Ask the Mechanic: Why does my car fail to start?

My Mazda Millenia could not start so I jump started it. When it finally started, it made a loud clicking noise while driving and when the engine was idle. The next day, the car started with no clicking noise, but the next time I tried to start it that day, it would not start. Again I tried to jump it, but it would not start. When turning the key in the ignition while trying to jump the car, there was a clicking noise. Do you think this is a starter problem or could it be a broken timing belt?

Betty.

Hello Betty, you may be getting mixed signals and confusing your Mazda’s symptoms. Have your battery and charging system inspected. If they are fine, have the starter motor inspected to ensure the starter brushes are not worn out or obstructed by accumulated soot. Also, inspect the starter solenoid (which converts electrical energy into a mechanical work to help rotate the starter motor which turns or cranks the engine) Let us try to isolate the symptoms and possible causes.

Often, you need to jump start your car if your battery is flat or has dropped charge way below 12 volts. This is usually caused by a bad battery, loose battery terminals, prolonged parking or a damaged alternator (charging system) but rarely battery drain by faulty electrical components or circuits. A bad starter motor will make a clicking sound as you turn the ignition key without turning the engine. Many times, motorists try to jump start the car unsuccessfully, thinking that the battery is faulty.

The starter motor brushes may be dirty or worn out which prevents contact with the field coils of the armature. A gentle tap can dislodge some dirt and allow it to start for only a couple of times. In the event that the solenoid is faulty, you will not be able to nudge the starter to turn your engine. A good car electrician or technician can inspect and replace or service the starter motor.

A broken timing belt does not make a clicking sound. However, a worn out timing chain will have a loud rattle as you start or run the engine. Either way, a broken or worn out timing belt chain can cause severe damage to your engine and prevent engine start. However, it does not prevent cranking or starter motor turning of the engine. In fact, whenever you crank the engine and it does not fire up, do not persist as you may be causing more damage to valves and pistons if the timing belt has snapped.

A mechanic will confirm if the timing belt has snapped by manually turning the engine. A persistent clicking noise as the engine runs could be caused by worn out engine-belt (not the timing belt) pulleys.

The V-belt pulls accessories outside the engine such as the alternator, steering pump, cooling fan or air conditioning pump. The pulleys will fail overtime and should be inspected before they damage the V-belt and stop accessories from running.

MY CAR STILL MAKES NOISES EVEN AFTER SUSPENSION AND STEERING SYSTEM REPAIRS

Hello Paul, of late, the front under tyre of my Toyota Vanguard makes noise when driving. After changing the shocks, steering rack and suspension bushes, the car is stable but when I drive on uneven speed humps at just 20km, there is a noise as if the metals are rubbing against each other. What could be the issue?

Moses

Hello Moses, the front shocks, steering rack and suspension bushes replacement is a major repair activity. A mechanic usually identifies and red flags worn out bushes, leaking shock absorbers or clanking and leaky steering racks during inspection.

It is sometimes a process of elimination based on what is evidently worn out or damaged. If you have persistent knocking or clanking (metal to metal) noise, then you need to ask the mechanic to test drive the car, listen to the noise and review the fixes as well as widen the inspection scope. An experienced mechanic should be able to reasonably discern what type of noise is audible.

A quick look over will confirm that all replaced components such as the steering rack, tie rod ends or shock absorber and control arm bushes are tightly fixed and none have failed.

There are other components such as the upper control arms, lower ball joints and stabiliser link bars that can be inspected to confirm they are not damaged and causing this persistent noise.

The steering and front suspension systems have several components which work together to ensure that you are able control the direction the car goes, manoeuvre safely around corners and sharp bends while the car recovers from road forces, remains stable and smooth as you drive.

These systems work so hard and depending on which terrain you drive or your driving style, they are bound to need overhaul as they will fail sooner or later.

WHY ARE MY BRAKES SOFT?

My 1992 Toyota Camry blew a leak on the left front brake hose, passed the midway clamp. The pads had been replaced 10 days before. Other than the visual brake fluid near the wheel there was no noticeable brake pressure loss while driving. Challenge is, there is a lot of brake pressure while driving but as soon as you start it and depress the brake pedal it drops to the floor with little or no pressure. What can we do?

Moses

Hello Moses, your Toyota seems to have a brake fluid pressure loss caused by the leaking front brake hose you have mentioned. That is why your brake pedal sinks low when you step on it before you start and run the engine. A car brake system relies on the brake master cylinder and brake fluid to pressurise brake lines. This delivers brake fluid which in turn provides hydraulic pressure to stop the car by engaging the brake pads to the discs.

A leak of brake fluid will reduce the hydraulic pressure, make the brake pedal spongy and increase braking distance or delay stopping the car when you need to. It is easy to misdiagnose this symptom as having a bad brake master cylinder. What you must do is urgently replace the leaking brake fluid pipe with another one. Avoid the temptation to weld or repair the leaking point if there is the option to replace the leaking pipe with a good one (used or new).

Welding brake pipes should be last resort because it has some failure risk. Renew all the brake fluid as aged brake fluid causes overheating and corrosion damage which damage brake hoses and cylinder seals. Aged brake fluid tends to have moisture which reduces its hydraulic effect and causes corrosion damage.

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