Tag Archive | "engines"

To De-coke Or Not De-coke?

A generation or so ago it was a relatively common sight to see car owners beavering away in their garages and on their driveways, routinely servicing their cars. The more experienced would go a stage further, whip off the top-mounted equipment and the cylinder head and de-coke the engine. Forty or fifty years ago this was standard practice every ten thousand miles or so.

Over extended periods of time whilst engines are working there is a tendency for deposits to accumulate where there is combustion. This carbon build-up very gradually affects performance, economy and a loss of cylinder compression, usually around the piston rings. That’s the short version.

The need for regular de-coking was an inevitable result of short journeys and, in particular, dirty fuel. The quality and built-in cleaning properties of the best modern fuels has to a great extent limited this problem until at least a car gets fairly aged. However, these days it is still perfectly possible for an engine to accumulate carbon deposits in the same way that a kettle will in time fur up and perpetual short trips are likely to be the culprit along with using cheap, unbranded petrol.

The other problem today that many drivers will encounter is their own helplessness. We have lost the knack of fixing things ourselves. Your grandfathers could probably take plumbing, routine car maintenance and electrical wiring in their stride. These days many people don’t know how to fix a 13 amp plug to an appliance. It’s this lack of expertise that has resulted in some garages getting away with £100 per hour labour charges.

Opening the bonnet of a modern car can be a bit daunting to a novice; but underneath all the fancy do-dad’s there is still just a basic internal combustion engine. Obviously Granddad had a much easier time removing a carburettor than the modern motorist would with complex fuel injection, but the art of home mechanics is still feasible; but it does still require the removal of the cylinder head so, although it is a straightforward job, it is not for the faint-hearted!

Thankfully, it is unlikely that your car will ever need this drastic intervention. If it does, your engine will tell you. The car is likely to suffer from pre-ignition (aka ‘pinking’ or ‘knocking’) and performance will be generally weaker and emissions worse. The bad news is that it is such a gradual process that the average driver won’t notice.

There are solutions in a can that can be sprayed into air-intakes and are supposed to clean out the inner working parts like a laxative. Some people rate them; others don’t. To avoid coking the sensible driver will fill up with good branded fuels and ensure the car gets a decently long weekly run-out that makes the engine work harder – especially if the vehicle is mostly used as a local runabout. Selecting high gears at low revs may be good for economy but engines are built to perform. Exercise is as good for cars as it is for us.

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Oil And Water Don’t Mix – Check Your Engine! Part Two.

Down in the bowels of your engine where wise men fear to go lies – the gearbox. Otherwise known as the transmission, this is an area of the car that tends to be overlooked but it too sometimes needs attention. Auto ‘boxes need a little more TLC than their manual counterparts. The gear oil needed is usually red, which helps to differentiate it from engine oil and helps identify tell-tale signs of problems. Fortunately, gearbox lubricant doesn’t need changing with anything like the frequency of engine oil.

As with the engine oil in Part One, if you feel metal flakes in the fluid on your latex gloved fingers then your gearbox is eating itself and repairs are needed. When clutches are slipping a burning smell occurs and a remedy is called for. Change that clutch fast! As mentioned, transmission fluid is usually red but if it turns to a schoolgirl pink then, somehow, coolant is mixing with it. The bad news here is that coolant has a tendency to attack the seals in the transmission so you have to find the leak, change the seals and replace your gear oil immediately. Again, like engine oil, if the fluid is foamy or sticky then it is an indication that your gearbox has overheated at some point or has been over filled. Put simply, when there is bubbles in oil there must be air and air doesn’t lubricate.

You know that sinking feeling when you notice a puddle under your car? Yes, that’s right – there’s a leak. If the offending liquid is brown or black then it is engine oil. Get some on your finger and sniff it. If it smells like oil then it is oil. If however, the leak is red then it’s coming from the transmission. Seriously, don’t put your finger in this one. If it appears to come from the centre of the car then it is the gearbox, if it’s near the wheels then it is probably brake fluid. Either way, go directly to your garage.

Next, there’s that good old standby, the water leak. If the liquid is clear then it is probably just run off from scuttles or drainage points. You also get it as part of the normal operation of air-conditioning systems, so nothing to worry about. If it is green or blue then it’s coolant. The location of the leak will give clues as to where it is coming from. The water pump, the radiator or a hose. Often these are simple jobs that can be done at home. Just don’t delay.

Finally, a word about dead rainbows. These appear under your car when any form of oil leaks into water. The two don’t mix so form rainbow colours when light is reflected off them. Have your car checked for leaks anywhere. Any form of leak affects the performance of your car in some way and, if not attended to, could herald serious and expensive problems in the near future. Repairing or replacing gearboxes is horrendously expensive. Regular maintenance is key to a happy life with your beloved motor.

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