donzi matt

iTrader: (1)

Before I start, I tried searching but did not find anything that really helps me much.

One of the 454/420hp motors in my 311 Formula is showing signs of water in the oil. I checked it a couple of weeks back and noticed some signs of condensation, but nothing horrible. A couple weeks go by and it appears to be getting worse. I can run my finger inside the valve cover and pull out congealed oil, and shaking out the breathers gets water droplets. The other motor, which has about 20 hours on it, is dry. The ailing motor has 650 hours on it, so I know it is time to freshen it anyhow. It has the factory Merc/Gil aluminum exhaust with Gil risers, and the engine has never seen anything but fresh water. It still runs fantastic, and aside from a routine oil check I would have never suspected a problem. I am not trying to avoid a rebuild, but would like to know what to look for when I tear it down.

I am curious what I should be looking for as a cause. The engine has not run hot at any point, around 150 degrees water temp. My boat does not have oil temperature gauges, so I don't know how warm the oil is getting. Changing the oil does not show major water contamination, but like I said, there are signs inside the valve cover and dipstick tube. I think the risers are a dry joint, but maybe I am wrong. I would imagine water passing through the exhaust would cause a misfire at idle.

Any advice from people who have seen this before would be appreciated, thank you.

Ted G

iTrader: (1)

More than likely it is a failed intake gasket right at the water port, you do have dry elbows on the exhaust.

mike tkach

iTrader: (3)

+1,but it could be reversion from the exhaust manifold,its worth checking

Knot 4 Me

Also check that the thermostat isn't stuck open.

donzi matt

iTrader: (1)

I kind of doubt reversion, the risers are about 18 inches long and mix the water at the end. Also, the idle isn't any lower than the other motor and that is showing no signs of the issue. I don't know why bad intake gaskets never occurred to me. Perhaps I will yank the intake before I pull the boat and investigate.

Thanks for the suggestions.

adk61

iTrader: (5)

what are the engines running at for temp, are they equal? if so look at the intake if not and the wet engine is running cold, it is most likely condensation, I've seen engines with as much as a qt of water in them simply from condensation issues... dont wanna make junk so better be sure

donzi matt

iTrader: (1)

Pulled the intake when I got home from work tonight. Could see a definite trail of water/milky oil near rear water port. Found the four bolts on the rear corners only slightly tighter than finger tight and water all the way up the threads of the bolts. Also found 1 bolt at the front corner of the intake under torqued and bolt threads also covered in water. No real congealed oil in the valley or on the bottom of the intake thankfully. Also, the thermostat did not appear to be stuck open, and both motors do run identical temps, around 150 degrees.

What is the best way to get rid of the condensation milky mess under the valve covers? Pulling the valve covers requires pulling the exhaust and I would rather not do that if I could avoid it. Was contemplating running a can of that motor flush through it and running it at the dock around 2500 RPM's for a half an hour or so then changing the oil again. Anybody have a better method?

Keeping my fingers crossed I can get another season out of this motor so next year I can pull both motors, freshen this one, and re cam both of them with Marine Kinetic roller grinds.

adk61

iTrader: (5)

internal flush and change the oil afterwards will work just fine....

fireboatpilot

The engine flush will help but gettint the engine temp up slightly without over heating will steam off the internal water from condensation faster and completely. Temp put in a higher temp thermostat until it clears up like a 180*

Qamar34

thanks for this post....
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