Classic XK Engines

The straight six dual overhead cam engine designed by William Heynes has certainly stood the test of time. Produced in various forms for many different vehicles from the late 1940’s until early 1990’s, the XK engine is testament to the craftmanship and genius of Jaguar’s former Chief Engineer.

Maintained appropriately, the XK engine has proved very reliable with these long stroke engines producing excellent torque from very low revs. SNG Barratt was founded on supplying parts for the XK engine 40 years ago and, despite some of these engines now passing their 70^th birthday, parts availability for these power units remains very strong.

As well-engineered and accurately assembled from quality parts as these engines were, we should still remember these engines were built to a price. In other words, they weren’t intended to last forever.

Detailed maintenance intervals, as defined by the factory, were essential to the longevity of the unit. That said, it is probably fair to say that its design life was not meant to exceed mileage much over six digits. In an ideal world, with all required work carried out on schedule, pretty much any component could either be reworked, repaired or replaced, and many well-kept examples can be stripped to find only minimal wear on essential areas such as the bores and crankshaft etc. It’s certainly not rare to see a mild rebore to the first oversize or a crank regrind that offers a fresh lease of life. In some cases, even standard pistons and bearings can be used. However, this isn’t always the case as many worn engines are kept running until something really breaks or the engine overheats, and the cylinder head warps, or the oil pressure gets so low that the engine seizes. Generally, if a cylinder head warps, a machine shop will be able to fix it.

Another common issue is where the steel tappet bucket guides come loose in the aluminium cylinder head and need to be retained by other means to prevent noise and excess wear. Our tappet hold-down kits offer a neat and simple to install solution whereby retaining plates are fitted and held in place with appropriately sized self-tapping setscrews, a job easily carried out at home without the need to employ a mechanic or machine shop. Oil is supplied to the head via a rigid oil feed pipe from the block, which can crack at the banjos over time. A flexible stainless steel braided hose upgrade with swaged fittings and s/s banjos is an ideal and easily installed item.

The hefty crankshaft has a large rope-type oil seal at the rear or flywheel end, and employs a standard rubber lip seal at the front or timing chain end. Often installed incorrectly, without the proper sizing tool (or not soaked in oil first, or even just old and tired), the crank seals, both front and rear, will fail at some point. Leaking oil from the crank rear seal can soak and cause the clutch to fail if the front is leaking too. But hey, if your Jaguar is leaking oil, it’s only marking its territory, right or just helping to keep your garage floor lubricated?