APEX Steering Boost Kit with Cooler for Jeep JL and JT

APEX Steering Boost Kit with Cooler for Jeep JL and JT

Raising pressure in the steering system without taking care of temperature ends where it started: the assistance disappears, only sooner.

This version handles both at once - the pump blow-off valve retune plus a cooler in the box.

Key benefits

• retuning the factory pump blow-off valve raises the working pressure
• the manufacturer states a 40% increase in steering force
• recommended pressure 2000 PSI - which the manufacturer calls the best compromise between output and reliability
• effects listed by the manufacturer: no stiff steering in frost, smooth parking manoeuvres in heat, better feel in sand, fewer bumps fed back to the wheel, easier steering at reduced tyre pressure
• the kit does not change how the vehicle drives compared with the factory system, beyond the assistance itself
• a power steering cooler is included - the manufacturer requires one at raised pressure

What is in the box

• the pump blow-off valve retune kit: boost valve, spring with its guide and grease
• power steering cooler
• a gauge with its adapter plate and pressure tap fitting — without it the pressure cannot be set; the tap is sandwiched between the high pressure hose fitting and the pump
• five spare o-rings — supplied in case a rough install damages one

Technical data

• Manufacturer part number: X02-04-002
• Version: with a power steering cooler included
• Operation: retuning the factory power steering pump blow-off valve
• Stated effect: a 40% increase in steering assistance
• Recommended pressure: 2000 PSI
• High pressure line bolt (pump): M8x1.25x22 mm
• Vehicles: Jeep JL and JT
• Engines: 2.0L, 3.6L, 392 and diesel
• Tyres: the manufacturer states tyres up to 39" are fully covered in most cases; at 40" some resistance may appear at reduced pressure on high traction surfaces
• What it does not fix: steering play caused by problems with the aluminium steering box
• Version without cooler: part X02-04-001

Who it is for

For Jeep JL and JT owners on large tyres who want more steering assistance and want it with a cooler from the start - without assembling the job from two separate purchases and without risking an overheating system.

Installation and notes

The manufacturer provides separate installation documents for the kit and the cooler, along with instructional videos. The instructions are based on the 3.6 and 2.0 turbo engines, where the steering system is identical; on the diesel and the 392 the strip-down may differ and the manufacturer refers to the MOPAR pump removal procedure. Once the pressure is set, the gauge and sandwich plate come off and the factory high pressure line goes back directly to the pump. The high pressure line bolt at the pump is M8x1.25x22 mm.

The manufacturer warnings — read before buying

The install instructions open with five warnings, and each of them is about either money or a working vehicle.

1. The pressure limit. The factory setting is about 1300 PSI. The manufacturer recommends 2000 PSI and gives 2300 PSI as the maximum allowable, forbidding you to exceed it: going past it leads to pump or steering gear failure. The green zone on the supplied gauge is safe, the yellow one can shorten pump life.

2. The cooler is mandatory. Without one the system overheats, and that means a failed pump or steering gear. The manufacturer adds that only its own cooler has been tested with the boost valve — other types may not cool enough.

3. Temperature checks. After hard use the oil temperature has to be checked periodically. Do not exceed 300F (about 150C).

4. Systems already overheated. The manufacturer warns that a power assist system previously overheated or abused will most likely fail at the raised pressure. APEX accepts no liability for the factory power assist system — hoses, pump or steering gear.

5. The oil. The system must run high grade pure synthetic. ATF is prohibited. The manufacturer names specific oils: MOPAR 68088485AB, PENTOSIN CHF 11S, REDLINE 30404.

Installation: the pump comes out of the vehicle

This is not a job done in place. The manufacturer states in capitals that the pump MUST be removed from the vehicle, and that the valve port must face up throughout removal and installation. Otherwise the spool valve falls out, most likely gets lost, and a new pump is needed.

Before fitting, the pressure set screw is backed all the way out against the snap ring. Left screwed in, it can create a high-pressure condition before the pressure is even set, and damage the pump. The boost valve itself goes in with a 15 mm hex at 6 ft-lbs, taking care not to drop anything into the pump.

Setting the pressure is described by the manufacturer as a two-person job: one turns the steering lock to lock, the other watches the gauge and adjusts. The rule is never more than a quarter turn at a time.

Frequently asked questions

Is the cooler essential?

Yes, and the manufacturer makes it a condition: without a cooler the system overheats, and that ends in pump or steering gear failure. In this version the cooler is in the box, so the condition is met out of the carton.

Will the kit remove steering play?

No. The manufacturer states plainly that it does not fix play caused by problems with the aluminium steering box.

Will it work on 40" tyres?

The manufacturer states that tyres up to 39" are fully covered in most cases. At 40" some resistance may appear at reduced pressure on high traction surfaces - the manufacturer words it that way, not as hard ground.

Does it fit the diesel and the 392?

Yes, the manufacturer lists the 2.0L, 3.6L, 392 and diesel engines. On the diesel and the 392 the strip-down differs - the manufacturer refers to the MOPAR pump removal procedure.

How does it differ from X02-04-001?

X02-04-001 is the same kit without a cooler - there you source and buy one yourself, and the manufacturer notes that only its own cooler has been tested with the boost valve, with other types possibly not cooling enough. This version takes that problem off the table.

Why it is worth it

• a complete answer: more assistance and the cooling to sustain it
• one purchase instead of two, with the parts matched to each other

We also fit these in our own workshop - get in touch if you would like to book a slot.