DPFs – THE BACKGROUND OF ON-CAR TREATMENTS

On-car cleaning chemicals can save the often considerable hassle of removing a DPF but it can be difficult to select the appropriate product. This situation leads Rob Marshall to ask trusted specialists about how their solutions can help you

Taking the easier option is not always the worst one. Within the realms of DPF cleaning, you are not taking a risk by relying on a bottle of potion – provided that it is used correctly. Trusting in businesses that have invested in their products, with proven track records, provides extra reassurance. For this reason, we have consulted BG Products, JLM Lubricants (via its UK distributor, Kalimex) and Liqui Moly for advice on their offerings.

Prevention is key

All companies agree that the best strategy starts early. BG Products is emphatic that limiting soot production makes the DPF last longer, in addition to further benefits. As an active regeneration consumes close to 25% more fuel, and reduces the lubricating oil's life, it is worth promoting these long-term savings to a customer at service time. Liqui Moly concurs that, if aged oil is left within the crankcase, deposits can form on the piston rings, making them stick, reducing compression. This creates excessive oil consumption, which not just increases DPF clogging rates but the metallic elements within the oil also reduce DPF life. Liqui Moly stresses the importance of garages using the appropriate low SAPS oil, because oil ash cannot be removed by on-car DPF cleaning methods.

Reducing oil consumption extends DPF life. BG Products advises that its EPR oil flush is the most cost-effective way of protecting a DPF. Its formulation focusses on cleaning deposits from piston rings, keeping them flexible and preserving their sealing quality.

BG Products adds that injector cleanliness is vital for optimum fuel atomisation. Interestingly, it finds that high-pressure common rail injectors are not just prone to deposits but also dedicated chemistry is required to clean them adequately. Therefore, when carbon afflicts dirty injectors and low-tension piston rings, the DPF is exposed to double trouble. Firstly, incomplete fuel atomisation overloads it with soot deposits. The reduction in compression from stuck piston rings not just exacerbates the situation but also the increase in blow-by gases means that oil vapour is drawn into the intake system, thus increasing ash loadings.

Liqui Moly says that its Diesel System Cleaner additive cleans and frees fuel injector nozzles. It also removes troublesome deposits from both the fuel system and combustion chambers. The result is restored fuel atomisation and reduced DPF soot loadings.

Liqui Moly advises that its Diesel System and Diesel Particulate Filter fuel additives are dosed every second service. They are geared more towards preventative filter cleaning, especially on cars that are driven infrequently.

JLM Lubricants markets several preventative maintenance products. Its DPF ReGen Plus fuel additive enhances the regeneration process, by allowing the soot to burn at reduced temperatures. Dependent on driving habits, one can should be dosed into the tank once every 2,000 – 3,000 miles, or every three months, whichever the sooner.

JLM Lubricant's Diesel Extreme Clean includes not just the DPF but also the injectors, EGR valve(s) and turbocharger vanes. It should be viewed as an all-in-one cleaning package that dissolves minor blockages, fixes irregular running and improves fuel consumption.

Should replacement be the only option...

LKQ Euro Car Parts reminds garages that Euro V cars onwards must be fitted with a type-approved replacement DPF.

Effecting a cure

Fuel additives can work against you, should you need to cure a DPF blockage. Therefore, query the car owner if any DPF-related additives have been dosed into the tank already. The danger for you is that the DPF might overheat and you could be liable for any resultant melted monoliths. For the same reason, do not dose additives when you suspect a soot-related blockage.

Even so, on-car DPF cleaning is possible, using a range of chemical options that have been designed for professional workshops.

BG Product's 9300 intake and dpf cleaning system initiates and controls the DPF regeneration process. Cleansing chemicals are introduced through the air intake to disperse hydrocarbons from the inlet to the DPF. BG Products advises technicians to watch the exhaust gas temperatures throughout the procedure and to adjust engine speed and airflow (using a supplied adjustable venturi) to keep them within the prescribed range. It is advisable to dose EPR oil flush into the sump afterwards and to finish the task with an oil change to help restore any lost compression via dirty piston rings.

Liqui Moly's cleaning kit comprises a DPF Gun, a DPF Probe with interchangeable tips and a selection of chemicals: the Pro-line Diesel Particulate Filter Cleaner & Pro-Line Diesel Particulate Filter Purge. These are injected into the DPF directly. The DPF cleaner dissolves surface-hardened, dense and encrusted contaminants. The DPF purge flushes the soot softened by the cleaner and distributes it within the DPF, so that it can be burned off during subsequent regeneration.

Further details of the process can be viewed online here

JLM Lubricant's cleaning toolkit works similarly to that of Liqui Moly's cleaning kit, by injecting a suitable chemical to loosen the deposits and then using another one to distribute the deposits around the DPF for burning during regeneration.

An interesting variation from JLM Lubricants is the DPF spray, which is an aerosol can that contains chemicals that dissolves the deposits. It is also injected into the DPF directly and reduces the soot's combustion temperature, so it burns off quicker and at reduced temperatures.