How Do I Check Crankcase Pressure In 15HP Johnson ... also, F_R mentioned

bobgritz

Petty Officer 2nd Class
Joined
Sep 22, 2009
Messages
185
I am replacing head gasket on my 15 horse Johnson but in a recent post, F_R mentioned 'crankcase pressure' and I have always been curious of the procedure to check this (and what is the acceptable range). I was tempted to replace the exhaust gasket too and wondered what the procedure is and how does one gauge if, in fact, it needs to be replaced?
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: How Do I Check Crankcase Pressure In 15HP Johnson ... also, F_R mentioned

If you are getting water in your cylinders or on your plugs it may be from a faulty exhaust gasket.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: How Do I Check Crankcase Pressure In 15HP Johnson ... also, F_R mentioned

Crankcase pressure is only about 4-5psi, running. Only practical way to check it is to turn it over with the plugs out and listen for the "plop-plop" sound as the ports open.
 

boobie

Supreme Mariner
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Nov 5, 2009
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20,826
Re: How Do I Check Crankcase Pressure In 15HP Johnson ... also, F_R mentioned

Is "plop-plop" a new troubling shooting term ?? Just curious.
 
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