The PCV valve is the only source of suction to provide crankcase breathing.
Remove that and don't provide anything else and it won't matter what type of
oil filler cap you use as there will be no breathing, which is bad for the
engine. Simply adding a filter to the tappet cover will allow expansion and
contraction of air inside the engine and so prevent oil being blown past the
seals, but it won't remove any condensation and you will probably find the
rocker cover getting a scummy build-up.
Originally the PCV system did not result in high oil consumption, if yours
is now then there is something wrong somewhere, which simply removing the
PCV is only getting round at best. But then again, a 73 engine wouldn't
have had a PCV valve anyway, it used continuous gentle suction from the
carbs. But if you kept the 67 carbs without the PCV ports and manifold then
you will have to keep the PCV valve as well. It could be the combination of
PCV and the later type of front tappet chest cover that is the problem, if
they are different. Are you sure the oil is coming up from the tappet cover
and through the valve into the manifold? I'd run a hose from the tappet
cover into the top of a container, with another hose in the top going to the
valve. If the container starts filling with oil then yes that is your
problem. But it is due either to a faulty valve sucking too hard, of a
faulty tappet cover allowing oil through. There should be a mesh
filter/oil-separator in the tappet cover to stop this happening.
PaulH.
----- Original Message -----
From: "MonteMorris" <mmorris@nemr.net>
To: "MG list" <mgs@autox.team.net>
Sent: Tuesday, March 09, 2004 4:51 AM
Subject: oil cap
> Our 67B has a 1973, 18V motor in it with the only pollution control being
> the PCV valve. The valve cover has a vented port at the rear at right
angles
> to the cover (I currently have it plugged). If I remove the PCV valve,
plug
> the remaining hole in the intake manifold, and put a small air filter on
the
> tappet cover pipe that once led to the PCV valve, do I now need a vented
oil
> filler cap?
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