blow-by

[1985xjlaredo]

OK this is what I ended up doing:
First Change the old valve cover! It had these baffles that had metal tubes running down about 3/16th's of an inch from the bottom of the cover! (no wonder it was sucking and spewing oil!)
Then I installed a normal PCV valve and some 5/16" fuel line to the petcock of the intake manifold.
Lastly I took off the Hose that runs to the air box and just put a Mr. Gasket 2057 Valve cover breather on there. PICS:

I thin That It looks kinda good on there and I haven't had a drop of oil any where since I changer it 2 days ago. Oh and I re torqued all my rocker arms, It is a lot quieter now too.

 

[Ecomike]

Have you replaced the CCV tubing? Should be done periodically. It won't eliminate 100% of the blow-by, but it will reduce the oil in the air cleaner considerably.

I think some people are misdiagnosing this problem as blow by. In my case replacing the valve cover gasket, getting and keeping it tight, replacing all the valve cover seals (rubber) on top and getting them all air tight, and cleaning or replacing the small diameter CCV tubing that gets clogged up as well as the small orifice (2.2 mm is the Renix spec) in that line at the valve cover connection (replace or eliminate, I have tried both) eliminated all the oil getting into the air filter and the larger diameter breathing tube that connects the air filter to the valve cover.

Mine has 245,000 miles on it. What happens is that if there is any place on the valve cover where air can leak into the upper engine/valve cover area then the small ccv tube sucks air in from there (less resistance) instead of sucking it in from / through the larger air filter tube. Thus oil vapor can get into the larger tube since it sees some engine vacuum (as it is on the normally clean side, lower pressure side of the air filter), then it condenses and runs backwards into the air filter assy.

 

[AlabamaDan]

OK this is what I ended up doing:
First Change the old valve cover! It had these baffles that had metal tubes running down about 3/16th's of an inch from the bottom of the cover! (no wonder it was sucking and spewing oil!)
Then I installed a normal PCV valve and some 5/16" fuel line to the petcock of the intake manifold.
Lastly I took off the Hose that runs to the air box and just put a Mr. Gasket 2057 Valve cover breather on there. PICS:

I thin That It looks kinda good on there and I haven't had a drop of oil any where since I changer it 2 days ago. Oh and I re torqued all my rocker arms, It is a lot quieter now too.

Nice engine and fix. Where'd ya get that valve cover?

 

[Ecomike]

Has that open vent on the Valve cover and the PCV valve combo affected the idle speed at all????? I have recently noticed that the Renix engines are very sensitive (affecting the idle speed) to excess air flow or persieved vacuum leaks from the CC ventilation system, which would include modifications like yours. The OEM Renix version (the one I know) has a precise 2.2 mm orifice in the small CCV line (3-4mm dia) leading to the intake manifold. I would think the PCV valve opening and closing might change intake vacuum enough to confuse the Renix computer sooner or later.

We would be interested to know if you notice any idle, or acceleation issues, or changes in performance the next few days or weeks.

Also I would be interested to know if your PCV valve and larger vent line starts feeding oil to the intake manifold and consuming significant amounts of oil?????

 

[thederrick106]

I think some people are misdiagnosing this problem as blow by. In my case replacing the valve cover gasket, getting and keeping it tight, replacing all the valve cover seals (rubber) on top and getting them all air tight, and cleaning or replacing the small diameter CCV tubing that gets clogged up as well as the small orifice (2.2 mm is the Renix spec) in that line at the valve cover connection (replace or eliminate, I have tried both) eliminated all the oil getting into the air filter and the larger diameter breathing tube that connects the air filter to the valve cover.

Mine has 245,000 miles on it. What happens is that if there is any place on the valve cover where air can leak into the upper engine/valve cover area then the small ccv tube sucks air in from there (less resistance) instead of sucking it in from / through the larger air filter tube. Thus oil vapor can get into the larger tube since it sees some engine vacuum (as it is on the normally clean side, lower pressure side of the air filter), then it condenses and runs backwards into the air filter assy.

That is the truth, everything needs to be air/ oil tight...