Archive for December 2009
Castle Hill Mechanic checks coolant before a very hot summer.
December 8, 2009 | 
Author The cooling system in most cars consists of the radiator and water pump.
Water circulates through passages around the cylinders and then travels through the radiator to cool it off. In a few cars (most notably Volkswagen Beetles), as well as most motorcycles and lawn mowers, the engine is air-cooled instead (You can tell an air-cooled engine by the fins adorning the outside of each cylinder to help dissipate heat.).
Air-cooling makes the engine lighter but hotter, generally decreasing engine life and overall performance.
Although petrol engines have improved a lot, they are still not very efficient at turning chemical energy into mechanical power. Most of the energy in the petrol (perhaps 7 0%) is converted into heat, and it is the job of the cooling system to take care of that heat.
In fact, the cooling system on a car driving down the freeway dissipates enough heat to heat two average-sized houses! The primary job of the cooling system is to keep the engine from overheating by transferring this heat to the air, but the cooling system also has several other important jobs.
The engine in your car runs best at a fairly high temperature. When the engine is cold, components wear out faster, and the engine is less efficient and emits more pollution. So another important job of the cooling system is to allow the engine to heat up as quickly as possible, and then to keep the engine at a constant temperature.
Plumbing
The cooling system in your car has a lot of plumbing. We’ll start at the pump and work our way through the system.
The pump sends the fluid into the engine block, where it makes its way through passages in the engine around the cylinders. Then it returns through the cylinder head of the engine. The thermostat is located where the fluid leaves the engine. The plumbing around the thermostat sends the fluid back to the pump directly if the thermostat is closed. If it is open, the fluid goes through the radiator first and then back to the pump.
There is also a separate circuit for the heating system. This circuit takes fluid from the cylinder head and passes it through a heater core and then back to the pump.
With all these different parts it is important to get them checked periodically so before summer is really upon us be sure to call Zecks Mechanical repair at Castle Hill call 02 9680 1691 to get your cooling system checked.
Posted in Cooling system | 
Tags: Castle Hill Mechanic, castlehill mechanic cooling system | 
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Castle Hill mechanic does oil changes
If you imagine your car is like a human body, motor oil is the equivalent of blood. Your car needs oil to run, and the oil needs to provide the required lubrication properties specified by the engine manufacturer for you to have a happy and healthy car engine.
So what exactly does the oil do?
Oil lubricates your car’s engine and helps protect the moving parts, especially when you first start-up the engine. As you drive, water vapour, un-burnt petrol and gases from the engine’s combustion process all end up contaminating your oil. If you don’t change your oil at the recommended intervals, it can thicken, and lose its protective ability, as it can’t reach and protect the moving parts. When this happens your oil has lost its protective qualities and it’s time for an oil change.
What does the oil filter do?
The oil filter strains dirt and other particles out of the oil as it circulates. When changing oil, it’s best to replace the filter as well, as you don’t want a dirty filter contaminating new oil.
How often should I change my oil?
Most mechanics advocate oil changes should be carried out in accordance with the service schedule set by the vehicle manufacturer. Often this recommends an oil change every 10,000km or 6 months.
However, motorist’s should take care. Most manufacturers say that the frequency of an oil change is largely dependant on your driving habits. When you travel over 20km the oil in your engine has time to fully heat up, allowing it to flow freely and vaporise the water and unburned fuel that build up in the oil.
However if you rarely travel more than 20km after each cold start, your oil can become saturated with contaminants, failing to lubricate the engine properly and, over time, lose its protective abilities. This applies no matter what quality of oil you are using. If this sounds like you, most manufacturers recommend an oil change every 5,000km or every three months.
It’s also worth remembering that simply topping up an engine that’s low on oil is not the same as giving it an oil change. Contaminants left behind increase in concentration each time the oil levels drops which accelerates engine wear. In addition to this, the mixing of oil brands and viscosities can harm you engine, and is not recommended.
What kind of oil should I be using?
Today if you walk into an automotive shop you will be faced with many choices of oil, so which one do you need?
There are many brands of oil available, and different engines require oil of different levels of thickness or viscosity. Zecs mechanics will know best what to put into your car based on the manufacturer’s recommendation and your driving habits.
Most mechanics use a conventional motor oil that is a product of the crude oil refining process. This is the most basic oil grade recommended by most manufacturers to keep your car in good working order.
The next step up is a synthetic fortified oil like the Valvoline ProBlend that NRMA MotorServe uses. This is a synthetic blend that combines the properties of conventional and synthetic oil to help it burn cleaner and withstand greater temperatures, giving your engine greater protection than a conventional oil.
Synthetic oils are developed from chemical compounds such as polyalphaolefins. Their entire structure is different, and more stable than conventional motor oil. It is able to maintain viscosity, or flow, across a wider temperature range and under more severe demands. The best quality motor oil is therefore fully synthetic, although because it is costly to manufacture this comes with a significant price tag. It’s also not suitable for all cars.