Grand Cherokee WL & WK2 5.7 HEMI, SRT8 & 3.0 CRD

The WL was the generation that properly established the Grand Cherokee as a serious luxury SUV rather than just a dressed up off roader. Two and a half tonnes of American SUV, 364 horses from a 5.7 litre pushrod V8, a genuinely quiet cabin. On paper and in person it is a compelling thing. But that 5.7 HEMI introduced Multi Displacement System (MDS) cylinder deactivation, and that system turned out to be the defining mechanical story of this entire engine family across every generation that followed.

MDS shuts down four of the eight cylinders under light load to save fuel. In theory, clever. In practice, the lifters and camshaft lobes that carry the deactivation mechanism wear faster than the rest of the valvetrain, especially when service intervals slip or when the wrong oil grade goes in. The symptom is a distinctive top end tick that owners often wave away for too long. By the time it becomes impossible to ignore, there is usually misfire history stored across several cylinders and the cam lobe damage is done.

Exhaust manifold bolts are the other WL specific habit worth knowing. The bolts corrode into the head and snap, which leaves a ticking exhaust leak that sounds almost identical to a valvetrain tick at cold start. Getting them confused on a quick inspection is easy. We use the factory wiTECH diagnostic platform on these, not a generic scan tool, so we can read every module, run guided tests and pull proper misfire history rather than just the top level fault codes.

Routine service on a WL means full synthetic oil in the correct grade, air and cabin filters, spark plugs, drive belt inspection, and brake pads and rotors. These are heavy vehicles and the brakes reflect that. If your WL has air suspension, that system needs checking at every visit too. A Stage 1 tune is available to sharpen throttle response and torque delivery if you want more from the engine once the mechanical health is confirmed.

The WK2 arrived with a restyled body, a more sophisticated interior and a revised 5.7 HEMI producing 360 hp from 5654 cc. It also got the ZF eight speed automatic, which transformed how the car drives compared to the older box in the WL. Smoother, quicker to respond, more comfortable on long motorway runs. The transmission itself is generally reliable when it is serviced properly, but it does not like being ignored.

Here is the thing though: the engine carried over the same MDS system. Every lesson from the WL applies here. The lifter and camshaft wear pattern is identical, the exhaust manifold bolt shear happens for the same reason, and owners who do not know the history of this fault make the same mistake of dismissing the early tick. On the WK2 the oil cooler housing is an additional known seepage point, so that gets checked at every service visit. The ECU on this generation is the Siemens/Continental GPEC2A, which wiTECH reads properly with full actuation capability.

So what did the WK2 actually fix compared to the WL? The chassis, the interior quality, and the transmission are all meaningfully better. The engine got a modest power revision but the core architecture and its known habits came along for the ride. If you already know the WL 5.7 HEMI story, the WK2 is not going to surprise you under the bonnet. What it does give you is a more polished car around that engine.

Stage 1 tuning on the WK2 5.7 brings output to 380 hp and 550 Nm, a genuine 20 hp and 21 Nm improvement over stock. That is worth doing once the engine is confirmed healthy and properly serviced. Pushing a tired engine harder is not something we encourage.

Picture a school run SUV that also runs the quarter mile quicker than most sports cars. That is the SRT8 in a nutshell. The 6.4 litre naturally aspirated HEMI V8 displaces 6417 cc, runs a 10.9:1 compression ratio, and produces 475 hp and 637 Nm from the factory. The Brembo brake package up front is sized for the job. The ZF eight speed is tuned for performance shifts. It is a properly engineered performance vehicle wearing a family SUV body, and it is genuinely impressive when it is right.

The SRT8 still carries MDS, which surprises some owners given the performance focus. Same lifter and camshaft wear pattern as the 5.7, same early tick, same consequence if it is left too long. The difference is that a 6.4 working harder, running higher compression, and carrying more heat is also a 6.4 that punishes deferred maintenance more severely. The cooling system and thermostat housing are worth checking on higher mileage examples. Spark plugs take serious heat. Oil consumption if service intervals stretch. The Brembo hardware needs proper attention because with this much weight and power, brake fade from worn pads is not just an annoyance.

The ECU here is the Siemens/Continental GPEC2, and wiTECH gives us full access to every module including the SRT specific systems. Stage 1 tuning takes the SRT8 to 495 hp and 655 Nm, a 20 hp and 18 Nm gain. Given this is already a naturally aspirated engine near its comfortable atmospheric limit, those are meaningful numbers. Other options include DTC removal, a pop and bang map, start/stop disable and Vmax adjustment where applicable. We discuss what is appropriate case by case.

The 3.0 CRD is a completely different machine to the HEMI siblings. Where the petrol cars are about performance and presence, the diesel WK2 is about effortless torque and genuine range. The VM Motori A630 V6 diesel produces 250 hp and 570 Nm from 2987 cc, and it does so with a composure on the motorway that makes long distance driving genuinely relaxed. It is the pick for people who cover real kilometres or tow regularly.

The faults are diesel specific and quite different from anything on the HEMI side of the family. The most talked about issue is the oil cooler and oil filter housing. These can fail in a way that allows oil and coolant to mix, which escalates from an expensive repair to a catastrophic one if it is caught late. It gets checked on every visit. EGR valve and cooler clogging is a natural consequence of diesel combustion chemistry, especially on vehicles doing a lot of short urban trips where the DPF never gets a proper regeneration cycle. Swirl flaps and intake runner actuators can stick or fail on higher mileage cars, and crank sensor faults appear as the kilometres climb. Turbo actuator issues also show up on older examples.

The ECU is a Bosch EDC17C79, and we diagnose using wiTECH rather than a generic reader. That matters with the 3.0 CRD because proper guided tests and actuator commands are the difference between actually diagnosing a fault and just reading a code. Glow plugs, fuel filter, correct low SAPS diesel oil, air and cabin filters are all routine service items. Stage 1 tuning on the CRD delivers 285 hp and 630 Nm, a substantial 35 hp and 60 Nm improvement over stock. For a vehicle often used for towing or loaded travel, that torque gain is genuinely useful.