The rear crankshaft seal

Classic and Sports Car's buyer's guide names the rear crankshaft seal among the E-Type's leak points. Oil weeping from the back of the engine, down the joint between engine and gearbox, is a familiar sight under these cars.

Why this particular drip costs money

The seal sits at the rear of the crankshaft, behind the flywheel, with the gearbox and clutch in front of it. Nothing about the part itself is expensive. Everything about reaching it is. The engine has to come out, or the gearbox and clutch have to come off with access made another way, and either route is measured in days rather than hours. A buyer looking at a car with a damp bellhousing should price the repair as an engine-out job, because that is what it is.

Scroll, thread or lip seal

Early XK engines are widely described as using a scroll or oil-return thread at the rear of the crankshaft rather than a modern lip seal, the thread winding oil back into the sump as the crankshaft turns. Later arrangements are described as using a lip seal. The distinction matters to anyone ordering parts or judging a repair, because the two arrangements behave differently and are fixed differently.

Before condemning the seal

Oil at the back of the engine can arrive there from higher up, running down the block from a rocker cover, a cam cover or a head joint. Clean the area, run the engine to temperature and look again before deciding where the leak starts, since the upper joints can be dealt with in the car and the rear seal cannot.