By Gary Worrall

Fleet operators running Euro 4 or 5 compliant SCR engines need to monitor the additives in the exhaust after treatments to avoid expensive repairs, is the warning from the 2008 ATA Technical and Maintenance Conference.

Richard Brain, Regional Service Manager for PACCAR Australia, which includes DAF trucks, says even water in the tank can cause problems.

“Water in the tank dilutes the AdBlue, which means it is not working properly, and the sensors will detect this in the exhaust gases, and will tell the engine to de-rate itself, giving drivers less than full power,” Brain says.

Even more costly for operators is if chemical additives are mixed in with the AdBlue, Brain says, as they will attack the rubber seals, causing terminal damage.

“Replacing an SCR unit is over $5000 each, and this happens if diesel or other chemical contamination occurs," he says.

While not common, Brain says anyone who tries to ‘boost’ the performance of the SCR unit by adding diesel, methylated spirits or other chemicals will only cause it to fail, which in turn means a full replacement.

“These units are not repairable, they are a replacement item only, you throw them away and buy a new one,” Brain warns.