Mechanic in Earlville

Stop-start is the hardest thing you can ask of an automatic

Earlville sits on Mulgrave Road, which carries most of the traffic between the southern suburbs and the city, and a lot of Earlville driving is exactly the kind that cars find hardest.

An automatic transmission generates heat through its torque converter, and it sheds that heat into the air. Sitting in slow traffic is the worst combination available: the transmission is working, and there is almost no airflow to carry the heat away. Do that in ambient temperatures in the thirties and the fluid is running near the top of its range routinely.

Heat is what degrades transmission fluid, and degraded fluid protects less and cools less, which makes more heat. That loop is behind most automatic failures, and it is why we treat fluid condition as a genuine diagnostic rather than a line on an invoice. Some manufacturers describe their fluid as filled for life, and in this climate on this kind of driving that claim deserves a conversation. It is covered on the clutch and transmission page.

Air conditioning in traffic

The other complaint we hear most from around here has a very recognisable pattern: the air conditioning is cold on the highway and stops being cold in traffic.

That pattern almost always means the condenser is not shedding heat. At speed there is enough airflow through it to work anyway. In queued traffic there is not, and whatever is wrong shows itself. Usually it is a condenser blocked with road grime, insects and salt, or a cooling fan that is not running when it should be, which is an electrical fault rather than an air conditioning one.

The cheapest possible cause, and a very common one, is a cabin filter that has completely choked. In this climate they load up fast, and a blocked one reduces airflow so much that the whole system gets blamed. It is worth eliminating before anyone quotes you a regas.

Worth knowing generally: an air conditioning system is sealed, and it does not consume refrigerant the way an engine consumes oil. If the gas is low, it went somewhere. Paying for a regas without finding the leak is paying to fill a system that will empty again.

Long-owned cars

Earlville has a lot of established housing and, with it, a lot of cars that have been in the same hands for a long time and have low kilometres for their age.

Those cars need a different conversation. Almost every service interval is expressed as kilometres or years, whichever comes first, and it is the years half that gets ignored. Rubber and fluids age on their own, and heat accelerates it, so a nine year old car with 60,000 kilometres on it is well past several intervals even though the odometer says otherwise.

The one where that really matters is the timing belt. On an interference engine a snapped belt destroys the engine, there is no way to inspect a belt for remaining life, and a low-kilometre car is exactly where an overdue one hides. If nobody knows when it was last changed, assume it has not been.