Turbo Failure: Symptoms and What Causes It

How a turbo works

A turbocharger uses the flow of exhaust gas to spin a turbine. That turbine drives a compressor on the same shaft, which pushes extra air into the engine. More air means the engine can burn more fuel and make more power, which is how a small engine can feel much bigger.

The shaft spins extremely fast and gets very hot, and it runs on a thin film of engine oil. Almost every diesel car on the road has a turbo, and so do many modern petrol cars.

A healthy turbo makes a gentle whoosh or faint whistle as it spools up, and that is normal. It is changes in the sound, or noises that come with a drop in power or smoke, that are worth paying attention to.

Signs your turbo is struggling

The first thing most people notice is a loss of power, especially when accelerating or going up a hill. The car may go into limp mode, and the engine management light may come on.

Other signs include a loud whistle or a siren-like whine that is new or getting louder, blue or grey smoke from the exhaust, heavy black smoke from a diesel, and the car using more oil than normal. If you find oil inside the intake pipes, that can also point to the turbo seals.

It is not always the turbo

Many of these symptoms can come from something around the turbo rather than the turbo itself. A split boost hose or loose clamp, a sticking actuator, a faulty boost sensor, a blocked DPF or a sticking EGR valve can all cause a loss of power or limp mode.

Those faults are often much simpler to fix. That is why we diagnose properly before replacing a turbo. We read the fault codes, check live boost data, look for leaks and inspect the turbo for shaft play and oil.

What makes turbos fail

Most turbo failures come down to oil. If the oil is low, old, the wrong grade or contaminated, the bearings that carry the shaft wear quickly. A blocked oil feed pipe can starve the turbo completely.

Other causes include something being sucked into the turbo, such as debris from a damaged air filter, and running the engine hard then switching it straight off, which leaves the hot turbo without oil flow. When we fit a new turbo we look for the root cause, such as a blocked oil feed, so the new one does not go the same way. We always give you a quote before any work starts.

How to make your turbo last

Keep up with oil changes and use the oil grade your manufacturer specifies. Check the oil level regularly between services, as a turbo engine can use a little.

Change the air filter when it is due, and make sure it is sealed properly in its housing, so nothing gets past it into the turbo.

Let the engine warm up before you drive hard, and after a long motorway run or towing, let it idle for a short while before switching off so the turbo can cool. Get any boost or power problem looked at early, before a small fault puts strain on the turbo.

Get it checked in Pelsall

If your car has lost power or started whistling, we can find out why. We look after drivers from Pelsall, Bloxwich, Aldridge and across Walsall. Call us on 01922 682200 or book online.