[Healeys] OI. Leaks and a PVC valve engine breather system.

[Bob Spidell]

AFAIK, Norman Nock was the first to advocate for a PCV. His solution 
involved sealing the oil filler cap--I used a small sheet metal 
screw--and a seal on the dipstick to seal the tube, and venting the 
valve into the unused port on the intake manifold (Norman was an 'old 
school' mechanic willing to try new things). It's not a true PCV system 
in that there is no fresh air source, other than what can be drawn 
through the rear crankshaft 'seal' or any other leaks. I was concerned 
about the valve gunking-up or the rear cylinders sooting-up excessively, 
but neither happened in (probably) 100K or more miles on my BJ8 (photo 
of head when removed attached). You can feel significant vacuum if you 
held your hand over the filler hole at idle; and after installation my 
oil usage was cut roughly in half. When I had the engine overhauled my 
builder was adamant that he not use the crank seal I'd provided, and 
designed and built an elegant solution, still using the original valve. 
My BN2 has what I feel is excessive crankcase pressure, although it has 
excellent compression (170psi +/- on all four). I would like to install 
a system similar to what Michael S is building, but haven't committed to 
the effort yet. I'd like to know which valve is suitable for the engine 
(the one used on my BJ8 would likely be suitable, but I have no idea 
what it is).

I remember when we first became 'smog conscious,' and hotrodders went 
ballistic claiming all the 'smog shit' was going to ruin our engines, 
and the auto companies whined like little bitches. That was true, for a 
while, but now I have a 5L NA V8 capable of 480HP with 93-octane 
fuel--which I can't generally get around here--and, oh, it has a PCV 
system (and cats, etc.). I installed a catch can, and it traps about 
1tsp of oil per 1,000 miles that would otherwise end up in the intake or 
the backside of the intake valves (though it has both DI and PI so, 
hopefully, the PI keeps things clean). As far as I can tell, the PCV 
operates 'autonomously,' and I've never seen or heard of a code for it, 
but the ECU could probably tell if something was amiss with it (but 
maybe not).

Bob

On 4/4/2021 5:46 AM, rfbegani at gmail.com wrote:
>
> *How does it work?*
>
> The system is simple. The PCV valve regulates how much vacuum can pull 
> through the crankcase. It’s hooked into the intake - when the vacuum 
> is high at idle, the PCV valve stops most of that vacuum. As vacuum 
> drops with an increase in RPM, The PCV valve opens, to allow a higher 
> volume of gasses and pressure to be pulled into the intake. As a 
> result, those gasses are recirculated back into the combustion cycle, 
> and burnt off with the fresh fuel and air, preventing those gasses 
> from condensing in the oil, preventing pressure from causing the seals 
> to leak, and preventing pollution from escaping the crankcase.
>
> The breather tube allows fresh air to be pulled into the engine, after 
> the air filter, ensuring debris and moisture aren’t pulled into the 
> engine.
>
> You can read the entire article: https://tinyurl.com/drx8m62w 
> <https://tinyurl.com/drx8m62w>
>
> Note the comment preventing pressure from causing the seals to leak.  
> Regarding the Breathing Tube which we do not have on our engines, in 
> my recently installed system I plugged the breather vent in my valve 
> cover with a solid piece of rubber, although as one listener indicated 
> there is a small opening on the valve cover cap.  I will check how 
> much is flowing through this tiny hole so the engine breaths and 
> circulates air the crankcase and if it is acting as a breather tube.  
> It maybe that the T on the top of the Valve cover will need to be blocked?
>
> Ideas? Comments?
>
> Regards,
>
> Bob Begani BJ8 late 67
>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20210404/1994a833/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Cyl Head.JPG
Type: image/jpeg
Size: 1107298 bytes
Desc: not available
URL: <http://autox.team.net/pipermail/healeys/attachments/20210404/1994a833/attachment.jpe>