Smoke from valve cover / breather hose SBC 305

[bollerwagon]

this is my fresh water cooled interim-engine, a 5.0 volvo penta V8 sbc engine.
While this didn´t happen with my old engine, there is a lot of smoke coming from the flame arrestor when in idle. Plugging off the breather hoses, you can see the smoke coming out. When I open the caps in the valve cover, it looks white inside and there is a lot of smoke coming out. The video was done in idle, no heavy lifting before. After a faster fun, it smokes even more.

Is this supposed to be, or what kind of problem am I looking at here?

 

[alldodge]

Blow by, rings not seating
YOu said it looks white under the valve covers, do you mean like milky water?

 

[bollerwagon]

No milky water, that was badly explained. Oil looks good too, if I pull the dip stick.
But when open the valve cover cap there is very dense mist. If you leave it open for a while it clears up a bit and you can see the rockers work.

Edit: just googled the "ring" hint. So it is the piston rings that leave too much oil on the cylinder walls? Before I installed it the engine was sitting for a long time and didn´t run. I filled it up with mineral engine oil and was recommended to do a oil change after 10 hours or so. Might that be a temporary issue caused by the long sitting period and/or the oil?

 

[alldodge]

Piston rings, the pistons have 2 compression rings and 1 oil ring. When the compression rings get weak or damaged, they start allowing combustion pressures past them. This is called blow-by because the pressure blows by the rings and into the crank case. The pressures which wind up in the crank case escape out the valve cover vents

 

[bollerwagon]

Thanks for clarification.

There is not much pressure when I hold the tubes with my finger or shut the valve cover with my hand. Still blow by gas? I would expect them to expand more violently when they have the chance.

 

[alldodge]

Inside the combustion chamber there is lots of pressure every time the spark plug ignites the fuel. Some of those burnt by products is what your seeing as it mixes with oil vapors. Pressures increase as motor temps come up and speed

 

[bollerwagon]

so can I fix/improve this with different oil? Or do I have to change piston rings?

 

[Lou C]

There will always be some blow by as seen by the need for crankcase ventilation and on motor vehicles the adoption of positive crankcase ventilation valves. The question is how much is too much. I think if you get some smoke there but the engine doesn’t consume excessive oil I would not concerned. If it does then you have to decide if repairing it is worth it or just keep adding oil so it never gets low.

 

[alldodge]

^^ Agree
Don't know of a mechanic in a can. Some try marvels mystery oil or others trying to free up the rings. Most don't work IMO but as Lou said

 

[bollerwagon]

that sounds reasonable. I was just worried, since this is a new phenomenon.

Also, after some higher rpm runs (2-3000) it looks like smoke is coming out of the intake manifold gasket, have not yet figured out where exactly it comes out.
Will do some investsigation in that soon and maybe update this post.

 

[Lou C]

Mine does this as well at idle after warming up but it doesn’t get worse when running at higher rpm. The engine does consume some oil but it doesn’t foul plugs at all so I just live with it for the time being.The short block on mine is original 33 years old, reman heads installed 4 years ago. If it was burning a lot of oil and fouling plugs it would make sense to think about a rebuild if the engine was freshwater cooled.

just make sure you don’t see milky oil inside the valve covers that suggests water in the oil from a blown HG or other engine problem.