Jaguar XK150
It’s the bargain of the XK range but still strong money, so buy carefully
The Jaguar XK150 is in an enticing place right now. Less hyped than either its predecessors or early E-types, yet the easiest XK to live with, a decent fixedhead coupé can be yours for as little as £34,000 if you’re shrewd about it. With the most desirable S models the other side of £100k, can this state of affairs last? Comparatively low values have meant XK150S are more likely to have been neglected though, and US cars no longer carry a premium as many have been affected by UK weather by now. We spoke to Ian Mills and Harry Rochez of XK specialist Twyford Moors, and Dan Austin of Aldridge, to help guide you towards finding a superb example of what is arguably Jaguar’s most overlooked sports car.
Which one to choose?
XK150 replaced the XK140 in 1957. Roomier and more luxurious than before, it was initially only available in fixed-head and drophead 2+2 coupé forms. The 140’s 3.4-litre XK engine was carried over, but with a ‘B-type’ cylinder head that raised power to 180bhp.
A pared-down Open Two Seater (OTS) joined the range in 1958. Criticism of 1957-model performance led to the 210bhp SE model with modified cylinder head, and triple-carburettor XK150S boasting 250bhp.
New 3.8-litre engine powered the entire XK150 range from 1959, replacing standard and SE models. Production continued until the E-type’s arrival in 1961.
Ultimate model is the triple-carburettor 1959-60 XK150S 3.8, offering 135mph and 0-60mph in 7.2sec.
Bodywork and structure
Wings rust, the lower areas in particular. The boot can fill up with water, causing rot, and the sealing panel inside the rear wings can fail, leading to rotten B-posts. Sills also rust, as do chassis outriggers and A-posts.
Look carefully for even panel gaps and shutlines. The rear wings are bolt-on and often pulled into place by their retaining bolts, which can lead to distortion. The top of the wings should have a smooth curve with bodycoloured beading where the wings meet the bodyshell. Panel gaps can be variable, with doors in particular prone to dropping when their hinges wear – but rotten A-posts and door frames create similar symptoms.
The chassis is reasonably robust but the anti-roll bar mounts are prone to corrosion and repairs can cost up to £700. The front mounts for the rear leaf springs are even more expensive to repair – expect to pay £1300 per side to get the job done properly. Replacement new chassis are readily available – albeit for around £5000 – but repairing a rotten or damaged chassis preserves a car’s originality and therefore its value.
The good news is that just about everything you need to revive an XK150 is readily available. Leaping Cats can supply a full range of panels and even a new bodyshell – for £44k-£59k depending on model.
Engine and gearbox
Both the 3.4- and 3.8-litre engines can easily last 100,000 miles if they’re properly maintained. Check for evidence of regular oil changes and that coolant has been routinely changed. A worn engine will demonstrate the classic signs of neglect – blue smoke from the exhaust at start-up and on the overrrun, and low oil pressure. The oil pressure gauge should be displaying at least 50psi at 3000rpm, although they are known for being notoriously unreliable.
A professional engine rebuild will cost at least £10,000. Poor access through the narrow bonnet aperture means getting the engine in and out is an involved affair that will set you back an additional £2000 in labour. Keeping on top of the cooling system is essential – the aluminium alloy cylinder head can suffer damage if the engine is allowed to overheat. Fitting an expansion tank and an electric fan are worthwhile modifications, but be aware that they won’t address any underlying issues.
It’s crucial to make sure the engine is what that seller claims it is. Given the premiums charged for 3.4-litre XK150SS in particular, fake examples are not uncommon. First check that engine and chassis numbers match, then look under the bonnet. A genuine S has three carburettor-mounting lugs cast into the inlet manifold, and a genuine S has its bonnet stay on the nearside, to avoid it folding down onto the more crowded triple-carburettor engine bay. Standard B-types and SES have two inlet manifold mounting lugs and the bonnet stay on the offside.
Most XKS are fitted with a tough Moss manual gearbox, which has synchromesh on second, third and
‘Less hyped than either its predecessors or early E-types, yet the easiest XK to live with’
fourth gears. The synchromesh is part of the gear itself, and was irreplaceable until Twyford Moors developed replacement parts. Layshaft and roller bearing wear is common but they can be replaced, although the bill can easily run to over £2500 for parts alone.
Beware modern five-speed gearbox transplants because parts availability varies depending on the unit fitted. Parts for the Getrag conversion, for instance, are no longer available. A Tremec T5 conversion costs more than £8000. The three-speed automatic available as an option on the XK150 is strong but tardiness when moving from second to third – along with a loud scraping noise when accelerating – suggests inner wear. A rebuilt exchange gearbox costs £2500, but removal and refitting is a big job that typically adds another £2000 to the bill.
Suspension
XK150S have rear leaf springs that eventually sag with age but it’s possible to get them retempered. There should be an inch-wide gap between the top of the tyre and the wheelarch; any less and expect to have to invest in some rebuilt springs soon.
Overhauling tired front suspension can get very expensive – just fitting a set of polyurethane bushes and replacing the various joints and telescopic dampers can cost around £2500.
Trim and electrics
Most brightwork is available new, but costs can be high and fettling is often needed to make items fit properly. Check that everything is present and in good condition; you’re often better off rechroming an original part than just buying new.
All XKS were originally positive earth with two six-volt batteries; most are now negative earth with a 12-volt battery and an alternator.
Most electrical items are readily available because they’re shared with several other classics. However, some bits – such as fuel sender units, which are also notoriously inaccurate – are costly and hard to find. Incorrect instrumentation is common because the original Smiths gauges are no longer available. As a last resort it’s possible to reface a set of Jaguar MKVII gauges, if you can find them.
Check the state of the wiring; the bullet connectors often play up as they age while many looms are now getting old and brittle, even if they’ve already been replaced once before. Electrical modifications are common and often poorly executed, leading to current
‘It’s old-fashioned to drive with its separate chassis and live rear axle, but there’s more room in it than an E-type’
drains that can be frustratingly difficult to trace and sort out. Missing grommets aren’t unusual either, and leading to chafed wires and short circuits.
Upgrades may offend marque purists, but finding buyers for a completely standard car can be difficult; just about any upgrade will add to a car’s value and make it easier to sell. Electronic ignition, a Revotec electric fan and an alternator conversion are popular and inexpensive upgrades. Electric power steering is more of a luxury – and will cost four figures, especially if you get a specialist to do the job. It makes a world of difference to ease of use though.
Roof
These can be troublesome on XK150S. The only truly weatherproof option is a fixed-head, but cars with the Webasto sunroof can leak, damaging the interior.
On dropheads, check both the fit of the hood when erected, and the condition of the wood sections in the frame. These aren’t available off the shelf and have to be made on a bespoke basis, with the wood alone costing £500 and the job of crafting it all to fit being anywhere between £500 and £1000 depending on the extent of the work required. Getting the hood to fit correctly is a tricky job best left to professionals too.