Over recent months I have had a very slight oil leak from the rocker
cover area. Not enough to drip on the floor, but enough to be
visible. Fixing nuts were tight, so eventually replaced cork gasket,
no change. Put a thin smear of gasket stuff on both sides of the
gasket (plus thin smear of oil on head and cover to stop bonding the
two together), no change. Bought a new gasket and tried again, still
no change.
Prodding the gasket showed that even though the rocker cover nuts
(really a bolt with a tapped sleeve on the head) were bolted down
tight the gasket was still a sliding fit between cover and head.
This is because the tapped sleeve on the fixing nuts tightens down
onto nuts on the two longer rocker fixing studs (still with me?) and
not via the cover and gasket. This stops overtightening which can
squeeze the gasket out of position (but inside the cover so you can't
see it) and make the leak even worse (as I found out when I tried
fitting extra thick washers between nut and cover).
There is a thick rubber washer fitted between the domed metal washer
(under the nut) and the cover, and I presume that over the years this
has compressed and hardened to the point where it no longer puts
sufficient pressure on the cork gasket. Moss show them as available
so I shall try new ones, but in the meantime have padded the existing
ones out with flat washers cut from diff-cover gasket card. The back
needed three thicknesses and the front two before the cork gasket was
held against even gentle pressure.
PaulH
73 Roadster (HD&H)
75 V8 (DD)
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