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Mahle Aftermarket offers fuel filter fitting advice

Mahle Aftermarket, a renowned component manufacturer and vehicle systems supplier, is dedicated to assisting technicians with common fitment problems in the workshop. KX191/1D and KX80D are two popular fuel filters manufactured by Mahle; however, care needs to be taken with their installation to prevent possible problems.

These two fuel filter modules, which Mahle manufactures as original equipment, are used in several million vehicles around the world, including a wide range of MAN Trucks. When correctly installed, they are very reliable and provide optimal filter performance. However, common complaints among customers after these filters have been replaced include difficulty starting the engine or an ECU error message appearing.


As a result Mahle has undertaken a detailed evaluation of the filter returns, which revealed that the cause is not the filter itself, but rather its incorrect installation.

The two most common installation errors are improper gasket handling and the centre post not being seated correctly, which leads to leakage. However, these errors are very easily avoided by following the correct procedure.

The improper gasket handling is simply that cover gasket is not coated with diesel fuel prior to installation or is damaged during the fitting onto the cover. To prevent this from happening, the technician needs to first coat the sealing components that are integrated in the filter with diesel fuel, then coat the gasket and slip the filter into the housing by hand onto the cover.

Another issue with the filter installation is the centre post not being seated properly after the cover is unscrewed. Sometimes during the removal of the cover, the centre post is inadvertently screwed out by several turns, which exposes the drain path, causing the filter to run dry. When starting the vehicle, the housing must first be pumped full of fuel, which causes a delay in the starting process. To prevent this problem, technicians need to ensure that the centre post is seated tightly before they install the new element and the cover.