MAN Truck & Bus UK – which wrote to all customers with Euro 5 D26 engined trucks, suggesting a maintenance check be carried out on the EGR (exhaust gas recirculation) system – says the problem with Van Hool coaches is unrelated.
John Davies, MAN's head of UK service and support, explains that the numbers showing problems on buses and coaches are "proportionately very small", compared to those on its trucks.
Further, these engine issues are not the same. Being transversely mounted, the engines are equipped with cooling systems that are "entirely different" to those found in its trucks, he says, and it is the Van Hool cooling system that has been a "major factor in these failures".
Says Davies: "Trucks are where we have had the bigger issue, the problem being around the high-pressure intercooler on Euro 5 engines built up to the end of 2011, which can leak slightly internally."
He explains that, if undetected over a long period, this leak can lead to residues in the engine oil, which can occasionally impact the lubricant quality enough to result in crankshaft bearing failures.
"If vehicles are maintained properly, in line with recommended intervals, then such damage is very unlikely," he says. "Build-up of residues is slow and, if the oil is changed when due, it rarely contaminates the oil enough to create a problem," he asserts.
Problem engines are mostly D26 Euro 5 EGR 440bhp. There are some 6,500 of those operating in UK trucks but, according to Davies, the issues are on pre-2012 built units, bringing the numbers down to some 3,000.
"The vast majority of those have already had rectification work done, because we've know about the problem since early 2012 when we started replacing the intercoolers with the later version," says Davies.
"All the trucks under R&M have been rectified as standard. Whereas we were doing several intercoolers a month, it's now down to just a handful. That's why we issued the letter to customers that have not yet come forward, so we can close this issue down."
Davies also makes the point that nobody has paid for any high-pressure intercooler or EGR repairs resulting from this problem. "And where crank shaft bearing issues have been identified, we've covered them 100%, unless their workshops hadn't followed manufacturer's guidelines in terms of oil drain intervals."
MAN believes it has been quietly very proactive. "Our dealers have been very aware of the importance of checking coolant strengths and levels, as well as checking oil for contaminants. We have also been using that information to go back to customers where we find problems and suggest they look at the quality of oils they're using," says Davies.