How To Diagnose A Leaking Car Engine

Car engines are just the same as other mechanical devices in a lot of ways. If they are well-maintained, they will offer years of reliable service, but if they are ill-maintained, you can expect to spend a lot of money on a regular basis in order to keep them going!

The majority of engines in cars are powered by petrol or diesel fuel, and also require other fluids to lubricate or cool certain components. If you start to see some odd-looking fluids appearing on your driveway, and you think that they are coming from your car, this handy guide will show you how to locate the source and identify them.


Photo via Flickr

Identifying the source

The thing about fluid stains is that you can’t always be sure whereabouts they come from on your car’s engine, or if indeed they originate from your car at all! If you share a driveway with other family members or occupants in your home, there is the possibility that those oily patches might originate from one of their cars.

Before you panic over an impending (and expensive) car repair bill from your friendly mechanic, the first step you need to take is to identify the source of the leaks.

There are two ways of doing this:

  1. You can park your car on an otherwise clean part of your driveway overnight, and then take a look underneath your car’s engine the next morning to identify where the leaks are coming from (or even if they are coming from your car at all);
  2. You can put some clear cardboard underneath your car after driving it for a while, and seeing where any fluid drips from.

If you have determined that the leaks are indeed coming from your car and not anyone else’s, the next step is to see whereabouts on your engine they are dripping from:

  • Oil leaks will usually occur where the sump plug is, or they may be dripping down higher up the engine;
  • Coolant leaks will typically appear from the front of the engine (where the radiator is), or from any connecting pipes;
  • Power steering fluid leaks are only visible when the engine is on and you are turning the steering wheel, although they could also appear from connecting pipes;
  • Brake fluid leaks can occur from any of the car’s four wheels, or the master cylinder, brake servo or ABS unit located in the engine bay;
  • Windscreen washer fluid will normally leak from the bottle or an area near there (such as the pipes going to your bonnet’s washer jets).

Not sure what you are dealing with?

Sometimes it can be hard to work out what fluid is leaking from your car’s engine. According to Mark from Big Motoring World Canterbury, power steering fluid is also used to lubricate automatic transmissions!


Generally speaking, you can usually identify what the fluid is by its colour and consistency.


Oil is typically black or dark brown, power steering fluid is red or red/brown, brake fluid is pure black, coolant is either red, green or blue (and has a sweet smell to it), and windscreen washer fluid is usually light blue in appearance.

Full time and dedicated blogger who loves to read and write everything about newest cars, exploring and hence, love to ride old classic cars!

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