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Has anyone ever seen this weird oil sludge under valve covers? Any ideas?

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frogspeck

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After a day of slow trolling we powered up to head back to dock when engine bogged and stalled. Upon opening cover there was this tan sludge all over the top of the engine and carb. My thought is the fire suppression system went off and the boat inhaled chemical into the valve covers? I'm not sure what I'm dealing with since this was only the second time I have ever used the boat since I bought it. It was running perfect for about a day, the oil was new, any help on identifying this crud or suggestions on repair.
 

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frogspeck said:
After a day of slow trolling we powered up to head back to dock when engine bogged and stalled. Upon opening cover there was this tan sludge all over the top of the engine and carb. My thought is the fire suppression system went off and the boat inhaled chemical into the valve covers? I'm not sure what I'm dealing with since this was only the second time I have ever used the boat since I bought it. It was running perfect for about a day, the oil was new, any help on identifying this crud or suggestions on repair.
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My guess (and only a guess) is that you have water in the oil from a leaking head gasket or a cracked block or ??? What are you seeing on the dipstick?
Hopefully some of the experts will be along to give their insight.
 
DJR said:
My guess (and only a guess) is that you have water in the oil from a leaking head gasket or a cracked block or ??? What are you seeing on the dipstick?
Hopefully some of the experts will be along to give their insight.
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Yes the same tannish mud is on the dipstick. Engine has 119 hrs, 2006 Merc 4.3L. It's in the oil filter as well. I can't figure out is how it sprayed all over the top of the engine plus I have never seen oil do this???
 
I can't figure out is how it sprayed all over the top of the engine plus I have never seen oil do this???
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Ayuh,.... It's fairly common,.... it's caused by improper winterization,....

The block is cracked by ice, allowin' water to enter the oil cavity, it sprays out, 'cause there's Too much of it,... the oil, 'n water sludge,....
 
for that much, suspect a cracked block,. Usually manifolds and risers will cause some backfiring because of the water, cracked block wont and will fill everything up with that sludge looking stuff.
 
Boat has only been in freshwater lakes. I pulled the plugs and the the cyclinders are dry, no oil, spark plugs are normal. Is it simply a intake manifold gasket?
 
I know this is an old post but we had this same thing happen yesterday after 10 minutes in the water boat stalled and wouldn’t start up again. We checked the engine and this is exactly what we saw. Are there any updates to this post as to what this is and the repair process/cost?
 
That is most likely due to water in the oil.
There can be some very minor milky oil in the valve covers (which would evaporate once engine is run a temp for a hour or two) but if it looks as bad as the photo there is a good chance you may have a cracked block/heads/manifold or elbow.

Check dip stick, if oil level is higher than it should be then that may be the addition of water getting into engine. If you have run the engine dip stick may have creamy oil on it also
 
It’s water. No question. It’s either 1) cracked block or head, 2) blown head gasket, 3) cracked water passage in intake manifold, 4) failed intake man gasket. Those are pretty much the only places where there is an interface between the cooling system and the crank case. I suppose if you have an oil cooler it’s possible that could fail also. But given the pressure differential, I would not think you’d get that much water crossing that gap, unless you pumped all the oil out through the cooler and then began to take water on after you lost oil pressure. But you would get an oil pressure warning in that event.
 
Same thing happened to me yesterday. I have a 2006 Mercury Mercruiser 4.3L as well. Yesterday there wasn't anything until being out on the lake for about 3 hours. However comma today it was immediate, and didn't cease. The engine did stall, and was hesitant to start back up. All of the gauges appeared to be normal range, but the warning buzzer was going off at lower RPMs. I made it back to the dock and home safely. Now here I am. Flowing this post.
 
GotRob said:
Same thing happened to me yesterday. I have a 2006 Mercury Mercruiser 4.3L as well. Yesterday there wasn't anything until being out on the lake for about 3 hours. However comma today it was immediate, and didn't cease. The engine did stall, and was hesitant to start back up. All of the gauges appeared to be normal range, but the warning buzzer was going off at lower RPMs. I made it back to the dock and home safely. Now here I am. Flowing this post.
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The tan "sludge".
 

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Well, this thread was originally about sludge inside an engine. Having oily sludge in your bilge is a totally different issue. It is possibly just a simple oil leak from your engine into the bilge.
 
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