Overfilled oil level in crankcase

[CC Searay 81]

I accidently overfilled my 1980 260 Mercruiser with about a quart too much oil! Before I knew it, I took the boat out and
ran fine for about 10-15 minutes. Then it felt like it didnt have the power. Limped back to trailer. Replaced cap rotor plugs wires. Still loss of power. I started pulling plug wires from cap 1 at a time and found 5 & 7 did not change on or off! Then I pulled the valve cover on that side and found a foamy moisture looking film all over everything! But when I pull the dip stick the oil is clean and clear? I found out through reading threads there is suppose to be a water shutter in the bottom of the Y pipe to keep water from being forced in exhaust by fast stops! If my water shutter was malfunctioning or gone, could I have sucked water up in the back two cylinders 5-7 on that side? or is the cream looking film all over the head from too much oil in the crankcase?
Motor is not noisy or rattling? Thanks in advance to anyone with some insight on where to go from here? :smt100

 

[rusobr2]

cc searay 81--this is only my opinion ! 1 qt. extra is really not that bad. if you stretch that qt. of oil over the entire pan area,(witch is at the greatest area in sq. in.)its only about 1/4-3/8 extra in height.problem is the rod ends come around and slap the oil-kinda like an old model a ,that had to slap the oil in order to get the pickup cups to feed the rod bearings--little usage should not have hurt the motor--did you notice if your engine oil press. gauge changed at all---
the problem in the valve cover is a water oil mixture--if the water came in the exhaust port --the valves opened up,and the piston pushed the water into your valve train,but as this has to return back down to the pan,i can't figure out why there is no milky substance in the pan--unless it was only a super small amount,and you are dealing with one small area only--pull oil filter ,and check it to make sure no milky oil in it.i don't know what else to say until there is some items checked--

steven

 

[andy richmond]

If the shutters are bad you can get water in all of the cyliders.Pull the plugs and make sure.I just lost a 260 because of shutters.

 

[stevea661]

The dip stick does not go the the bottom of the pan. Crack the oil drain plug and see what you have. Water will make the oil level appear to rise. Oil floats on water. The water is in the bottom of the pan. Sorry.

 

[CAGE RATTLER]

I was told that to much oil will cause the oil to foam due to it being stirred up to much but not sure how that would make 2 cylinders not to fire.

I 2nd the opinion to pull the plugs to make sure there is no water in the cylinders and also check to make sure no water is in the oil pan.

 

[KRB64]

Could you have blown the head gasket between 5 & 7? Cracked the head? Something is going on between those two cylinders and mayb you just haven't run it long enough for it to affect the rest of the oil yet?

 

[Daddubo]

You have a cracked head or blown gasket. Did any of the plugs have water in them?
I cracked the heads on mine and the oil level did not go up but when I took it a part there was foamy gunk through out the top end. Milky crap in it that is a sure sign you have water in the engine. I went to do a compression test on mine and it spit water at me, so pull the plugs and turn it over and see what happens.

 

[Daddubo]

Another thought check the intake I had an aluminum intake on a 86 K20 and it would keep loosening up on me and when the engine was rebuilt was a sealer used on the head bolts that go into the water passages?