last ride we had was on a murky lake and found myself in some shallows and may have took in some mud into the fresh water intake. As soon as I realized what was happening I shut it off and got to the temp gauge where it hit 205 degrees. Got it home and opened up the inpeller which had no issues and looked perfect. Ran it on the hose and found the intake side of what I believe is the transmission cooler hose clamp had come off a bit and was spraying water. Remedied that and ran boat after the inspection on the lake and boat ran at 168 as it should. Thanks for any input.

[bturner]

While 205 is hot it's shouldn't have been critical and the engine should have gone into limp mode if it were. That said and based on what you're describing, it sounds to me like you most likely, and hopefully, have a blown head gasket. Depending on how hands on you are, you could try to at a minimum try to diagnose the issue with a leak down test which shouldn't be that difficult given fairly good access to the plugs with the dividers removed.

Changing head gaskets becomes much more challenging with my biggest concern being removing the exhaust manifolds and exhaust hoses which can both be challenging even for seasoned mechanics. I've assisted with this before and I'm not sure which was worse, getting the exhaust hoses off or the rusted bolts loose for the exhaust manifolds.

If there's a bright side to this story, at least it happened at the end of the season and you have all of the off season to sort this out.....

Here's what AI has to say on the subject....

Water in engine oil due to a head gasket issue typically indicates a failure where coolant has mixed with the oil, often resulting in a milky white emulsion commonly referred to as a "milkshake". This occurs when the head gasket fails between an oil gallery and a water passage, allowing the two fluids to intermingle. Such a failure can stem from a blown head gasket, which is often caused by engine overheating or detonation.

Common symptoms include white, creamy sludge on the oil cap and dipstick, loss of coolant without visible leaks, overheating, white smoke from the exhaust, and a sweet smell from the exhaust system. If the emulsion is only present on the oil cap, it may be due to condensation, especially in vehicles that are not driven frequently, or a poorly sealing oil cap. However, if the emulsion is found on both the oil cap and dipstick, it is a serious sign of internal engine failure, and starting the engine should be avoided to prevent further damage.

Diagnosis should include checking for a blown head gasket, a cracked cylinder head or engine block, or a faulty intake manifold gasket. A pressure test of the cylinder head is crucial to detect cracks, and the engine block should also be inspected if the head appears intact. Other potential causes include a faulty oil pan gasket, especially in marine engines, or a water pump failure that allows coolant to enter the oil pan.

Repair typically involves replacing the head gasket, resurfacing the cylinder head if warped, and thoroughly cleaning the engine block and oil pan to remove all traces of emulsion. Multiple oil and coolant system flushes may be necessary to fully eliminate contamination, and it is recommended to drive the vehicle for extended periods at high temperatures to help evaporate residual moisture. In some cases, the cost of repair may exceed the vehicle’s value, making replacement or engine swap a more practical option.

[SilentSeven]

I concur with bturner but have a question.

You said

Put last years used oil in after draining and rain with the hose and the used oil came out just as milky as the previous oil change

You put old oil in the engine for the test? I likely would not have done that. Are you sure the old oil wasn't also contaminated in some manner? I would make sure to rule out oil contamination before you do any tear down. A compression or leakdown test should expose a bad head gasket. Do make sure all plugs are removed before performing the test.

Good luck!

[pdublya]

Thanks guys for the. Info. AI had me hoping it’s just the head gasket as well. As I do most of my own maintenance and am a DIY person with the help of this forum, and with it being the off season I think I’m going to leave this up to the pros.

[SilentSeven]

Everyone will appreciate the results of your mechanics investigation. Please do post.

Water in the oil is not common so it's insightful to learn what occurred.

[jpwhit]

Is there a reason now that you think it's something more than a head gasket? Was the boat used this past summer without there being signs of water in the oil? Has the boat overheated recently?

When you have water getting into an engine, time is of the essence to prevent damage from rust and corrosion. For example, if it's the head gasket and water is entering a cylinder, if it sits for long the cylinder wall will be damaged by corrosion. When I have an engine in this condition, first thing I do is take out the spark plugs and examine the cylinders with a boroscope, looking for corrosion, cracks, and water. Then I run a compression and leak down test. That'll tell you if the cylinders are still sealed. During the leakdown test, if the water jacket gets pressurized, then you know you have water entering the cylinders. If there is any sign of water being able to enter the cylinders, I go ahead and pull the heads even if I'm not going to fix the engine immediately.