Valve cover venting

[rrc0]

New to me 2001 3.0 liter GSM-A with 118 hours. My first sterndrive. Please help me understand valve cover venting. Front hole PCV - valve rattles when shaken and has strong suction. Rear hole rubber hose to spark arrester. When pulling that rear hose with engine running, there is air blowing out. Shouldn't that be sucking air in? Is that a classic danger sign of engine blow by? Seems strange with a low hour engine. Please advise this newbe.

 

[alldodge]

If I understand you correctly, the PVC is removed from the valve cover while the motor is running and your seeing vapor come out.

If correct, then yes that is blow-by and all motors have it, but if there is enough that the PVC is not taking care of it then its gotten pretty bad

 

[rrc0]

The PCV valve is in place and working correctly (good suction). I pulled the rear valve cover hose (that leads to spark arrester). You can feel air blowing out of that hole. Shouldn't that suck in air? Is that blow by and a sign of a badly worn engine? New purchase and feeling pretty worried. Would you expect that on a 118 hour 3.0 liter engine? Am I overlooking somethiing?.

 

[alldodge]

With PVC in place and sucking, and also feeling it come out, then yes that sounds like a worn motor

With 118 hours for a 19 year old motor it has sat a long time. Give it some run time and fresh oil change. Could be with some running the rings will re-seal and you will be fine. Don't do any WOT runs, just give it some good cruise time for maybe the first 5 hours before you start getting in to it

 

[rrc0]

Thanks for the reply. Is there anything else I can do to "encourage" the rings to re-seal? Marvel Mystery Oil or Rislone thru spark plug hole into the cylinders? Would this blow by explain the oil foam mocha around the carb and why I can't get it to idle smoothly?

 

[alldodge]

Different issues
Foaming oil, if it is milky then you have water in the oil
With a bad idle could be many things. Combine milky oil and good chance of a blown head gasket, cracked block or other

Run a compression test

 

[rrc0]

Appreciate the help! The oil in crankcase is clean - not milky and no smell of gas. But I did note some milky oil around carb base after use. Thought maybe it was blow by being pulled in from rear valve cover vent thru carb. Will do a compression test. All plugs out, WOT, dry then with squirt of oil. Numbers should be 100-150 psi correct? Are those wet or dry numbers?

 

[alldodge]

Yes
Your look for 150, and 100 is minimum. If your dry and get close or at 150 then no need for wet. The wet is only if there is a low cylinder to see if it will come up

 

[rrc0]

Until I can provide the compression test results, is there anything I can do to "encourage" the rings to re-seal? What is the current thinking about Sea Foam in the crankcase or Marvel Mystery Oil in the cylinders? Not really familiar with the concept of rings re-sealing. Any additional info greatly appreciated for this newbe.

 

[alldodge]

There isn't a mechanic in a can, most IMO is snake oil
If your not getting water in the oil (said your not), just run it and have some fun. It should slow to a stop, and if it doesn't your not hurting anything from what your saying