Why does my Jaguar Mk2 leak oil from the back of the engine?

The XK's rear crankshaft seal is an old design that commonly weeps; because it sits at the back of the crank, curing it properly is an engine- or gearbox-out job, so many owners manage a minor leak instead.

Is an oil leak on a Mk2 serious?

A minor weep is normal for the XK; watch for leaks heavy enough to drop the oil level, oil reaching the clutch, or a sudden change — those need attention.

Where do Jaguar Mk2s leak oil?

Most commonly the rear crankshaft seal, the cam covers and the sump gasket, plus the timing cover and breather joints; most are age-hardened gaskets that are cheap to renew.

Can I fix the rear crank seal without removing the engine?

Not easily — it sits at the back of the crankshaft, so a proper cure means removing the engine or gearbox; many owners live with a minor weep instead.

Knowledge base

Oil Leaks and the Rear Crank Seal

By Jon Cosson — classic-car owner, North Yorkshire, near Thornton-le-Dale

Underside of a classic Jaguar XK straight-six engine showing oil weeping around the bellhousing — Illustrative image — not a photograph of 873 EUT; the car itself appears on the build page.

A classic Jaguar that marks its territory is almost a cliché — the XK engine leaks oil, and one spot in particular. Here is where it comes from, what matters and what doesn't.

The rear crankshaft seal

The XK's best-known leak is the rear crankshaft seal — an old-design (originally rope/scroll-type) seal at the back of the engine that weeps, leaving the tell-tale drip under the bellhousing. It is common, largely a nuisance, and — being at the back of the crank — curing it properly is an engine- or gearbox-out job, so many owners manage a minor weep.

The other usual suspects

Cam covers and the sump gasket (common, far easier to cure), the timing cover and front seal, and breather and oil-filter housing joints. Most leaks are age-hardened gaskets, cheap in themselves.

Nuisance vs problem

A minor weep is a classic-car fact of life; keep the oil topped up and an eye on it. Watch instead for a leak heavy enough to drop the oil level (and pressure), oil reaching the clutch (causing slip), or a sudden change.

Living with it

Fix the easy leaks, keep the engine clean so you can see what's new, and decide whether the rear seal is worth an engine-out cure or simply managing. If the level and the needle are falling together, read oil pressure: what's normal and when to worry.

Set-ups vary by car, so confirm any figures and procedures against your workshop manual or with the owners' clubs.

Common questions

Why does my Jaguar Mk2 leak oil from the back of the engine?: The XK's rear crankshaft seal is an old design that commonly weeps; because it sits at the back of the crank, curing it properly is an engine- or gearbox-out job, so many owners manage a minor leak instead.
Is an oil leak on a Mk2 serious?: A minor weep is normal for the XK; watch for leaks heavy enough to drop the oil level, oil reaching the clutch, or a sudden change — those need attention.
Where do Jaguar Mk2s leak oil?: Most commonly the rear crankshaft seal, the cam covers and the sump gasket, plus the timing cover and breather joints; most are age-hardened gaskets that are cheap to renew.
Can I fix the rear crank seal without removing the engine?: Not easily — it sits at the back of the crankshaft, so a proper cure means removing the engine or gearbox; many owners live with a minor weep instead.