Why is my car so hard to start when cold?

So, you are running late. It is still half dark. The rain is pelting down; or the frost is thick on the ground with ice on the wind screen and you nearly slip over and drop your parcels. The wipers won’t clear the ice. Run back for warm (not hot) water and ……….. Turn the key ……… again and again …….. Still no fire!! Oh, nooo!

Some of the common reasons for the failure of internal combustion engines to start when cold:-

• Age – in vehicles of, say, 20+ years the rings will have weakened and the valves will no longer seat properly. Hence, poor compression. This is especially a problem for diesel engines. If your car is elderly it may be carburetted. In that case the shafts and bushes in the carby have worn, allowing too much air to enter the system. Equally the choke has lost tension or at least needs adjusting.
• Battery – Once upon a time we had a crank handle. Now we rely entirely on the battery. All the refinements and accessories on the modern car depend on a full voltage and unimpeded current flow. If the voltage drops below 10, the injectors will malfunction and the starter motor won’t turn and probably will not even push or roll start. Batteries usually have a guarantee for two years only. Of course, some last much longer but they need to be tested at least twice a year. The car may still be starting but the test will reveal any inner weakness, indicating the imminent demise of the battery – especially in the cold of winter. Get it tested!
• Carbon – builds up in the intake components, on the valves, in the breathers, especially in the environmental protection components and on the injectors. This accumulation not only diminishes performance and worsens fuel consumption but makes engines hard to start. A carbon cleaning process needs to be done every 2-3 years. This should include exhaust gas recirculation and crankcase ventilation components. Modern chemicals and applicators make this a relatively cheap procedure.
• Filters – blocked air or fuel filters starve the engine and place a heavier burden on the battery

Petrol and LPG engines depend on a good spark to ignite the fuel.  The Manufacturer’s hand book will say how often your car’s spark plugs should be replaced. If it doesn’t, then change them every 25,000 km. However, it probably will not talk about spark plug leads. Change them about every 80,000 km or sooner. Cold damp mornings can mean moisture lays around the distributor and leads, redirecting the current to earth rather than to the spark plug. An anti-moisture spray on the distributor and leads can help. Very modern cars no longer have leads. They have an individual coil mounted over each spark plug. This system is long-lived and failure will usually be confined to one coil only, allowing the engine to still start but run roughly. Additionally, a properly working coolant temperature sensor will inform the computer that it is a cold morning and it needs to release more fuel to facilitate firing.

Diesel engines rely on pre-heating the air in the cylinder so that the fuel will ignite more easily as it is atomised. Glow plugs are used for this purpose. With the key in the ‘on’ position a glow plug light will illuminate in the instrument panel for 10 seconds or so whilst the pre-heating is taking place. The ‘start’ position should only be engaged after the light extinguishes.

If you are experiencing hard to start issues, or she’s got ¼ million km up or its not been tuned in while, then you had better get into your favourite mechanic before it gets worse.

Like more help? ………… visit www.jackmans.com.au

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