Professional tips: Service and repair BERU diesel instant start system ISS correctly
For eight years the BERU Instant Start System (ISS) has been providing an "SI engine like key start" for compression-ignition engines. Now more and more ISS vehicles are coming to workshops for maintenance and repair work.
(Ludwigsburg, 4 September 2008) The first generation of the BERU diesel instant start system (ISS) has been on the market since 2000. Since then it has been providing ex works an "SI engine like key start" in vehicles manufactured by Audi, BMW, Chevrolet, Hyundai, Isuzu, Jeep, Mercedes-Benz, Opel, Seat, Skoda and Volkswagen. The US manufacturer General Motors has been using ISS in its light trucks since 2004. Eight years after the series production launch, vehicles are now due for replacement or repair work. For workshops this means: More and more vehicles with BERU ISS technology are being serviced.
BERU ISS: Replacement tips from the professional for professionals
At first glance BERU ISS glow plugs look deceptively similar to their predecessors, however they differ greatly from them with regards to technology. As electronically controlled glow plugs (GE types) they have a heat-up time of only one to two seconds at - 25°C and require significantly less energy than conventional glow plugs. A microcontroller in the electronic ISS control unit regulates the glow currents according to the engine requirement. The electronic control allows, amongst other things, systematic intermediate heating, in idling or after longer trailing throttle, for example. Advantages: a permanently reliable and safe combustion process, prevention to a large extent of warm-up problems, irregular running, diesel knock and excessive vibrations.
For individual control BERU uses power semiconductors which are designed for voltages between 4.4 and 5 volts depending on type and vehicle manufacturer. For workshop professionals this means: At a current feed of 12 volts ISS glow plugs would be immediately destroyed by the overvoltage. Therefore: always err on the side of caution and before testing a heating unit, it is essential to check whether the engine is fitted with BERU ISS.
ISS glow plugs which are due to be replaced can be quickly detected by the error message on the cockpit display or in the workshop by means of the onboard diagnostics (OBD). Günther Vogt, BERU department manager trade/technology, recommends the following procedure: "If the vehicle in question has clocked up 100,000 kilometers or more, you should immediately replace the complete set of ISS glow plugs because of the often considerable installation expenditure. If the engine has clocked up just under 60,000 kilometers, it is usually necessary to replace the defective glow plug only. As it takes a maximum 4.5 hours to replace the plugs, I would advise workshop customers always to have them all replaced." Which ISS glow plugs and glow time control units are suitable for which vehicles can be found in the current BERU spark/glow plug application list.
Don’t just unscrew: Have ISS glow plugs installed professionally
A suitable torque wrench is essential for removing and inserting the slender quick-start glow plugs. Above all observe the stipulated torque: 15 Nm for ISS glow plugs with M10 thread, 12 Nm for M9 glow plugs and 10 Nm for ISS glow plugs with M8 thread. BERU professional Vogt knows from many years of hotline experience: "If the tightening torque is too high, the ISS plug may be twisted off and the annular gap of the glow plug may be closed unnoticed. It will then wear out prematurely due to overheating. This is usually the reason if an ISS spark plug fails shortly after installation." The annular gap may also become clogged by carbonization from the engine. Consequence: The self-control of the ISS glow plug malfunctions, causing the plug to fail. Vogt: "If you occasionally fill up with synthetic fuel, this carbonization can be simply and effectively prevented." Also important: Prior to installation, brush the thread and shaft of the glow plugs with BERU glow plug assembly grease. This facilitates installation and subsequent removal of the glow plugs.
When the ISS glow plugs have been replaced, reset the vehicle error memory. Or, preheat the ISS system five to seven times: The intelligent ISS control unit learns from this and the error message disappears.
