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Re: [Healeys] FW: PCV needs fresh air too

To: Bob Spidell <bspidell@comcast.net>
Subject: Re: [Healeys] FW: PCV needs fresh air too
From: Price Lindsay <050.rpl@gmail.com>
Date: Sat, 4 Feb 2012 14:24:29 -0500
Thanks Bob!

Price Lindsay

630-841-6300 Cell
New Email Address: 050.rpl@gmail.com

Sent from my iPhone

On Feb 4, 2012, at 1:35 PM, Bob Spidell <bspidell@comcast.net> wrote:

> Basics:
>
> - an engine crankcase will always be somewhat pressurized due to blow-by
(all engines have some blow-by)
> - earlier engines--like our BN2 and my dad's '46 Chevy two-ton--have a tube
from the crankcase open towards the ground to vent the pressure (aka a 'road
draft' system)
> - a PCV system uses manifold vacuum--not pressure--to basically suck
pressure and fumes from the crankcase into the intake manifold so that it can
be (re-)burned in the engine
> - since a PCV valve is basically a vacuum leak, the valve has to mostly seal
at idle so as not to produce a lean-running condition (plus, it has to seal in
the event of a manifold backfire so as not to ignite the fumes in the
crankcase)
>
> A true PCV system will have a source for clean fresh air so the gases can
circulate, usually a tube from inside the air cleaner and sometimes from a
separate air cleaner.  The debate here centers on whether or not a fresh air
source is required.  It's definitely a good idea, but there's enough sources
of air--like leaks at the rear scroll seal or valve covers--to provide an air
source (albeit unfiltered).
>
> I'm sure you've tried to seal your leaks, with the usual lack of success.  A
PCV valve will more than likely help (although you'll want to determine if you
have excessive pressure and what's causing it).  I once tried an aftermarket
air cleaner that didn't have a decent adapter to vent the rocker and
crankcase; I ruined a valve cover trying to seal up the leaks.
>
> Bob
>
>
>
>
> On 2/4/2012 9:50 AM, Price Lindsay wrote:
>> Sorry to jump in here but I'm somewhat of a novice and am a little
confused.
>> There is talk of pressure going one way or the other after installing a
PCV
>> valve.   I've been fighting a slight leak at the real of my valve cover for
a
>> while now along with the usual drips here and there.  Here's my question:
>>
>> If I put a PCV valve in as suggested, ie from the "tee" on the valve cover
to
>> the plug in the manifold, would the pressure exacerbate the leak(s) or
>> eliminate/reduce it/them?
>>
>> Thanks for you help.
>>
>> Price Lindsay
>> 67 BJ8
>>
>>
>>
>>
>
>
> --
> *******************************************************************
> Bob Spidell           San Jose, CA            bspidell@comcast.net
>
> *******************************************************************
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