Mercruiser 140 from 1984 (those...)

[adruid]

1984 Mercruiser 140 #6821548 has excessive blow-by from rocker cover breather, that is so smoked with something, it chokes the engine and engine dies. Head was done 2014 and boat ran well most of last summer, till the end... I have set the carb idle at 1.5 turns, is this too rich? Engine needs a bit of extra acceleration to warm up, but that creates the toxic blow-by. I can set idle at 1000rpm fairly easily, but down at 700 it just lugs and gives up. It's as if I ran a hose from the breather out the back all would be well. (Except with the AQMD, Coast Guard, etc...) I am looking for someone with this vintage engine that has solved their problem with it. It has a Pertronix Ignitor II and a FlameThrower II coil. The peculiarities of this particular engine and the Pertronix engineers have disagreed with each other as well. Thanks for any thoughts on the matter, and Celebrations to anyone who has actually had the problem and solved it.

 

[Scott Danforth]

time to do a compression test. blow by is a product of worn rings.

 

[Rick Stephens]

Lots of times doing just a valve job will cause ring failure. Do your compression check, find out what your ring condition is.

 

[Alumarine]

There's no particular "peculiarities" with that motor.
It could be the poster child for basic, simple and straightforward.
Air-fuel, compression, spark.

 

[Rick Stephens]

There's no particular "peculiarities" with that motor.
It could be the poster child for basic, simple and straightforward.
Air-fuel, compression, spark.

Word

 

[adruid]

Yes, it is a very basic engine. My comment on peculiarities were regarding this particular engine, lower end work, and conversion to Pertronix ignition with resulting conversations. Scott and Rick's comments on possible ring issues may be critical here. Thanks!