I have noticed a film of oil on the water after starting the engine on my boat. It is coming out with the exhaust water. It appears worse when the engine has not been run for several days. The engine temperature and oil pressure remain normal and there is no evidence of oil in the crank case. What can be the likely cause? Cracked block? Bad head gasket? Thanks for any information.
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Your valve guide seals are leaking....
Oil leaks down them into the combustion chamber after the engine is stopped. ( I do hope you have evidence of oil in the crankcase.) If it's not bad, wait until it gets worse and have the head rebuilt at that time. These seals are under the valve springs and require disassembly of the valve spring assembly to replace. On some engines you can replace them on the motor without removing the head. They use compressed air to stop the valves from falling into the engine. I don't know if this can be done on your motor. Good luck. You may also have a blow by condition.
Oil leaks down them into the combustion chamber after the engine is stopped. ( I do hope you have evidence of oil in the crankcase.) If it's not bad, wait until it gets worse and have the head rebuilt at that time. These seals are under the valve springs and require disassembly of the valve spring assembly to replace. On some engines you can replace them on the motor without removing the head. They use compressed air to stop the valves from falling into the engine. I don't know if this can be done on your motor. Good luck. You may also have a blow by condition.
correction
Opps! I meant to say no evidence of water in the crank case. Thanks for the information
Opps! I meant to say no evidence of water in the crank case. Thanks for the information
Oil sheen at startup
If you are using Marvel Mystery Oil in the gas and use a choke at startup the rich mixture will make a small sheen at startup. If your oil consumption is managable don't worry. I use a quart in 10 hours which is a lot compared to an automobile (1 quart in 600 miles in a car motor). I'm pretty sure that the oil gets past the 30 year old valve guides. The compression on my engine is strong enough to require 2 head gaskets to run smoothly. (original equipment gaskets were twice as thick as modern replacements) If I had worn rings/bores I could use just one gasket and run smooth. When I removed my engine's head I removed almost a shotglass full of carbon from the combustion chambers. That is an awful lot of carbon in the head making the compression higher than a new engine. I have installed an adjustable main jet on the carb to lean out the mixture and I have also cut back on the amount of Marvel Mystery Oil in the fuel to reduce carbon buildup. I also use straight SAE 40 Penzoil instead of 30 weight to reduce oil consumption. On a side valve Atomic Four, the valve seals are not too hard to replace if you can get to them. The valve chamber cover is under the manifold.
If you are using Marvel Mystery Oil in the gas and use a choke at startup the rich mixture will make a small sheen at startup. If your oil consumption is managable don't worry. I use a quart in 10 hours which is a lot compared to an automobile (1 quart in 600 miles in a car motor). I'm pretty sure that the oil gets past the 30 year old valve guides. The compression on my engine is strong enough to require 2 head gaskets to run smoothly. (original equipment gaskets were twice as thick as modern replacements) If I had worn rings/bores I could use just one gasket and run smooth. When I removed my engine's head I removed almost a shotglass full of carbon from the combustion chambers. That is an awful lot of carbon in the head making the compression higher than a new engine. I have installed an adjustable main jet on the carb to lean out the mixture and I have also cut back on the amount of Marvel Mystery Oil in the fuel to reduce carbon buildup. I also use straight SAE 40 Penzoil instead of 30 weight to reduce oil consumption. On a side valve Atomic Four, the valve seals are not too hard to replace if you can get to them. The valve chamber cover is under the manifold.
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