The usual problem is hardened rubber washers under the domed cups under the
fixing nuts. It is only the compression of these which pushes the cover
onto the gasket and the gasket onto the block, not the tightness of the nuts
as one might think. The nuts themselves are deep and tighten down onto the
rocker pedestal, so they cannot (on their own) distort the cover. However I
have still had leaks after replacing both washers and gasket, I think the
cork gaskets are just not as thick as they used to be, I had to put packing
material between the rubber and cup washers before I could get a seal.
Early cars had a 'non-positive ventilation system which consisted of an open
pipe on the front tappet cover and a pipe from a vent at the front of the
rocker cover to the front air filter. In 64 a positive system was
introduced with a PCV between the inlet manifold and the front tappet cover
with a filtered and breathing oil filler cap, the original vent being
blocked off. By 1969 the PCV had gone from UK cars and a port from the
carbs sucked on the front tappet cover, the breathing oil filler cap being
retained. 1n 1970 North American cars got a carbon canister connected to
the restricted port at the rear of the rocker cover and the filler cap
became non-breathing.
----- Original Message -----
From: "John Graham" <theklube@hotmail.com>
To: <mgs@autox.team.net>
Sent: Thursday, June 12, 2003 12:13 PM
Subject: MGB - 1970 Rocker Arm Cover Leakage
> Now that I'm beginning to drive the beast again, I'm looking to fix things
> that I never got around to before - oil leaks in the engine area. From
what
> I can observe, my leaks are coming from the rocker arm cover area. I'm
> planning to renew the gasket there, but in looking at the situation, it
> appears that some leakage may be coming from the area of the front bolt
> holding the cover down.
>
> This got me to wondering if there might be a pressure situation in the
> crankcase that was forcing oil out. I looked the top of the engine over
> (it's a 1970) and I didn't see any form of crankcase venting arrangement.
> There's a little tube coming out of the back of the cover which is stubbed
> off, but I believe that to be stock.
/// or try http://www.team.net/cgi-bin/majorcool
/// Archives at http://www.team.net/archive
|