16 how to identify fluid leaks from your car

how to identify fluid leaks from your car


By Adam Tudor-Lane on 2018-04-17 20:46:04

Over time every car ages, things just wear out...whether it’s a rubber hose, grommet, gaskets they all deteriorate over time. Spotting leaks isn’t always easy, a small drip on the drive often gets ignored until it becomes obvious, here’s a short list of the most common leaks and what causes them.

Power Steering Fluid

All cars these days are fitted with power steering, it makes driving easier...you don’t have to be Hulk Hogan to turn the wheel at low speeds any more. It’s now something we take for granted, until you realise you can barely turn the wheel, you need to summon the strength of the world’s strongest man to just get off your driveway. Some cars are more prone to power steering leaks than others, it’s worth giving your make and model a quick Google to see if it’s something you can prevent.

It’s caused by wear on either the feed or return lines, normally these are located at the very back of the engine bay near the bulkhead. Typically it’s the O-rings that deteriorate with age and weathering. They can break up and even get into the power steering system if you aren’t careful.

If your car is over 10 years old it’s a good idea to give these O-rings a check every now and then, maybe get them replaced at your next service to be on the safe side.

Power steering fluid tends to be a reddish pink colour, but it can also be clear.

Water Leak

Every car needs a radiator, they’re fundamental to the running of your car. Without one your engine would simply overheat and cook itself. Coolant fluid runs through the engine block, it then passes through small vein-like channels in the radiator. Air passes over these from both a fan and the air being sucked in from the front grille, this cools the fluid before it goes back into the engine block.

Radiator leaks are the most common form of leak, especially in old cars.

The cause comes down to corrosion. Being water based, coolant can produce sediment over time, this then collects in joints and channels in the radiator. Over time these start to rust, eventually the rust gets so bad it will eat its way through the metal, starting a leak.

You need to change your coolant every now and then to stop this from happening, it should ideally be replaced every 30,000 miles or so.

Also, make sure you don’t over fill your coolant. Doing so results in too much pressure in the system, as the coolant gets hot it expands, you need to leave room for this otherwise you’ll damage connectors and hoses.

Coolant fluid colour varies, it depends on the fluid your car needs and you shouldn’t ever mix different colours. Most are bright in colour, red, blue, purple etc.

Washer Fluid Leak

This is a tricky one to spot as it’s water based, washer fluid will tend to evaporate before you can notice it; especially in a hot engine bay. But there are more obvious signs of a washer fluid leak. Normally they happen around winter time when you haven’t used enough neat fluid in concentrated form. As the temperatures plummet water freezes, and when this happens inside the washer pump it normally cracks it, leading to a leak.

The same thing can happen in hoses and even washer jets. If you notice there’s no washer fluid coming out on a chilly morning then stop trying, you could blow the motor in the pump. Go and buy some neat screenwash to top up the reservoir, that should stop it freezing when the minus numbers hit.

Washer fluid comes in various hues, so just keep an eye out for the color you’re currently using.

Oil Leak

We left the biggest until last. Everyone will suffer an oil leak at some point in their life, it’s almost guaranteed.

Not only are they a massive pain but they also make a mess of your driveway, or end up costing you a fortune in top ups until you get the problem fixed. It’s best off taking your car to the garage as soon as you notice the first drop.

But what causes them? It’s normally seals around the sump or the oil filter, there’s a small washer that sits between the sump plug and another on the oil filter, often these aren’t changed when your car is serviced. Using the old, worn one nearly always ends up in a leak, when washers cost pence it’s pointless not replacing them.

You can also get oil leaks from old gaskets and corroded connectors or seals. With the majority of modern cars being turbo charged the oil lube feed is another common place for leaks, if you don’t get this fixed sharpish you’ll end up with a seized turbo and a rather large bill.

Oil will always be a dark brown or black colour depending on its age.

Transmission leak

A leaky transmission is harder to notice, it often takes a long time before any actual evidence occurs when driving. The tell-tale sign is to keep an eye out for dark spots on your driveway, these could well be minutia to start with, making them almost impossible to see.

Common leaking points are the transmission pan, it either becomes punctured or the pan itself works loose due to bolts that are improperly tightened. Fluid lines can also become damaged by heat or stones from the road, either puncturing or cracking the line over time.

There’s also a gasket around the pan which seals the fluid in. With age this begins to fray and crack, leading to them not aligning correctly. It’s an easy fix you can do at home, just remove the pan fit the new gasket and bolt back up.

Seals on the transmission can also degrade over time, they’re subjected to some really high temperatures which eventually take their toll. The leaks normally occur on either the input or output shaft.

The color of transmission fluid will vary on age, when it’s new it will be bright or dark red. But over time this will degrade to a black almost oil like consistency.

Brake Fluid Leak

This is probably the single most dangerous type of leak you can have. Brake fluid leaks can happen throughout the system. Steel hoses are coupled to rubber ones through various valves, cylinders and pistons. It’s one of the most intricate mechanical setups in a car.

Seals and O-ring can again degrade over time, especially in the master and slave cylinder where the pressure is at its highest. It can also happen in the calliper, either at the bleed screw if it becomes corroded or inside the calliper itself where the pressure plate presses on the pad. It’s surrounded by a rubber seal which becomes weak with age.

Thankfully pretty much all modern cars have warning lights to tell you if your braking system isn’t working as it should. If the light flashes up on your dash get it seen to by a garage straight away.

Brake fluid has a slightly yellow tinge to it, almost like beer or shandy. Over time it becomes dirty and turns black.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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