Oil leak vs PCV system
Thread Starter
Racer
Joined: Nov 2006
Posts: 379
Likes: 7
Oil leak vs PCV system
I have put in a new 383 cui smallblock in my 1987 Corvette and have had problems with oil leaks. It startede with the valve covers, then I got better gaskets and now its the back china wall. The leaks gets worse with RPMs and "spirited" driving, which got me thinking.
I have not seen (any) blowby from the engine or such, but as I switched to aftermarked valve covers due to perimeter bolt heads on new engine, I also switched to aftermarked PCV valve and aftermarked filter/oil separator.
Unfortunately, I have not checked this when installing the engine, but both the filter/oil separator for the one valve cover and the PCV valve for the other seems very restrictive regarding air flow.
Might be a stupid questions, but would this be enough to cause overpressure in the engine and thereby the oil leaks?
I have not seen (any) blowby from the engine or such, but as I switched to aftermarked valve covers due to perimeter bolt heads on new engine, I also switched to aftermarked PCV valve and aftermarked filter/oil separator.
Unfortunately, I have not checked this when installing the engine, but both the filter/oil separator for the one valve cover and the PCV valve for the other seems very restrictive regarding air flow.
Might be a stupid questions, but would this be enough to cause overpressure in the engine and thereby the oil leaks?
Safety Car
Joined: Mar 2017
Posts: 4,204
Likes: 1,323
From: LeClaire Iowa
I don't think anyone here can give you a definitive answer as it is impossible to know how restrictive your system is. Generally, Yes if it is not free flowing it can lead to leaks. Pull the PVC out while running and see how much air flow you have. Dan
Thread Starter
Racer
Joined: Nov 2006
Posts: 379
Likes: 7
In my own opinion it's is restrictive enough to cause overpressure in the crankcase, as just manually blowing through either breather filter or PCV is difficult, so its definately not freeflowing - primarily I'm just surprised over the apparently low functional quality of the nice looking milled aftermarked PCV parts 🤷♂️ I didnt buy cheap parts.
Maybe combined with a bad seal between the china wall and intake manifold...
Oh well, off with the intake and try again 🫣 😄
Safety Car
Joined: Mar 2017
Posts: 4,204
Likes: 1,323
From: LeClaire Iowa
Yeah, I know.
In my own opinion it's is restrictive enough to cause overpressure in the crankcase, as just manually blowing through either breather filter or PCV is difficult, so its definately not freeflowing - primarily I'm just surprised over the apparently low functional quality of the nice looking milled aftermarked PCV parts 🤷♂️ I didnt buy cheap parts.
Maybe combined with a bad seal between the china wall and intake manifold...
Oh well, off with the intake and try again 🫣 😄
In my own opinion it's is restrictive enough to cause overpressure in the crankcase, as just manually blowing through either breather filter or PCV is difficult, so its definately not freeflowing - primarily I'm just surprised over the apparently low functional quality of the nice looking milled aftermarked PCV parts 🤷♂️ I didnt buy cheap parts.
Maybe combined with a bad seal between the china wall and intake manifold...
Oh well, off with the intake and try again 🫣 😄
Thread Starter
Racer
Joined: Nov 2006
Posts: 379
Likes: 7
But yes, I do plan on installing the distributor again and temporary replacing the PCV valve and the breather filter with very simple open filters - simply to check the amount of blowby (no oil filler provision) and find the exact point of the oil leak from the rear china wall, before I disassemble my 'annoying' FIRST manifold.
