Dodge repair and servicing in Sharjah

Cylinder deactivation on this engine works by collapsing a special lifter with oil pressure, and when one of those lifters fails it wears the lobe it sits on. That makes the noise and the misfire the same fault. We record misfire counters per cylinder rather than trusting one stored code, move the coil and the injector to another cylinder to prove the fault does not follow them, listen bank by bank hot and cold, and take a compression reading on the suspect cylinder to see whether the valve is opening as far as it should. Oil condition and level are part of the diagnosis, not a side note, because the deactivation hardware runs on oil pressure. If the lobe has gone the camshaft and the lifters are one job and we say so before anything is opened, because that is not a repair to discover halfway.

This is the noise that gets a HEMI condemned as a lifter engine when nothing inside it is wrong. A manifold bolt that has snapped lets exhaust gas escape at the flange, and the gap closes as the metal expands, which is why the tap is a cold-start noise that fades. A lifter tick does the opposite: it stays, and it usually brings a misfire with it. We listen at the manifold flange with the engine cold, look for the soot trace that a leaking flange leaves on the head and the manifold, count the studs that are still there, and check whether the misfire counters show anything at all. That last check is what keeps an engine from being opened for a bolt.

That narrow band of speed and throttle is where the converter clutch is asked to hold with the least help, so a clutch that is slipping shows itself there and nowhere else. We road test with converter slip, commanded lock-up state and fluid temperature on the screen at the moment it happens, because a shudder felt at that speed is also produced by a misfire and by a wheel out of balance, and all three feel identical from the seat. Misfire counters are read in the same test so an engine fault is not sold as a gearbox. If the slip is real we say whether it is the converter or the control that is asking it to slip, in advance of any strip.

A rear-drive car driven hard on hot tarmac puts more into its axle than the fluid interval assumes, and the hum from a pinion bearing that has been running hot arrives long before anything breaks. We road test to establish whether the noise follows road speed or engine speed and whether it changes on and off the throttle, which separates a differential from a wheel bearing and from a tyre. Then the car goes on a lift and the driveshaft is checked at its joints and at the centre bearing with the shaft loaded by hand, and the axle oil is judged by colour and smell as well as level. A clunk taking up drive is looked for at the shaft couplers before the differential is blamed for it.

When several unconnected systems misbehave in the same week the thing they have in common is usually where their power comes from, and on these cars that is one module. It is still diagnosed as a circuit rather than assumed. We test for supply and ground at the load itself, measure voltage drop with the circuit under load rather than with a test lamp, and check what the module commands against what actually arrives at the pump, the motor or the lamp. A fuel pump relay circuit that switches on the bench and fails hot is exactly the kind of fault a quick check misses. Parasitic draw is measured overnight where a car is going flat. Only when the circuit has been proved do we talk about the module, because it is an expensive part to buy on a theory.

The housing on this engine sits in the valley between the banks and carries the oil cooler inside it, which means one plastic component holds pressurised oil next to coolant in the hottest part of the engine. When it distorts, oil runs down the back of the block and lands somewhere that blames a different gasket, and coolant can go the other way. We clean the area, run the engine and find where the oil is actually leaving rather than replacing the nearest seal to the stain, pressure-test the cooling system to see whether coolant is disappearing into the same part, and check the oil for coolant. It is worth being precise about this one, because from underneath it is easy to sell it as a rear main seal.

A heavy car braked hard on hot tarmac and then parked is the classic way to get uneven pad deposits on a disc, which feels exactly like a warped disc and is not the same thing. We check the disc for run-out with a dial gauge on the hub rather than deciding by feel, compare the temperature of the two sides after a road test, and free off and inspect the caliper slide pins, because a seized slide cooks one pad, leaves the other and produces both the judder and the smell. The wheel bolts and the hub face are checked for rust scale and correct torque, since an unevenly clamped disc gives the same complaint. New discs get bedded in properly or they will be back.

A wide car with a lot of weight over its front wheels and a driver who uses the throttle works these bushes hard, and here they harden and split from heat rather than corrode. The car goes on a lift with the wheels hanging and each joint is levered under load in turn — lower arm bushes front and rear, tie rod ends, the drop links and the rack mountings — until the knock belongs to one named component rather than to the front of the car. Vague steering is checked at the rack itself for play at the pinion and for a mounting that has gone soft, because a rack that moves on its mounts feels like worn joints and is neither. Geometry is reset after the work, since a new arm changes the angles that ate the tyre.