Jaguar XK
Published: 11th Jul 2011 - 0 Comments - Be the first, contribute now!
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Various five-speed conversions on offer if you want to ditch the okay overdrive; Toyota Supra, BMW type Getrag and the latest Mustang. Check with the supplier about parts for fitting. Jaguar did make its own for the Series 3 XJ6, which was a beefed up version of the Rover SD1 unit.
Engine
All XK units are twin-overhead camshaft, in-line six-cylinder types 3.4: 3442cc, 160, 180, 190, 210, (150S) 250bhp 3.8: 3781cc, 265bhp
Valve clearances
Inlet 0.004in; exhaust, 0.006in. (cold); the gaps are measured using feeler gauges placed between the back of each cam and the appropriate tappet. Adjustment is by selective shims. It is advisable to check the clearances every 12,000 miles; re-setting the gaps is a major head-off operation (usually along with a decoke); not for the faint-hearted!
Ignition
Firing order: 1-5-3-6-2-4 (No. 1 cylinder at REAR). Spark plugs: Champion N5 or equivalent (L7 for 7:1 low compression ratio engines). Later 3.4/3.8 litre units, Champion UN12Y or equivalent. Gap 0.025in. Check/ clean every 6000 miles or annually (whichever comes first); renew regardless every 12,000 miles. Contact points: Gap 0.014in. to 0.016in. Corresponding with dwell angle reading of 35 +/- 2 degrees. In each case, check/clean points every 3000 miles or annually (whichever comes first); renew regardless every 6000 miles. Distributor cap, rotor arm and high tension leads: Every 3000 miles, clean and check condition, ensuring that all connections are sound. Distributor:- Mechanical aspects: Every 3000 miles, remove rotor arm (checking its condition of course) and apply a few drops of engine oil to moving contact pivot, distributor shaft/cam bearing and mechanical advance mechanism (via holes in distributor’s baseplate). SPARINGLY apply grease to distributor’s cam. With rotor arm in place, feel for undue play in shaft and weak advance springs. Timing – examples (static; refer to timing marks on crankshaft pulley damper and timing case): 3.4 and 3.8 litre: 7:1 compression ratio, 0 degrees (TDC) 8:1 compression ratio, 2 degrees before top dead centre (BTDC) 9:1 compression ratio, 0 degrees (TDC)
Fuel system
Every 3000 miles or annually (whichever comes first), examine all fuel system pipework and check/top up SU carburettor dashpots with SAE 20 oil (applies to 3.4 and 3.8-litre models. After valve clearances and all ignition settings have been checked/set, and with engine fully warmed up, re-adjust carburettor mixture/ idle speed settings (use proprietary do-it-yourself equipment for synchronising carburettors, and proceed in conjunction with workshop manual). Aim for a tickover speed of approximately 500-650 rpm and 650 rpm for automatic cars (although these settings can be dependent on state of engine and carb wear/tune. Clean/lightly re-oil gauze air filter elements every 5000 to 6000 miles; renew paper types every 10,000 to 12,000 miles (or sooner if visibly dirty). If an oil bath type air cleaner is fitted, remove top cover, lift out gauze filter and clean in paraffin, then allow to dry. Empty out oil/sludge from filter housing, wipe dry then re-fill with fresh engine oil to level indicated by arrow on side of housing; re-fit gauze filter and housing lid. Clean fuel filters approximately every 10,000 miles or annually, whichever comes first (include tank filter, accessible after removing drain plug – but do this only when fuel level is very low!).
Lubrication
Engine oil: For maximum engine life (30-40lb oil pressure @3000rpm), ideally change oil and filter at least every 3000 miles or annually (whichever comes first). Ensure that oil filter assembly components are correctly installed on re-assembly (consult workshop manual for sequence). Use a premium quality, SAE15W50, 20W50 or 20W60 oil, preferably a classic blend of lubricant. Dispose of old oil in environmentally friendly manner - local councils provide waste oil collection points. Drain/refill capacity, approx: 3.4/3.8 versions: 13 pints (7.38 litres)
Manual gearbox oil: Check oil level at least every 3000 miles or annually (whichever comes first) using provided dipstick; investigate need for frequent toppingup. Use engine oil. Every 12,000 miles (approx.) drain old oil after a longrun, and re-fill with fresh lubricant. If overdrive is fitted, overdrive unit’s oil supply is shared with gearbox; to drain, remove plugs in both gearbox and overdrive unit. Every 12,000 miles remove/clean gauze within unit (accessible when drain plug is removed). Capacity: 2.5 pints (1.42 litres), or 4 pints (2.27 litres) if overdrive is fitted.
Automatic transmission fluid: Check fluid level at least every 1,000 miles/monthly (whichever comes first). Be scrupulously clean when checking fluid level and when topping-up as dirt entering the ‘box will seriously damage it. Torque converter must be full of fluid when checking level: First, with handbrake firmly applied, engage ‘P’ and run engine. Apply footbrakeand engage ‘L’; run engine at 800 rpm for approximately three minutes, then return to normal idling speed. With an assistant applying the footbrake, and with engine still at tickover, withdraw dipstick, wipe clean, then re-dip and withdraw again to check level. Top up with automatic transmission fluid if required (DO NOT overfill); difference between ‘high’ and ‘low’ marks on dipstick equates to approximately 1 pint (0.57 litres). Change transmission fluid approximately every 12,000 miles; capacity 15 pints (8.52 litres).
Final drive oil: Check oil level at least every 3000 miles or annually (whichever comes first); investigate need for frequent topping-up. Use SAE90 EP hypoid oil. Renew axle oil every 12,000 miles (approx.); drain old oil after a long run (so that it flows more easily), and re-fill. Capacity 2.75 pints (1.56 litres).
Steering/front suspension: Every 1000 miles, re-lubricate all greasepoints using multi-purpose, lithium-based grease. There are nipples on: Upper and lower swivels (assuming original types are fitted), steering rod ball joints, and steering idler unit.
Front and rear wheel bearings: Every 5000 miles, re-lubricate bearings with grease specifically stated; grease nipples are provided.
Steering: Check oil level in steering box approximately every 3000 miles/annually (whichever comes first). Note: Filler plug has hexagon head; don’t confuse with externally threaded rocker shaft adjuster screw – easy done as the unit usually gets filthy!. If necessary, top up with SAE140 EP oil.
Steering (rack and pinion): Check fluid level in gaiters every 3000 miles or annually (whichever comes first); and check for deterioration, leaks and security. On all models check the metallastic joints on the front suspension by the top wishbone mounting – it’s a common weak point although straightforward to repair if not exactly cheap.
Dampers: On the XK140 telescopic types were fitted to the rear replacing old lever arm design. Check security and leakage on both – lever types can be re-valved and sealed plus may have provision for topping up. Bounce test on each corner will show up wear (should return to static after one and a half, oscillations.
Wire wheels: At least every 12,000 miles/once a year (whichever comes first), apply grease to hub/ wheel splines to minimise wear on them. Other aspects: Every 3000 miles, check and then re-lubricate handbrake operating linkage.
Cooling system
At all times, use quality anti-freeze mixture containing corrosion inhibitors – even if the car isn’t used during the winter months. Every 3000 miles/annually, inspect radiator, all hoses and water pump/fan. At least every three years, drain system and reverseflush prior to re-filling system with fresh anti-freeze solution (observe dilution recommendations of antifreeze manufacturer – printed on container). Capacity, including heater: 3.4/3.8-litre models, 22 pints (12.50 litres).
Brakes
It least every 3000 miles or annually (whichever comes first), carry out following operations: Examine front and rear brake pads and discs, also separate handbrake components. Inspect also brake pipes/flexible hoses and master cylinder. Renew any ailing components AT ONCE. AVOID INHALING DUST FROM OLD LININGS AS THEY MAY CONTAIN ASBESTOS IF OLD NEW STOCK. Note: Early disc-braked cars used ‘rounded’ pads which required dismantling the wheel cylinders to replace. Apart from XK150, the handbrake is operated by plungers inside the wheel cylinders. Keep them clean and properly oiled for effective operation. Assess the handbrake operation and re-adjust cable length if necessary (consult manufacturer’s literature for full details or speak to specialist for advice on this). DON’T over-tighten cable or brakes will bind. Check tightness of caliper securing bolts; ensure locking wire is fitted and secure. Inspect brake fluid and check level; overhaul system if fluid is cloudy as it can mean internal rusting or failing seals. Every 6000 miles/annually (whichever comes first), clean brake servo filter (often overlooked); rinse in methylated spirits, allow to dry, lubricate in clean brake fluid and then re-install. At least every 24,000 miles/four years (whichever comes first, flush system and change brake fluid regardless of condition.
Sundry items
Every 3000 miles, or annually (whichever comes first)... Check front hub bearing condition/free play (re-adjust as required). Examine ball joint gaiters for splits. Examine fan belt and re-tension if necessary (3/4 in. deflection at centre of longest belt run). Scrutinise the clutch operating system hydraulics for deterioration/leaks. Check cleanliness and the security of all electrical connections; inspect wiring for damage. Assess condition and the security of all running gear components and suspension mounting bushes. Inspect underbody for damage and rectify any paint blemishes before winter takes hold. Check propeller shaft joints for wear/damage.
Best Mods
- Apart from a thorough service, one of the best tune ups you can give the XK engine is a good session on an engine dynometer to see if the ignition and carb settings can be improved over standard.
- Electronic ignition is worthwhile. Luminition has been a popular upgrade for a few years and does away with the points for maintenance free motoring. Prices start at £150 from Classic Spares (01992 716236).
- It is a myth that Jaguars suffer from poor cooling. If everything is in top order, then all should be well. However, in some marginal conditions it helps to have a bit in reserve. An uprated radiator is a wise step. Not only is the cooling enhanced, but with the engine driven fan removed, a few extra horses can be gained improving performance, warm up and economy. Prices start around £375.
- Polyurethane bushes have become very popular; they’re easy to fit, longer lasting and more efficient, giving a tauter feel. In some instances though, they can give a slightly jarring ride as a result. Prices start at £22.50 for a top wishbone kit. Gaz/Koni/Spax dampers offer tremendous improvements and many designs are also adjustable for finer tuning. Prices start at around £40-50.
- 3.4 engine is mainstay to range and strong. Could be better with later straight port cylinder head. 210Bhp tune is ample but you can use a 3.8 with straight port cylinder head and a pair of 420 (2in) carburettors. Triple carbs can be used, but the clutch master cylinder may have to be altered to clear third one. Apparently 4.2 S3 XJ6 top end (head and cams) is a good inexpensive mod.
- Later rack and pinion steering can be fitted but it’s a pretty involved job. Fitting later disc brakes (from XK or MK1 saloon) is much more straightforward and worthwhile – or you can use tailored kits from likes of Coopercraft which also boast more effective brake servo, too.
- Various five-speed conversions on offer if you want to ditch the okay overdrive; Toyota Supra, BMW type Getrag and the latest Mustang. Check with the supplier about parts for fitting. Jaguar did make its own for the Series 3 XJ6, which was a beefed up version of the Rover SD1 unit.
Top Tips
- Check drain hole on the fuel flap as its known to become blocked and so cause rusting at the base.
- Another rust spot are the side ventilation and heater flaps located in the front wings. Keep well lubricated or they’ll rust up and so lead to draughts and a poor heater (never that good on a Jaguar anyway).
- Rust is a problem on this model at the base of the front wings, not helped by any blocked drain holes. Check regularly and treat with a good anti-rusting agent.
- Some models have a single 12 volt battery, others a pair of 6volters in either wing at each side of the engine. Access is poor and so this leads to battery neglect. Poor starting could be excessive volt drop on the twin six system due to bad connections, deteriorating wiring etc.
- Smelly cockpit? There should be a pipe on the engine breather that carries fumes out under the wing.
- The distributor is very difficult to access on these models and best removed completely for an ignition service. Or fit a good electronic set up and have worry-free sparks.
- Electric automatic choke relies on a thermostat – always playing up so many folks simply fit a dash mounted cut out switch to isolate it if not needed. Stick throttle leading to a fast tick over can be cured simply by a stronger return spring.
- Tacho and speedometer faults can be traced to bad routed cables. Keep oiled and check cable route.
- XK engine is sturdy. but a known oil leaker, especially rear crank oil seal; an engine out job to fix properly. Keep oil between ‘min and max’ marks to lessen leak.
- Top timing chain has an adjuster; bottom rarely becomes noisy. If top one has to be replaced, an old mechanics dodge is to break chain and marry up to new one and ‘wind’ it on. Tricky but can be done.
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