Crankcase Pressure, Oil Out the Dipstick

[jbarraclough]

Hello All<br /><br />I am at wits end here and need some engine advice badly.<br /><br />Here are my engine specs:<br />Boat is 1965 Chris Craft Constellation 37'<br />Engine is more modern Chevy Small Block 350 (slight possibility that it's a 327 too) made by Chris Craft or perhaps Pleasure Craft Marine. Stated HP is 350. Engine was rebuilt in 1998 and has had minimal use since. I would guess less than 50 hours. I do not know the details of the rebuild. <br /><br />Here are my symptoms:<br />Engine runs great up to 2800-3000 RPM. After that, I get oil spewing out the dipstick tube. I have PCV from one valve cover to the carb baseplate and another from the valve cover to the top of the carb. I also believe I have a hose coming from the oil filler tube into the carb at some point. I do not see any unusual colored or excessive smoke from the exhaust. (No different than the perfect running port engine sitting next to it.) After 3000 RPM there is a noticeable smell of burning oil (perhaps blowby). Oil is very clean - not black. Engine runs extremely strong and does not act tired or sluggish.<br /><br />Here's what I have done and my thoughts: <br />I tried to let that thing breathe in every way - replaced all PCV valves, hoses, etc. I took compression test - all cylinders had good, even compression (not more that 15 psi difference between cylinders). I have asked for several opinions and almost all are different. Rings? Sounds like it but the oil is really clean. Valve guides? I'm not burning any oil noticeably. I had one mechanic tell me to rip the engine out and tear it down. I'm not ready to give in yet so I need some good advice. If I do come to the conclusion that I need to rebuild, can anyone elaborate on last hope options such as fuel additives or oil additives or dare I say the old Bon Ami ring seat attempt (cringe, cringe)?<br /><br />Thanks in advance,<br /><br />Jeff

 

[akriverrat]

Re: Crankcase Pressure, Oil Out the Dipstick

a better mechanic than me would tell you to do a leak down test in conjunction with the compression test.i am not sure what this entails but a good mech will and it should point you in the right direction.

 

[SlowlySinking]

Re: Crankcase Pressure, Oil Out the Dipstick

jbarraclough, I doubt you need a rebuild with good cylinder pressure readings and that close together, I don't suggest the BonAmi ring seating trick. If it's not burning oil and has good power the rings are seated. It sounds like you have a higher than normal pressure problem in the crankcase which is pushing the oil out. It's usually caused by a plugged PCV system, but yours sounds like its new and clean. I wonder why you have two PCV valves, and why to the top of the carb, they should connect to the intake manifold under the carb, I suggest you disconnect and plug the one from the top of the carb and try again. Maybe return the system to what came from the factory, it can't hurt.