Detroit 471 super charged

hello i have a customer with a

hello i have a customer with an old displacement boat 1936 with detroit 471 dry exhaust water cooled muffler keel cooling it has just started blowing bit of oil out of exhaust. oil analysis came back fine removed covers checked rings and cylinders look. ok blowby not bad he does nurse it around a bit any ideas was reconditioned 5 years ago

"If the rings aren't passi

"If the rings aren't passing the oil, that pretty much leaves the blower seals as this engine doesn't create vacuum to suck oil down the valve stems. The blower will deliver oil to the combustion chambers and you can see that as it washes on the rotor lobes. Open the the intake, remove the screen, clean the lobes and then test run. It should show pretty quickly.

The only other thing I would want to know is if he has a tendency to run the oil level too high or uses multi-viscosity oil. These are mono-viscosity oil engines except in the coldest of climates."

after trying that. if its not

after trying that. if its not the blower you can check your valve guides by taking the exhaust manifold off and look at your valves to see if there covered with oil. valve guides leak oil when they are worn out.no need for a vaccum it can drip along the valve.

"Mikey's right. However, i

"Mikey's right. However, if the complaint is that the engine smokes all the time I would point out that the 71 series 2 cycle combustion chamber is always positively pressurized while the engine is running. Compression, combustion, exhaust and blower supplied air all serve to keep a very positive pressure within the cylinder. If the complaint is that the engine smokes on start up and then it stops smoking after a bit then that would indicate oil draining down valve stems while the engine is stopped."