Jaguar XJ6 (X300) Power Steering Problems
On the X300 a moaning, heavy or leaking power steering is most often air or old fluid, not a dead pump: a perished low-pressure hose or a loose spring clip lets air in and the fluid froths. I'd check the level and the colour of the fluid, tighten the hose clamps and change the fluid before pricing a pump or a rack.
How bad is it · Garage, carefully
Drivable while there's fluid in it, but don't run it dry
Heavy steering is hard work, but you can still steer. Driving with an empty reservoir burns out the pump, so top up with ATF and get the leak found.
Which one applies to yours depends on your symptoms, your model year and what has already been done to it.
Likely causes, most common first
Read the check cost before the odds: a free check that rules a cause out beats a likely guess that costs money.
Air drawn in on the low-pressure side
The hose from the reservoir to the pump runs under suction. A perished hose or a tired spring clip lets air in without dripping much, and the pump starts to moan and the fluid froths.
A moan or groan at idle that gets louder as you turn, bubbles or froth in the reservoir, often with the level looking fine. Weak assist at parking speed.
Look at the fluid with the engine running: it should be clear bright red, not foamy. Feel the reservoir-to-pump hose for sponginess and damp at the pump end.
Swap the factory spring clips on the low-pressure hoses for screw clamps that bite harder, or renew a perished reservoir-to-pump hose (the dealer part lasts; generic hose can collapse). Refill and bleed lock to lock.
Low, old or wrong fluid
The system holds about a quart. Too little, tired or too thick fluid gives a moan, a heavy wheel when cold, or both.
Moan on cold mornings that fades after 15 minutes, heavy steering at slow speed, dark fluid.
Read the dipstick in the cap of the round reservoir on the right-hand front inner wing: MIN cold, MAX hot. Don't overfill.
Top up, or suck the old fluid out and refill several times. The handbook asks for Dexron IIE, with IID as the alternative; Dexron III is fine. Never mineral HSMO fluid.
Leaking rack seals
The seals at each end of the rack and at the top of the pinion tower wear out. The fluid often goes into the rack boots instead of onto the road, so the level drops with no puddle.
Topping up every few days, fluid squelching in the boots, a wet tower where the column enters. Bleeding a new pump can push old seals over the edge.
Squeeze the rack boots and listen for fluid. Rule out the cooler, hoses and reservoir joints first.
An exchange or locally rebuilt rack; 3.2 and 4.0 share MNA3890AB, the V12 servotronic rack is different and goes to a ZF service point. A seal-conditioning fluid can buy time on a slow weep.
A worn or failed pump
Running low, or a blown hose, scuffs the vanes. A weak pump makes too little pressure at idle, and a dead one leaves you with no assist and a noisy whirr.
Little assist at idle that improves with revs, a whirr or rubbing noise, sudden loss with the reservoir empty.
In neutral, raise the engine to 2,000-2,500 rpm and turn the wheel. If the assist comes back, the supply side is weak, but rule out air and fluid before you blame the pump.
A reconditioned pump; for example about GBP 360 fitted. On the six the pump drives through an adapter with a drive dog: buy it with the adapter fitted, and never press the dog onto the shaft.
A blocked filter in the reservoir
There's a filter built into the reservoir on the return side. Clogged, it starves the pump even with the tank full.
Assist that drops out for a moment, or a sticky feel at junctions after the car has stood. Moan with a full reservoir.
Take the reservoir off and look inside; back-flush through the supply outlet.
Soak and flush the reservoir, or renew it with the pump. Change the fluid at the same time.
Worn rack mounting rubbers
The rubber joints between the rack and its brackets are bonded in and not sold on their own. Once soft, the whole rack shuffles sideways as you steer.
Vague, floppy steering at motorway speed that follows the camber, a creak at low speed, an MOT advisory on the rack mounts.
Bonnet up, engine running, have someone turn the wheel while you watch the rack mounts.
Split nylon spacer rings at the mounts (SPC1059, about 3.3 mm thick) take out the play. Otherwise a reconditioned rack with new bushes.
Weeping hoses and crimped fittings
By 80-100k miles the rubber hardens and stops sealing, usually at the crimp or where rubber meets metal. The pressure line can burst.
Red fluid on hoses near the pump, at the cooler connection by the radiator, or under the reservoir. Some only leak at full lock.
Clean everything, wrap joints in paper towel and look again after a drive. Tighten every joint first.
A narrow screw clamp next to the factory band, new low-pressure hose, or a hydraulic shop to re-hose a pressure line on its original tubes.
The variable-assist connector or control module
Assist is cut as road speed rises by a transducer on the pinion housing, fed from a small control module. If the plug works loose, the rack thinks it's at speed and goes heavy.
Heavy steering some days and light on others, or heavy only when parking.
Find the electrical plug on the front of the pinion valve housing; make sure it's connected and clean. On the V12 the pressure switch is LNA1626AA: bridge its connector and see if the assist returns.
Worth trying before any parts: reconnect and clean the plug. The control module (LNA2100DB on the 6.0 V12) rarely fails.
Worn seals inside the rack
An internal seal can let fluid bypass the piston. No outside leak, but the assist fades, typically when hot and at parking speed.
Light and fine when cold, heavy at walking pace once warm, better when you rev it. A groan from the rack.
If a new pump and fresh fluid change nothing, the rack is next.
Worth considering after the cheap checks: a rebuilt rack or a seal kit.
Worn track rod ends and inner joints
Play that feels like a tired rack is often in the joints either side of it. A rack that is dry and holds its fluid is usually fine; the slack is in the track rods.
Free play or a clonk at the wheel, wander on the motorway, a knock over bumps, with no leak and no froth in the reservoir.
Wheels on the ground, a helper rocks the steering wheel side to side. Hold each outer track rod end, then feel the inner joint through the rack boot: movement you can feel is the worn one. Play at 6 and 12 o'clock on a raised wheel is the hub bearing, not the steering.
Worth trying before any rack work: new outer ends, or inner track rods, which change with the rack in place. Have the alignment set afterwards.
A binding column universal joint
The joint between the column and the rack can rust. It stiffens at certain wheel angles, not all the time.
Heavier at one point of the turn and lighter half a turn later.
Turn the wheel slowly with the engine off and feel for a notch that repeats every half turn.
Worth checking: free or renew the joint. It isn't part of a rack change.
The order to check them in
The point of the order is money: each step either rules a cause out or makes the next one worth doing. Green is free, amber costs a little, red is the one to arrive at last.
Check the level on the cap dipstick
Round reservoir on the right-hand front inner wing; MIN cold, MAX hot. Not the gearbox dipstick, and don't overfill.
freeLook at the fluid with the engine running
Clear bright red is good. Froth or bubbles mean air is getting in on the low-pressure side; dark fluid wants changing.
freeFind where it's going
Clean the pump, hoses and cooler joints, wrap them in paper towel and drive. Squeeze the rack boots for fluid inside.
freeTighten or replace the clamps
Swap the spring clips on the low-pressure hoses for screw clamps; renew any hose that feels spongy.
a few screw clampsChange the fluid properly
Suck out the reservoir and refill several times, or drain at the rack, then bleed lock to lock with the front wheels off the ground.
a litre or two of ATFDo the rev test
In neutral at 2,000-2,500 rpm, turn the wheel. Assist that comes back with revs points to the supply side.
freeCheck the plug on the pinion housing
The variable-assist connector on the rack must be plugged in and clean.
freeWatch the rack mounts
Engine running, a helper turns the wheel; the rack should not shift in its brackets.
freeRock the wheel for joint play
A helper rocks the wheel while you hold each track rod end and feel the inner joint through the rack boot. Worn joints are cheaper than a rack.
freeOnly then a pump or a rack
Reconditioned pump with its adapter, or an exchange rack. Get the alignment checked after any rack work.
an exchange unitWhat it usually isn't
Don't spend money here first:
If none of this finds it:
On jagaux.com
- Jaguar XJ6 (X300) Alternator Not ChargingIf the noise is a squeal from the belts rather than a moan when you turn.
- XJ6 (X300) fuse boxes and relays1996 and 1997 from the same page.
- Jaguar XJ6 (X300) Oil LeakIf the fluid on the floor is engine oil, not steering fluid.
- Jaguar XJ6 (X300) Steering Column and Memory Seat ProblemsIf it's the column's tilt or reach adjustment, or the memory seat, rather than the assist.
- Jaguar XJ6 (X300) Timing Chain Rattle, TensionerIf a rattle near 2000 rpm sounds like the timing chain.
- Jaguar VIN decoderConfirm your exact model year, engine and factory options before ordering parts — free.
Ratings, fuse numbers and torque figures vary by model year and market. Read the legend on your own car before pulling anything, and use the figures in the manual for your car, not the ones in a video.
Check your VIN: exactly which car you have and which bulletins apply to it.