Starter motors Damage scenarios MAHLE Aftermarket GmbH Causes, remedies, and avoidance Pragstraße 26 – 46 70376 Stuttgart /Germany Phone: +49 711 501-0 www.mahle-aftermarket.com www.mpulse.mahle.com mahled-088/04.2020/EN 02 03 Preface Contents MAHLE is one of the most important develop- The same high quality guidelines are also applied to spare parts Design and function of a starter motor 04 5 Starter motor ment partners and manufacturers of engine com- for the aftermarket. ponents and systems in the automotive industry. 5.1 Starter motor spun out of control I 44 1 Solenoid Numerous checks during and after production ensure the con- 5.2 Starter motor spun out of control II 46 The engineers at MAHLE develop products of sistently high quality level of MAHLE products. If, however, 1.1 Malfunction I 06 the highest quality throughout the world in con- unexpected failures occur in practical operation, the causes are 6 Pole windings and armature burnt 48 1.2 Malfunction II 08 junction with engine and vehicle manufacturers. usually to be found in the engine environment. Operating or 1.3 Malfunction III 10 assembly errors, or unsuitable operating media, may also be 1.4 Electrical connections charred 12 7 Corrosion in the starter motor 50 causes of failure. 1.5 Housing melted 14 1.6 Copper bolt damaged 16 This brochure summarizes typical damage scenarios, describes 8 Fuel or oil in the starter motor 52 1.7 Electrical connections broken 18 their causes, and provides tips for avoiding similar damage in the future. This makes it easier to troubleshoot potential causes of 2 Starter pinion 9 Malfunctioning of the starter motor 54 damage. The advice provided in the brochure helps to ensure that our products work reliably in the long term and thus prolongs 2.1 All teeth abraded on the front face 20 the engine service life. Glossary 56 2.2 Partially abraded on the front face 22 2.3 Teeth broken off 24 Furthermore, our experts are also confronted with complex dam- 2.4 Tooth broken off 26 Our product portfolio 58 age scenarios that go beyond the scope of this brochure. In cases 2.5 Starter pinion and shaft discolored 28 where damage to our products cannot be readily diagnosed, we are more than willing to examine them at our premises and put Our information services 59 3 Starter housing together an expert damage report for you. Please contact your local sales partner. 3.1 Starter housing broken 30 3.2 Starter housing broken or deformed 32 4 Freewheel clutch 4.1 Grinding marks on the lock plate 34 4.2 Overrunning force uneven 36 Info at: 4.3 Freewheel clutch sluggish or blocked 38 4.4 Freewheel clutch no longer frictionally connected I 40 www.mahle-aftermarket.com 4.5 Freewheel clutch no longer frictionally connected II 42 04 05 Design and function 5 6 7 8 9 10 11 of a starter motor 4 1 2 3 The starter motor has the task of starting the combustion en- starts. To do this, the ignition switch must stop feeding current gine. To do this, the ignition switch needs to feed current to the to the solenoid. A spring then returns the iron core to its starting solenoid. The solenoid attracts an iron core (plunger), which position. This opens the contact bridge and cuts off the supply of mechanically (via a release fork) moves the starter pinion into current to the starter motor. The starter pinion then also returns engagement with the ring gear on the engine flywheel. At the to its starting position. Because the engine speed increases to end of its stroke movement, the iron core simultaneously closes idle speed as the starting process ends, but the pinion is still en- the contact bridge, which switches the starter motor on. In most gaged with the flywheel, a freewheel clutch between the starter types of starter motors, the starter motor then uses a reduction motor’s pinion and shaft prevents the starter motor from over- gear to crank the engine. The starting process is complete as speeding. soon as the combustion engine reaches its cranking speed and 20 19 18 17 16 15 14 13 12 Technical data Speed required in the combustion engine to reach the point of self-sustained operation approx. 70 –120 rpm 1 Location of pinion shaft 8 Contact bridge 15 Engaging fork Speed of the starter armature at the starting speed of the combustion engine approx. 3,000 – 6,000 rpm 2 Flange 9 T30 battery connection 16 Helix Idle-running speed of the combustion engine approx. 700 –1,200 rpm 3 Rolling element of freewheel clutch 10 Commutator 17 Meshing spring Current consumption of the solenoid approx. 50 –250 A 4 Mounting flange 11 Carbon brush 18 Freewheel clutch Current consumption of the solenoid holding coil approx. 20 – 80 A 5 Solenoid coil 12 Armature 19 Pinion Current consumption of the starter motor approx. 200 –2,500 A 6 Plunger 13 Pole winding 20 Stop ring Starter motor output 0.8 – 9.0 kW 7 Solenoid 14 Reduction gear 06 07 Solenoid Findings: Cause(s): n Defective earth cable or corrosion 1.1 Solenoid on one of the screw connections n No overheating of the coil in the n Combustion engine or auxiliary Malfunction I solenoid aggregate is stuck n Solenoid is energized momentarily n Starter battery too weak: when but the starter motor does not turn the starter motor is switched on, the voltage fails n The solenoid is partially energized Starter pinion Starter and then released again immedi- n Contact bridge in solenoid burnt ately; a clicking noise can be heard n Contact bridge corroded n The solenoid does not respond n Poor contact of the connecting cable when supplied with current with the starter motor and battery Remedies /avoidance: Starter housing Starter n Charge battery or replace if necessary. n If the solenoid has burnt through: n In case of a defective solenoid: check ignition switch and cable replace starter motor. n Check whether the combustion engine to starter motor. and auxiliary aggregates can be n Never aim jet of high-pressure turned mechanically. n In case of corrosion, check at what cleaner directly onto starter point water has entered the starter motor and cables. n Check all cables for damage and motor. connections for corrosion. n Only use starter motor to move the vehicle in an emergency. Freewheel clutch Freewheel Contacts burnt Starter motors Starter Contact screw overheated and melted into cover Corrosion on the contacts Corroded ground strap Solenoid (opened) not overheated More 08 09 Solenoid Findings: Cause(s): n In larger starter motors, the motor is 1.2 Solenoid already set into rotation with reduced power via the solenoid connected in n Indicator band discolored n Coil in solenoid burnt through or series. In tooth-to-tooth position, the short circuit in the windings. solenoid does not engage, which Malfunction II n Coil in solenoid overheated soon leads to overheating. n Starter motor actuated for too long. n No response from solenoid when supplied with current n Starter motor jammed (engine or auxiliary aggregates jammed). n Indicator band inside solenoid pinion Starter is blackened n Starter motor overloaded (vehi- cle moved using starter motor). n Burning smell in the vicinity of the solenoid Remedies /avoidance: Starter housing Starter n Actuate starter motor for a maximum n For example, after changing the fuel n Only use the starter motor to move of 30 seconds, then allow it to cool for filter, do not bleed the system by run- the vehicle in an emergency (e.g., if at least two minutes before the next ning the starter motor for a long time. the vehicle is stuck on a crossing). starting attempt. It makes more sense to bleed the n With heavier starter motors, stop system using a pump to ensure that the starting process immedi- all bubbles are removed. ately if the motor does not turn (tooth-to-tooth position). Freewheel clutch Freewheel Starter motors Starter Solenoid overheated, indicator band heavily discolored Solenoid overheated, indicator band slightly Solenoid significantly overheated and burnt Fixing bolt of the solenoid with burning marks discolored from overheated solenoid coil More 10 11 Solenoid Findings: Cause(s): n Heavy contamination in the sole- 1.3 Solenoid noid prevents movement of the plunger. This means that the pinion n Starter motor is not working n Heavy contamination in the sole- does not engage and the starter noid was compacted in the rear of motor does not switch on. Malfunction III n Solenoid pulls the pinion out, but the solenoid by the plunger. Thick does not engage in the starter motor dirt deposits prevent the plunger n Solenoid does not pull the pinion out from moving right to the end. The distance is no longer sufficient, Starter pinion Starter contact bridge is not closed. Remedies /avoidance: Starter housing Starter n Install new starter motor. n Clarify cause of contamination (heavy contamination in the n Clean drive end housing thoroughly. drive end housing may indicate a worn vehicle clutch). Freewheel clutch Freewheel Starter motors Starter Dirt inside the solenoid More 12 13 Solenoid Findings: Cause(s): n Excessive current consumption due 1.4 Solenoid to ground terminal on starter motor. n Connection cables not fastened n Solenoid cover melted n Connection cable loose. Increased securely enough to vehicle. If electrical contact resistance and arcing on Electrical connections charred n Connection bolt in cover charred cables start to vibrate, the nut at the connecting line produce local connection may begin to loosen.