Text: Stephen Smith
As diesel engines become more powerful and economical, they also get more sophisticated. Common-rail injection technology means that the fuelling systems are operating under huge pressure, and many new-generation diesel vehicles can only run on high quality 50ppm diesel (see panel on international diesel quality).
So what happens when dirty fuel gets in there?
Vehicle manufacturers install sensors that detect water in the diesel, to prevent engine damage. And vehicle manufacturers obviously can’t be held responsible for dirty fuel being put into that vehicle and therefore damaging it.
Take our case as an example.
While we were on a trip from Johannesburg to KwaZulu-Natal, in rainy and very wet conditions, we filled up with diesel fuel, near Harrismith. A few kilometres later a light that we had never seen before came on. This was 16km after we had left the service station.
We stopped as soon as we could safely do so, and hauled out the vehicle’s manual, to find out what the warning light was all about. It wasn’t good news: the light indicated water in the diesel.
We phoned the General Motors Roadside Assistance hotline, which in turn contacted a mechanic and got him to phone us. The mechanic told us that the light was probably not a problem. Certain diesel fuels, he said, are lighter in consistency than others and the sensors battle to tell the difference between these light fuels and water.
He wanted to know if the engine was running smoothly when the light came on.
We said it most certainly was.
Carry on driving then, he said.
So we did.
For another 500km we drove our vehicle with that warning light showing, but at no stage did the vehicle shudder, run rough or show any signs of being unhappy. In fact, fuel consumption dropped a little to 8,5 l/100km.
Then, on our way back Gauteng, we filled up with a different brand of diesel.
Less than 20km later the Captiva’s turbodiesel engine lost power, seemingly reverting to “limp mode”. We again phoned the GM hotline.
They organised a rental car for us and a tow for the Chevy to a GM dealership in Pietermaritzburg.
The result? The fuel was tested and found to be contaminated with water. The tank was drained, filters were replaced and the vehicle test-driven.
But that warning light refused to be dimmed.
So eventually the fuel pump and injectors were replaced, and the vehicle was once again operating perfectly.
But what was the problem? Where did the dirty fuel come from? Who is responsible for the (hefty) repair bill of almost R30 000?
Because the problem was caused by dirty fuel, and not a vehicle fault, the repairs would not normally be covered by the warranty.
But we had followed the advice of a GM mechanic, so were we out of the woods, as the “owner” of the vehicle?
Was it the mechanic’s responsibility, or that of the GM Roadside Assistance division?
The repair bill was settled, presumably by GMSA, since the vehicle is the company’s property. But what would have happened if this had been Joe Public, driving his own vehicle? Would Joe Public be expected to cough up R30 000, and spend about a month without a vehicle, while repairs were being done?
Or would the fuel station be responsible for the costs, considering it supplied contaminated diesel? But which fuel station, because we used two? And how on earth does one prove that the diesel came from a particular fuel station? What would our chances be of getting the fuel station to pay?
To get answers we approached General Motors, TJ (Leisure Wheels fuel expert) and BP (who did NOT supply any of the dirty diesel).
Here is what they had to say: