The Colour of Exhaust Smoke Explained
It’s rare that you’ll see smoke coming out of your exhaust system, which is precisely why you should take notice when you do. Modern cars are designed to pump spent gasses quietly and efficiently; so, if you see grey, blue, white, or black smoke emissions it’s probably a sign that something’s amiss. In this blog, the Country Vehicles team explains what to do if your car exhaust is smoking, according to the colour of the smoke.
Identify the Smoke is Coming From Your Exhaust
The smoke most people see coming from their exhaust isn’t actually smoke, it’s steam. When you start a cold engine, it creates water vapour as it starts to warm up. This causes condensation in the exhaust, which appears from the exhaust pipe as steam which looks like wispy smoke. This should stop after a few minutes of driving.
More unusual is smoke that’s emitted when the car is stationary, or as it accelerates. If you become aware of a smoky exhaust, check when it happens, and what colour the smoke is. There are 4 colours to look out for – black, grey, white, or blue – and you should also note whether the smoke has a particular smell.
Now we’ll take a look at each of the colours, to determine what to do if your car exhaust is smoking.
1. White Smoke From Your Exhaust
If this is happening a little while after you start the engine, what you’re seeing is steam rather than smoke. In which case there isn’t a problem. If, however, the white smoke persists throughout your journey, and appears to be quite thick, there is probably an issue, and you need to take your car to a local garage for an exhaust check.
Thick and consistent white smoke can by a symptom of coolant leaking into your engine, which suggests that a head gasket may have failed. This can’t be ignored as it will get worse with time and could even lead to engine failure.
2. White Smoke Tinged With Blue
You sometimes see this kind smoke after your car’s been through a service. It’s a symptom of oil burning off and so long as it stops after a bit, there’s no reason to be concerned. If, however, you’re driving an older car, that hasn’t been serviced recently, it could be that worn piston rings or valve seals are allowing oil to leak into the fuel system.
If the latter is the case, you’ll need to let an experienced car technician take a look. It’s a fiddly job to replace the seals, but it will stop the oil loss and solve the issue.
3. Grey Smoke Emissions
There are two things that could be causing grey smoke from your exhaust. In our experience, it’s either a faulty PCV valve, or – if you have an automatic vehicle – it’s a transmission fluid leak into the engine. A PCV valve is pretty simple to deal with, whilst the leak is a more serious issue. In either case, your car needs professional attention promptly.
4. Black Smoke From Your Exhaust
If your car uses petrol, black smoke is a sign the excessive fuel is being burnt. To remedy this, you should check the air filter, and replace it if necessary. If the air filter isn’t the problem, you’ll need to ask a mechanic to check the fuel pressure regulator and the fuel injectors.
Black smoke in diesel cars is more common; it’s likely to be caused by a build-up of soot from unburnt fuel. Soot deposits can develop over time, especially if the car is normally driven at low speeds, This can be dislodged by taking the vehicle onto a motorway and driving at 70mph to clear the system. You should see a ball of black smoke emerge.
Exhaust Repair and Replacement in Shefford
Country Vehicles in South Bedfordshire offers a complete exhaust repair and replacement service for all major vehicle makes and models. We’re a highly skilled team offering a range of services from our independent garage. Apart from exhaust checks, we also replace tyres, offer brake checks, and provide regular servicing to keep your vehicle in tip-top condition.
Need some professional attention for your smoking exhaust? Give Country Vehicles in Shefford a call and we’ll be happy to take a look straight away 01234 381555