Tag Archive | "decoking"

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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bG9nZ2VyX0xvZ28uanBnIjtpOjI7czo3MzoiaHR0cDovL21vdG9yYmxvZ2dlci5jby51ay93cC1jb250ZW50L3dvb191cGxvYWRzLzMtTW90b3JfQmxvZ2dlcl9Mb2dvLnBuZyI7fTwvbGk+PGxpPjxzdHJvbmc+d29vX3ZpZGVvX2NhdGVnb3J5PC9zdHJvbmc+IC0gQXV0byBOZXdzPC9saT48L3VsPg==