Critical Engine, BMC B-Series (1,489cc / 1,588cc)
Oil Leaks
Symptoms
Oil weeps from the rocker cover gasket, timing cover, rear main seal, and sump gasket. A layer of oil covers the engine and transmission.
Cause
Cork and rubber gaskets deteriorate over decades. The B-series rear main seal is a scroll-type design (early engines) or a lip seal (later engines), both leak eventually. The rocker cover uses a cork gasket that compresses and loses its seal with repeated removal.
Fix
Replace all gaskets systematically.
Use modern gasket materials where possible.
The rear main seal requires the engine or gearbox to be removed.
A complete engine reseal: $300-$600 in parts, $500-$1,000 in labour if paying a workshop.
Cost mentioned in fix
$300-$600 in parts$500-$1,000
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