Driver Mis-Fuelling Can Cost Up To £3,000 A Time To Repair Says Lex
Published: 29th May 2005
Common rail diesels are most costly to fix
Drivers who mis-fuel their diesel cars with petrol can expect a costly bill to repair the damage, according to Lex Vehicle Leasing.
The Lex maintenance department, which spends around £50m a year on the upkeep of its 123,000 vehicle fleet, is seeing repair costs range from £300-£3,000 depending on the type of diesel engine fitted to the car.
Most at risk are the modern common rail diesels which are built to more exacting tolerances than standard diesel engines. If petrol fuel gets into the common rail diesel system it can mean replacing both low and high pressure fuel pumps, injectors, rail, line filters and tanks, which can easily cost a few thousands pounds to fix.
"The cost of the repair depends on whether the driver has simply started the engine or they have driven it for a few miles with the wrong fuel in the system. The longer the petrol has been in the system, the more money it will cost to repair," said Jamie Wiseman, Lex Vehicle Leasing’s maintenance manager.
"Manufacturers are now giving their dealers detailed advice as to which stage the mis-fuel has reached and the correcting action they must take. We had two Mercedes common rail diesels to repair recently which cost £3,000 per engine," he added.
All costs to repair mis-fuels have to be met by the consumer as manufacturer breakdown cover does not cover mis-fuels, although they are likely to come out to your car and take it to the nearest dealership. Also if a car is on a PCP or contract hire agreement it will still be up to the driver to pay for the damage, rather than the finance company.
Lex is advising drivers to adopt the same principles as rental companies where the car’s fuel access flap is labelled with the relevant fuel type, or a relatively discreet label is put inside the car.
"When repairs are costing up to £3,000 it’s worth drivers taking some precautions to prevent them from mis-fuelling. Rental companies have seen mis-fuels come down significantly by taking these precautions so it’s worth the investment in clear labelling for the driver," said Wiseman.
Technical reasons why mis-fuels cause such misery
Diesel oil is a lubricant, while petrol is a solvent. Diesel fuel injection equipment needs to be lubricated by the diesel oil when the engine is running. Not all the fuel delivered to the fuel injection system is used, in fact around 70% of fuel is returned to the fuel tank. As petrol is a solvent it strips the lubricant off the engine’s working parts so causing metal to come into contact with other metal parts which can generate debris inside the engine.
Any debris from the injection system can be returned to the tank and then drawn back up and passed through the system again which will cause problems.
After filling a diesel engine vehicle with petrol a common misconception is that just putting the ignition on will be OK and that no damage will occur to the system. Most systems now use a low pressure electric pump fitted in the tank or sender unit, contaminated fuel is immediately circulated through the pump and fuel rail, once the ignition is turned on. Where the vehicle has a mechanical gear driven pump the same level of contamination will occur if the engine is run.
It is imperative the fuel tank is drained of fuel completely, preferably off the vehicle. DO NOT use the electric pump, the pump is lubricated by a diesel. Running with petrol causes the internal bushes to fail which transfers metal swarf to the rest of the fuel system. As most tanks have baffles in them, the tank must be partially filled with clean fuel and swilled repeatedly until there is no further evidence of debris in the expelled solution.
The fuel lines (feed and return) must be blown through to evacuate any residual fuel. Fresh fuel should be purged through the lines with the injectors disconnected.
Common rail vehicles will not tolerate any petrol, in fact the manufacturers of the fuel injection system state that any petrol contamination should necessitate replacing the low pressure pump, high pressure pump, injectors, rail, lines filters and tanks. This is not really practical and usually costs more than a fully dressed engine. A certain amount of common sense should be used, but after such an event the customer should be warned any consequential damage within a certain time will necessitate a contribution.
