[DMCForum] Re: PCV Routes Manifold Vacuum Through The Crankcase

["content22207" <brobertson@xxxxxxxxxxxx>]

Actually, if your engine is equipped with PCV, yes there is. How do
think those vapors get into the combustion chambers? They don't
radiate in of their own accord.  Please reference paragraph 4b Page
D:06:03 of the Workshop Manual: "An air leak in the engine crankcase
will cause a lean running condition since the crankcase is connected
to the intake manifold" (JZD's words, not mine). Traditional PCV sucks
air in one side, passes it through the engine, then out the other into
the manifold.

PRV is unique in that there's no sensible path from #1-3 valve cover
to the manifold connection. What I once thought at a glance might be
crossover passages through the intake manifold are actually holes for
locating studs -- my 7ZV has empty holes in the manifold and heads but
no studs (you can see the holes are bottomed if you bother to look
stright down into them). My new B28 does have studs in the heads, but
nothing in its smaller intake for them stick into. Go figure. Near as
I can tell, vapors from that side of the engine are sucked through the
timing chain cover and oil return passage to #4-6 valve cover. Which
conveniently brings us to this morning's history lesson:

My car came with a terrible vacuum leak. PO had gotten the poor thing
to run by dialing up the fuel mixture (which is what probably doomed
the catalytic converter, killed my fuel economy, etc). I traced the
leak to the upper #3 end of the engine. Would kill it if you hit it
with a steady stream of carb cleaner. One of the things that threw me
was you could kill the engine by spraying the valve cover/head mating
surface (what was in fact happening was carb cleaner was running down
the machined manifold mating surface and getting sucked up from
below). Why did that throw me? Because...

About this time Rich Acuti was having his original coolant leak
problems. Pointed us all to previosuly mentioned Page D:06:03 of the
Workshop Manual (remember all the Brother Maynard quotes) which I
repeat clearly states: "An air leak in the engine crankcase will cause
a lean running condition since the crankcase is connected to the
intake manifold" (duh). Remember also my PCV was rigged up like B27 --
sucked through both U pipes. It ain't fooling around. Hold your finger
over the breather hose and the engine emits a loud moan then dies. 

The culprit ultimately turned out to be an unused wiring harness
connector sandwiched between the coolant distribution pipe and the
bottom of the intake manifold, preventing it from seating properly.
Couldn't see that from above. Yet another advantage of that rediculous
K Jetronic setup.

Since your engine is running so well, I will refer all future
technical questions to you (Sorry Dave Delman). And Jim Strickland,
who once had the audacity to state that higher compression *LOWERS* HP
(why didn't anyone jump all over him for that?). And Martin who
insists the DeLorean is perfect as it left the factory (Message
#16339, replying to my Message #16324). And of course the Everlasting
Knowitall (CheckSix3).

There is going to be so much butt kissing going on, I suggest you all
form two lines. One line can kiss one cheek while the other is kissing
the other. I'll put a jar at the front for donations to Farrar's
DeLorean purchase fund.

Bill Robertson
#5939

>--- In DMCForum@xxxxxxxxxxxxxxx, "Walter Coe" <Whalt@xxxx> wrote:
> Okay, 2:30AM and I'm buzzing, so I can't let this one go...
> 
> > Can I ask a silly question:
> 
> Sure.
> 
> > Why do people give me all this crap for installing an
> engine that was
> already carbureted from the factory, then turn right around
> and lament
> all manner of starting & running problems with their own
> blocks?
> 
> Because you give people advice that is peculiar to your
> unique non-stock configuration while this advice is totally
> wrong for someone trying to repair a stock configuration.
> And what makes it really bad is that too many people don't
> know the difference.  You have done this many times -- in
> fact every time you mention vacuum leaks in your crank case.
> There is supposed to be no vacuum in the crank case of the
> DeLorean version of the PRV.  Period. (.)
> 
> None the less, we love you anyway Bill.
> 
> Walt    Tampa, Florida

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