Rockwood
Well-known member
- May 5, 2021
- 5,599
- 7,083
Discovered some fun facts/fixes about Gen III valve covers when my Jeep would make a vector control smoke screen every time I started it over the weekend after a quick day trip....
So yeah. The back-angle can be a bit of a problem with how Chevy decided to design their PCV system. If you're running original Gen III valve covers and no catch can (like me, because I hate catch cans), there's a strong chance your shit is straight siphoning oil out of the valve covers and into the intake. Why? Because GM located the drain hole on the PCV side super low in the driver's side valve cover:
With the engine angled back, lots of RPM shoving oil everywhere, and a steep hill climb or (even worse) heeled over on the driver's side, there's a strong chance that oil is pooling where where the PCV hose is located since the drain is likely submerged since GM located the oil drains at the top of the head:
on a 90* V8:
In my case, it was likely pooled enough to straight siphon out of the valve cover. Why do I think this? Because I found about half a fucking quart in my intake manifold. No pictures, but I was greeted with something like this:
When I pulled my intake off. Yes, that's pooled oil in the intake, which is tilted back 5* or so. Shitloads of oil. Everywhere.
Luckily, there's an updated part, that Dorman copied:
Amazon.com
Which has less points of entry for oil (and baffles to keep slosh to a minimum), as well as a drain hole higher up in the valve cover:
Will report back on if this fixes it, and if the gaskets that come with it are shitty. I'm fairly certain I don't have another issue as it stopped smoking once I used my Mity-Vac to suck all the oil out of there, and I left the PCV unplugged with no air puffing out indicating a blowby issue.
So yeah. The back-angle can be a bit of a problem with how Chevy decided to design their PCV system. If you're running original Gen III valve covers and no catch can (like me, because I hate catch cans), there's a strong chance your shit is straight siphoning oil out of the valve covers and into the intake. Why? Because GM located the drain hole on the PCV side super low in the driver's side valve cover:
With the engine angled back, lots of RPM shoving oil everywhere, and a steep hill climb or (even worse) heeled over on the driver's side, there's a strong chance that oil is pooling where where the PCV hose is located since the drain is likely submerged since GM located the oil drains at the top of the head:
on a 90* V8:
In my case, it was likely pooled enough to straight siphon out of the valve cover. Why do I think this? Because I found about half a fucking quart in my intake manifold. No pictures, but I was greeted with something like this:
When I pulled my intake off. Yes, that's pooled oil in the intake, which is tilted back 5* or so. Shitloads of oil. Everywhere.
Luckily, there's an updated part, that Dorman copied:
Amazon.com
Which has less points of entry for oil (and baffles to keep slosh to a minimum), as well as a drain hole higher up in the valve cover:
Will report back on if this fixes it, and if the gaskets that come with it are shitty. I'm fairly certain I don't have another issue as it stopped smoking once I used my Mity-Vac to suck all the oil out of there, and I left the PCV unplugged with no air puffing out indicating a blowby issue.
