When it comes to engines and particulate filters, garages need to emphasise to customers that cleanliness really is next to godliness, as Rob Marshall investigates
The irony of engines becoming dirtier internally to become cleaner externally is not lost on AT. The demand for lower tailpipe emissions has resulted in not just greater quantities of contaminations but also components being more vulnerable to these impurities.
According to the 2019 World Fuel Charter,
“The conformity of modern engines with their specified performance in terms of power, fuel consumption and emissions over time will depend largely on the cleanliness of their injectors”.
However, while pump fuel contains cleaning additives, the quantity and specifications vary between brands, despite the base fuel being, broadly, the same. In many cases, therefore, forecourt-purchased petrol and diesel cannot be relied upon alone to keep the injectors clean, let alone other parts of the engine.
Dirty injectors cause incomplete combustion. In the case of diesels, the resultant additional soot particulates are captured by the DPF, encouraging increased active regeneration cycles. This situation not only raises fuel consumption even further but also emissions. Petrol engines do not get off lightly either, with suboptimal fuel injector performance raising emissions, reducing oil life and promoting contamination build within the crankcase and air inlet tracts.
Highlighting additives upsells
Many garages upsell quality oil and fuel additives as preventative measures to break the vicious circle that accelerates deposit accumulations. BG Products informs AT that, if deposits on an injector cause suboptimal combustion, more deposits are formed, which sap power and increase exhaust emissions further. The company highlights that its BG44K or BG245 fuel system cleaners are, therefore, formulated to remove the hard-baked deposits within the injector and on its tip.
Using a decent oil flush, prior to draining, is also a prudent upsell. Aside from suspending as much contamination as possible within the old oil just before the sump plug is removed, BG Products reports that its EPR flush helps to reseal low-tension piston rings that are becoming especially popular with GDI engines. If left unchecked, the resultant compression loss contaminates the oil prematurely with fuel, causing oxidisation, thickening and, ultimately, sludge and varnish deposits.
Clearly, this latter issue degrades the oil’s additive packs prematurely, resulting in reduced engine protection. As compression is likely to leak past low-tension rings between now and the next service, an extra oil additive package may be useful to support the existing lubricant. BG Products says that such conditioners help to control soot loads, maintain viscosity for longer and suppress acid formation.
The company offers reassurance that its additives do not work against the chemistry within the engine oil. As ash deposits within a particulate filter are accelerated significantly by oil consumption, BG Products reasons that any means of cutting oil consumption will reduce DPF ash loadings. Therefore, keeping injectors and the crankcase clean benefits not just fuel consumption and emissions but also enhances DPF reliability.
On-board fuel additives (diesels)
While on the topic of additives, on-board Fuel Borne Catalysts were pioneered by PSA (now Stellantis), which licensed the technology across a variety of brands, from Mazda to Volvo. The fluid, ‘Eolys’ being the OEM reference, is contained in either a separate tank, or pouch, which possesses a dedicated pump and injection system to dose the diesel tank after every filling station visit. The additive reduces both the time and temperatures needed for DPF regeneration. Invariably, the additive does not last forever and either the pouch should be replaced, or the additive tank replenished, at set intervals.
An impecunious car owner may be unprepared to pay not just for the replacement fluid but also for the labour and necessary diagnostic intervention. However, a garage should resist either disabling the system, or tricking it, by simply resetting the counters, or filling the Eolys tank with diesel. Apart from, potentially, being illegal, because it deactivates vital emissions control equipment, it is also a false economy.
CDTi advises that such operations will lead to an increased likelihood of DPF blockages, meaning the DPF may need to be cleaned, or even replaced. Fuel economy and engine reliability issues may also result. The company adds that aftermarket Fuel Borne Catalysts offer genuine cost savings but only those offered by well-established quality suppliers. It claims that its offering, PatFluid, is formulated as a universal product that substitutes all four generations of OE Eolys fluid. The company asserts that Patfluid’s formulation ensures that it does not deposit additional ash into the DPF.
Yet, CDTi highlights a growing problem with new products entering the onboard DPF additive aftermarket. The company reports that it has tested these formulations and found that some of them contain less than 90% of the necessary active ingredients, compared to the original OEM Eolys. It concludes that, at such low levels, the performance of these products
is unlikely to match that of the original equipment additives. For comparison, CDTi reports that PatFluid’s formulation has a similar content range to OEM Eolys. While the cheaper products were available initially through online marketplaces, reports circulate of them being offered to garages by factors, so be on your guard.
You can also promote fuel additives that clean the DPF but be careful. Some types are sold as regeneration assisters, making them useful for drivers that cover multiple short runs. Additives for cleaning high soot loadings are different propositions, so check with the manufacturer, because the labels are not always clear.
Using the incorrect products and overdosing are several reasons why the aftermarket is experiencing a rise in DPFs that have melted internally. DPF Recovery told us that it has noticed a trend and highlights that repeated doses of such additives are responsible, along with repetitive forced generations. While decent diagnostic equipment is important, training is essential. DPF Recovery recommends the courses provided by both Frank Massey and Darren Darling and insists that specialists in this field are needed not just now but in the future.
In many ways, on-car cleaning is an easier customer-sell, because it avoids dismounting the DPF and the associated downtime. Naturally, success depends not just on the technician but also on the processes and chemicals used. Carwood reports that the cleaning fluid must not strip the coatings from the DPF monolith, because this will hamper future regenerations’ effectiveness. The company adds that on- car cleaning will only remove a fraction of the particles, if the cleansing fluid cannot reach all of the chambers.
DPF Recovery concurs, stating that on-car cleaning is viable for a low mileage vehicle that has a blocked DPF that is caused by other failed components, which tends to be responsible for nearly every DPF blockage, anyway. The main on-car DPF cleaning limitation is its inability to remove ash.
Both Carwood and DPF Recovery agree that, despite claims from certain companies, on-car cleaning does not remove ash deposits. Ash is the naturally-occurring remnant of soot that has combusted within the DPF – therefore, it cannot be burnt again. The same applies to cerium deposits from fuel additives, originating either from an onboard source, or those that are dosed manually. Generally, ash becomes an issue only after very high mileages, but this presumes that the car has been maintained on time and with correct-specification low SAPS oils, which promote reduced ash deposits. Even with low SAPS oils, BG Products reminds us that any mechanical problem, which causes higher oil consumption, will raise DPF ash loadings that reduce the soot holding capacity. Increased regeneration frequency is a typical indication.
Ash is removed only by back-flushing, because it cannot pass through the filter. Carwood emphasises that its off-car cleaning service removes not just ash and cerium but also oil and soot deposits, without damaging the precious metal coatings within the filter. DPF Recovery adds that off-car cleaning also permits inspection of the DPF’s internals. It also states that DPF manufacturers have concluded that there is no difference in performance, between a filter that has gone through its Flash Cleaner Machine process, and a new filter.
While it may seem that off-car cleaning is a hard service to justify, it is not in reality. Admittedly, turnaround may not be as quick as on-car cleaning, but a customer will only have to wait days, rather than weeks. With new replacement filters costing anywhere from several hundred to several thousands of pounds, Carwood maintains that fitting a professionally cleaned DPF is a much more cost-effective solution. If a customer encourages the fitting of a suspiciously cheap new filter, it is worth highlighting that non-OEM specification replacements may possess a low-grade (or a reduced
size) substrate that will degrade in the high regeneration temperatures. DPF Recovery adds that, because the precious metal content represents a significant percentage of a replacement DPF’s costs, an inexpensive aftermarket replacement may possess smaller catalysts with reduced quantities of precious metals.