Tips for aging well FAP and SCR

Gradually arriving at the regulations that regulate polluting emissions from engines, the after-treatment systems known under the names of DPF (particulate filter) and SCR (selective catalytic reduction) have spread in the last generations of engines gathered in the last stage. V. Many tractors and self-propelled machines are therefore now equipped with it. These new components, which may have been a source of failure in the first models installed, have since gained reliability. Catalytic converters are generally designed to be functional throughout the life of the tractor. As for DPFs, after having recommended changes to 3,000-4,000 hours for the first generations, manufacturers have greatly extended their lifespan, to over 6,000 hours, even for the life of the machine, under “normal” conditions of use. However, it is advisable to apply some good practices in order to preserve these accessories which can be very expensive when they need to be replaced. The standard exchange for a DPF starts at just over 1,000 euros for a small tractor, but can go up to 6,000 euros on a combine.

GNR and quality engine oil

The first element that can affect the proper functioning of these filters and catalysts is the quality of the fluids used. “In the case of abnormal failures of a DPF or SCR, we often ask the dealer to remove fuel and AdBlue from the immobilized vehicle, to carry out analyzes to verify its compliance. says Romain Lucas, Tractor Product Manager at Fendt. The arrival of the GNR coincided with the reduction in sulfur levels (10 times less than in the national fuel) and the increase in the cetane rate, developments necessary for the reduction of pollutant emissions and the proper functioning of depollution.

The use of low quality diesel, but also of engine oil containing a lot of sulfur, favors clogging of the DPFs »confirms Franck Schickele, from the company Technifap, which specializes in cleaning particulate filters. “Diesel fuel must meet EN 590 or ASTM D975 and have a sulfur level of less than 15 ppmsays Christophe Lebon, aftermarket project manager at the John Deere engine plant in Saran. Engines equipped with DPF and SCR can accept up to 20% biofuels in diesel. In addition, there is a risk of more frequent regenerations and damage to the filters. » Recommendations in terms of engine oil quality are more stringent for blocks with DPF, for which ACEA E9 or API CK-4 is most often required.

AdBlue additive for low loads

With regard to AdBlue, in addition to complying with the ISO 22241-1 standard, which guarantees a urea content of 32.5%, the quality of this solution, essential for the functioning of the SCR catalyst, depends on the storage conditions. By avoiding exposure to light and reducing temperature differences, AdBlue can be kept for almost two years. While a poorly stored product can degrade in six months. “Major suppliers like Yara and TotalEnergies offer two qualities of AdBlue: standard or additivesays Nicolas Morel, Product Manager for New Holland Tractors. The additive version is specially designed for low load applications where the engine does not raise the temperature sufficiently for optimal SCR catalytic converter operation. It is perfectly suited for course tractors and other material handling equipment generally operating at low speeds or idling. »

Careful filling of tanks

In addition to the quality and storage conditions, AdBlue is sensitive to pollution during filling. When refilling on a construction site, it is recommended not to use cans that have been used for other liquids. “As for the GNR, you have to keep the lid and the filling hole clean, so as not to let dust or dirt fall into the tank. It is also strongly advised not to remove the pre-filter present at the inlet of the tank in order to be able to use a high flow gun », warns Nicolas Morel. In terms of maintenance, the AdBlue circuit has a filter that must be changed at regular intervals. But when it is prematurely clogged, this can be a sign of excessive tank pollution, sometimes requiring the latter to be cleaned.

Respect DPF regenerations

Good practices are also essential to preserve the duration of the DPF. Its clogging level is electronically controlled by measuring the pressure at the inlet and outlet of the filter. In the case of machines whose engine is frequently used at low load, the low temperature rise of the engine does not promote passive regeneration and, consequently, causes the filter to clog more quickly. The engine computer can then prompt the user more regularly to validate the launch of a more advanced regeneration, ensuring an effective temperature rise to burn off the particles. This step is sometimes delayed by users, which can lead to premature clogging of the filter. “The risk is that the engine will lose power and consume more”, warns Christophe Lebon. In many cases, a stationary regeneration, to be performed for certain brands at the dealership, will solve the problem. “But when the DPF is really very sooty, cleaning or replacing is the only recourse. »

Clean instead of changing the DPF

“Users are not always aware that a DPF, despite its regenerations, remains a filter and that it is sometimes necessary to clean it, or even replace it in the long term. But unlike the usual filters that have a recommended lifespan, it is impossible to predict a deadline for intervening in a DPF”notes Romain Lucas, tractor product manager at Fendt.

Cleaning a clogged DPF is a technical solution that can be ten times cheaper than replacing the filter. Some dealerships turn to specialists such as Technifap, to whom they send dismantled filters for cleaning with water and pressurized air.

“We are selling a new, more compact and less expensive machine, which will allow some large dealers to equip themselves and do the cleaning themselves”, says Franck Schickele, sales manager at Technifap. Other service providers offer this service, some of which carry out cleaning without disassembling the filter. “It is imperative that the FAP is accessible so that we can inject the cleaning product, then the rinse product, restarting the motor at each step”, illustrates UltimAuto’s Ronan le Sciellour. However, cleaning remains a solution of last resort, because according to Christophe Lebon of John Deere, “Using chemicals and liquids under high pressure can sometimes cause structural damage to the filter. »

Leave a Comment