Engine Breather - Bypass - oil leaks

I have a question about when you disconnect the Engine
Breather from the valve cover to the Intake (before TB).
Since there is a vacuum to the engine block (during
throttle open) would it be possible that a loss of this
vacuum to your engine could result in slight oil loss
through once before unrecognized leaky seals...?

Yes it is.  Ahhhhh so the breather tube is minimal by comparison then...??      But wouldn't disconnecting one counteract the affects of the other...?

I am not convinced that this should be disconnected.

As is mine. I'd leave her be, Kevin.

Short of rebuiding the engine, sounds like an oil catch-can installed in-line with Kevin's breather hose is the route to go then.

I made a catch-can years ago and used it on a 1970 Nova that was puking copious amounts of oil into the air filter housing. Worked great.

 

Romeo wrote: As is mine. I'd leave her be, Kevin.

I tend to like leaving factory designed stuff alone
especially with engines - you would hope that engineers
are
paid the big bucks to do things right - and yes at the
same
time I agree some stuff can always be improved (but does
one improvement justify the potential detriment of
something else...)

Cheers!

Oh and we sort of got off topic here. I was more
concerned about the Crankcase vacuum state as opposed to
free air state and how this may affect oil seal leaks.
Anymore theories on this matter would be appreciated

Another thing you can do, is stick the K&N back in there, then wrap a wrist sweat band around it.If you still get too much smoke after that - you've simply got SUCH a worn out engine, it's time for new rings (etc) anyhow.

As for the question of engineers getting paid the big bucks to do it right...  well...   they DID.  Then the engine kept running for ANOTHER 20 years past it's normal usage and it wore out.  Simple.

Regarding the crankcase being under vacuum.  That's where it normally is (well, is supposed to be) when it's running right.  As the thing wears out, the blowby exceeds the PCV's capacity to pull one.  I mean, we're not talking 15" of mercury or anything here (while you might see 20" in a high end race only engine).  It might be 1 or 2".  Just enough to keep the crud in the air being pulled out. 

Easy test - pull the breather out.  Stick your thumb over it, and rev the engine to about 1.5-2K and hold it.  Thumb get slightly pulled in after about 30 seconds?  You're probably OK.  No pull?  Worn out.

kharmata wrote: Not sure if this completely minimizes suck on the bad rings...

Honestly, there is not enough "suck" on that breather tube to affect crankcase vacuum at all.

It's the other tube, the one that's connected to the PCV valve and the intake manifold that supplies all the "suck".

 

kharmata wrote: With the breather open to free air the pcv will never provide any vacuum to the crankcase...or am I wrong here?

It sounds to me like you've got it wrong.

The intake manifold is sucking air from the crankcase (through the PCV valve) whether you've got the other breather tube connected in front of your throttle body or not.

The following is taken from Here.

SYSTEM OPERATION:
The PCV system prevents blow-by gasses from entering the atmosphere by routing blow-by gases into the intake manifold through a vacuum controlled ventilating valve and a hose while allowing proper crankcase ventilation.

Blow-by gases mix with the air/fuel mixture and are burned during combustion. When the engine is running, fresh air is drawn into the crankcase through a tube or hose connected to the air cleaner housing.

This system is still the same as it was when it was first used in 1961.

PCV VALVE OPERATION: The PCV valve consists of needle valve, spring and housing. When the engine is off: the spring holds the needle valve closed to stop vapors from entering the intake manifold. When the engine is running: manifold vacuum unseats the needle valve allowing crankcase vapors to enter the intake manifold. In case of a backfire in the intake manifold: the valve closes, stopping the back flow and preventing ignition of fumes in the crankcase.

During certain engine conditions more blow-by gases are created than the ventilator valve can handle. The excess is returned through the air intake tube to the air cleaner and carburetor where it is burned in the engine.

A quick check of the system can he made by pulling the end of the PCV valve out of the valve cover and placing a finger over the end of the valve to block the air flow, while the engine is idling.

• A vacuum should be felt and the engine speed should drop approximately 50 rpm if the system is satisfactory and no further testing is necessary.
• If there is no change in engine speed a clogged system is indicated, proceed to the next step.

To isolate the problem, remove the PCV valve from the hose and note vacuum felt and any change in idle speed.

• If the ventilator hoses and carburetor passages are clear, a strong vacuum will be felt and the engine idle will change drastically or the engine will stall when the end of the hose is uncovered. If this occurs, the trouble is in the valve.
• If the engine continues to idle approximately as it did before the hose was uncovered, the hoses or carburetor passages are blocked.

As for the other end, the air intake side, there is little that can go wrong. As long as the hose or breather filter is not clogged, air has to enter the system.

-------------------------------------

Kevin, I've indicated in red the part that especially applies to your situation.

 

kharmata wrote: Patrick, I get that part. But internally (crankcase) are they not both opening into the same big space (crankcase)...? I think our perspectives are slightly different here. (In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure) Yes I get this part.

I've added to my earlier post to try and make my point(s) clearer to you.