Starter Motors Damage Scenarios
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
4.1 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. n Burning marks on connection overheating. cable and bolt n Connection bolt used incorrectly
as a “power distributor” for other pinion Starter consumers.
Remedies /avoidance: Starter housing Starter
n Tighten connecting nut of the n Fasten electric cable according to n Do not misuse the connections electrical connections with the manufacturer specifications in order of the starter motor as a node prescribed torque. to prevent cable from vibrating. for other electric components. A vibrating cable can damage Additional cables on terminal 30 n Ensure the connections are the insulation and result in the of the starter motor can lead to correctly positioned. nut becoming loose. A loose nut electrical contact resistances. n Ensure that the cables are laid increases the electrical contact according to the specifications resistance, resulting in excessive and the insulation cannot fray. temperatures and arcing. Freewheel clutch Freewheel Starter motors Starter
Loose connection has caused screw to overheat (housing melted) Loose connection has caused screw to overheat (housing melted) Short circuit on solenoid More 14 15 Solenoid Findings: Cause(s): n Missing earth cable (T31) to the 1.5 Solenoid engine and/or transmission.
n Corrosion on the earth cable. When n Burning marks and melted points n Insulation of the positive pole (T30) the engine is not running, there is an on the housing of the solenoid or supply line frayed. Short circuit to Housing melted electrical ground connection from starter motor the ground of the solenoid housing. the engine block to the pinion of n Connection bolt on positive pole n Connecting nut of terminal 30 the starter motor via the bearings, (T30) of solenoid discolored connection loosened. Either the crankshaft, flywheel, and ring gear.
nut was not correctly tightened If an oil film builds up in the crank- pinion Starter n Burning marks and plastic cover or the nut has become loose. shaft bearings during the starting of the solenoid melted process, the ground connection is n Positive pole (T30) supply line not n Insulation on supply line to starter broken. The starter motor speed fastened according to manufacturer motor charred drops significantly, possibly caus- specifications. The connecting nut ing a heavy break spark, which n Solenoid not working, pinion does has become loose as a result of may also damage the bearings. not engage, but starter motor turns the heavy copper cable vibrating.
n Solenoid not working, pinion does n Terminal 50 connection cable not engage, and starter motor only (coming from the ignition switch) Starter housing Starter turns momentarily inadvertently connected to the supply line to the starter motor (T30).
Remedies /avoidance:
n Check all electric cables, insulation, n Check that all earth cables on n Ensure the connections are cable grips, and connections for the vehicle and on the drive correctly positioned. damage. unit are connected correctly.
n Ensure that the cables are laid clutch Freewheel Carefully remove corrosion n When removing the starter motor, according to the specifications. from the connections. mark the cables and connections. Do not misuse the connections n Tighten connecting nuts of of the starter motor as a node n Remove corrosion from connections. the electrical connections with for other electric components. the prescribed torque. Starter motors Starter
Short circuit (burning marks on housing) Short circuit (burning marks on housing) More 16 17 Solenoid 1.6 Solenoid Findings: Cause(s):
n Thread on connection bolt damaged n Connecting nut tightened too much
Copper bolt damaged n Connection bolt stretched, in some cases with visible necking in the thread
n Connection bolt torn off Starter pinion Starter
Remedies /avoidance: Starter housing Starter
n Only tighten the nut on the copper bolt M8: 10 Nm ±2 Nm with the permitted torque: M10: 15 Nm ±3 Nm M12: 21 Nm ±3 Nm Freewheel clutch Freewheel Starter motors Starter
Nut on connection tightened too much and thread damaged Nut on connection tightened too much and bolt torn off Bolt thread overtightened More 18 19 Solenoid Findings: Cause(s): n Battery cable not secured firmly 1.7 Solenoid enough, in conjunction with strong vibrations. n Solenoid cover torn off n Transport damage.
Electrical connections broken n Solenoid cover broken n Connection bolt knocked during installation of starter motor. n Connection bolt completely torn out n If the starter motor still worked a few times, the plastic housing was only Starter pinion Starter cracked. Actuating the starter motor has increased the size of the crack.
Remedies /avoidance: Starter housing Starter
n Do not drop or throw the starter n When installing the starter motor, n Replace starter motor. motor. do not knock any components in n Secure cables to eliminate/ the engine compartment. prevent vibrations.
Freewheel clutch Freewheel Starter motors Starter
Terminal 30 connection torn out More 20 21 Solenoid Findings: Cause(s): remain in the extended position 2.1 Starter pinion and is slowly pushed back to the starting position by the rotating n All teeth on front face of the n Starter motor was started while combustion engine. pinion worn or abraded the engine was running. Pinion All teeth abraded on the front face n If the solenoid is activated for too cannot engage in the ring gear. n Heavy contamination on long via terminal 50 (T50), the tem- As a result, the front faces of all starter shaft and pinion perature increases, along with the the pinion teeth are damaged by internal resistance. This causes the n All teeth on front face of the the ring gear (operating error).
solenoid to lose power, resulting in pinion Starter pinion are worn or abraded n Starter motor engages automatically the pinion being pushed back to and the solenoid is thermally in the running engine. In case of the starting position by the rotating damaged heavy contamination, the pinion may combustion engine.
Remedies /avoidance: Starter housing Starter
n Check starter pinion and ring gear for n Check connection cable from ignition n Install a start-locking relay to damage and replace if necessary. switch for damage to insulation. prevent unintentional starting while engine is running. n Check that ignition switch works n If the starter motor is switched via correctly, replace if necessary. a relay, the relay must be replaced. Freewheel clutch Freewheel
30 50
86 30 Starter motors Starter
Relay
30 30 85 87 W 50
All teeth on front face of pinion worn Additional start-locking relay prevents starting while engine is running More 22 23 Solenoid 2.2 Starter pinion Findings: Cause(s):
n One or more pinion teeth are n Starter motor and freewheel clutch are Partially abraded on the front face abraded on the front face jammed—as a result, pinion is also stuck. When pinion is disengaged, n The damaged areas often only one or two pinion teeth are worn. have a blue discoloration
n Starter motor is usually jammed Starter pinion Starter (cannot turn in any direction)
Remedies /avoidance: Starter housing Starter
n Clarify cause of starter motor failure n Check ring gear on flywheel for n Clean drive end housing and (see damage scenario “Starter motor damage along entire circumfer- remove all foreign objects. spun out of control”) and replace ence and replace if necessary. n Check key switch and supply lines. starter motor. Freewheel clutch Freewheel Starter motors Starter
Individual pinion teeth are worn More 24 25 Solenoid 2.3 Starter pinion Findings: Cause(s):
n Cracks on one or more pinion n Mechanical overload as a result Teeth broken off teeth (forced rupture) of engine misfiring n One or more teeth completely n Mechanical overload due to starting broken off (forced rupture) when the engine is coming to a stop
n Pinion broken n Mechanical overload as a result of Starter pinion Starter using a battery that is too large or n In some cases, the shaft and/ a second battery or flange are also broken
Remedies /avoidance: Starter housing Starter
n Check valve timing and carburetion n Install a start-locking relay with a n Use correct battery size according and correct if necessary. time delay adjusted to the specific to vehicle manufacturer’s application. specifications. n After a failed starting attempt,
wait until the engine has come to a complete stop. Freewheel clutch Freewheel Starter motors Starter
Tooth broken off on starter pinion (mechanical overload) Broken starter pinion (mechanical overload) More 26 27 Solenoid 2.4 Starter pinion Findings: Cause(s):
n One or more pinion teeth are dam- n Foreign objects (bolt, spring, parts Tooth broken off aged in the center (forced rupture) of the clutch) have become loose and ended up between the ring n Starter shaft broken (forced rupture) gear and the pinion during the n Ring gear mechanically damaged starting process. This has caused the starter motor and ring gear to Starter pinion Starter become mechanically overloaded.
Remedies /avoidance: Starter housing Starter
n Replace starter motor. n Replace ring gear, as there will be n Remedy cause (replace vehicle severe damage to at least two teeth. clutch, pressure plate, and/or thrust bearing). Freewheel clutch Freewheel Starter motors Starter
Foreign object damage on pinion Pinion broken off Foreign object damage on pinion, starter shaft broken More 28 29 Solenoid Findings: Cause(s): n Freewheel clutch damaged as 2.5 Starter pinion a result of starting when the engine was coming to a stop n Blue discoloration on starter shaft n Pinion not disengaged after starting, n Freewheel clutch clogged or and pinion causing it to run along the ring gear Starter pinion and shaft discolored overheated (grease leaked) n Significant run marks on the front n Heavy dirt and dust contamination on and back of the tooth flanks the starter shaft, pinion, and/or helix
n Bearing bush of the pinion worn n Electrical defect in the solenoid Starter pinion Starter actuation n Heavy contamination in the vicinity of the starter jaw n Starter motor actuated for too long (starting problems, improper ven- n Freewheel clutch sluggish, jammed, tilation of the fuel system, etc.) or without power
Remedies /avoidance: Starter housing Starter
n Install new starter motor; check ring n Ensure that the starter motor is only n Clean drive end housing thoroughly. gear for wear and replace if necessary. actuated for a short period of time. n Clarify cause of contamination It is advisable to engage the starter n Check electric actuation of the starter (heavy contamination in the drive motor for no more than 30 seconds motor (key switch, cables, relay). end housing may indicate a worn and to then let it cool for 2 minutes. vehicle clutch). Freewheel clutch Freewheel Starter motors Starter
Blue thermal discoloration on starter shaft Significant run marks on pinion (front and back) More 30 31 Solenoid 3.1 Starter housing Findings: Cause(s):
n Starter motor flange broken n Mechanical overload as a Starter housing broken (forced rupture) result of engine misfiring n Shaft broken (forced rupture) n Starting when engine was coming to a stop n Cracks on one or more pinion teeth (forced rupture) Starter pinion Starter
Remedies /avoidance: Starter housing Starter
n Check valve timing and carbure- n After a failed starting attempt, n Install a start-locking relay tion and correct if necessary. wait until the engine has come with a time delay adjusted to a complete stop. to the specific application. Freewheel clutch Freewheel Starter motors Starter
Bearing cap on starter motor broken as a result of mechanical overload Starter shaft broken as a result of mechanical overload More 32 33 Solenoid 3.2 Starter housing Findings: Cause(s):
n Mechanical damage to housing n Transport damage
Starter housing broken or deformed n Mechanical damage to the rear n Starter motor damaged during bearing cap installation
n Starter motor tilted during assembly
n Starter motor dropped pinion Starter
Remedies /avoidance: Starter housing Starter
n Do not drop or throw starter motor n Install starter motor carefully and (even when still in the packaging). do not try to pull it into position with the fixing bolts. Freewheel clutch Freewheel Starter motors Starter
Transport damage to starter housing Transport damage to the flange Transport damage to the flange More 34 35 Solenoid 4.1 Freewheel clutch Findings: Cause(s):
n Grinding noises during starting n Starter motor is not suitable for the Grinding marks on the lock plate process vehicle. Starter motor pinion extends too far for this engine. Freewheel n Contact marks from the flywheel/ clutch comes into contact with the gear wheel on the front face of ring gear of the flywheel. the freewheel clutch
n Ring gear has come free of the pinion Starter n The lock plate is abraded, causing flywheel or was incorrectly mounted the rollers and springs to fall out on the flywheel. of the freewheel clutch n Flywheel is severely crooked or wobbly (assembly defect).
Remedies /avoidance: Starter housing Starter
n Only use the appropriate starter motor n Check that the ring gear is positioned n If it is unclear which starter for the application. correctly on the flywheel. motor is right for the application, compare all dimensions of the old starter motor and the stroke of the freewheel clutch (with pinion) with the new starter motor. Freewheel clutch Freewheel Starter motors Starter
Grinding marks from the flywheel on the guard plate of the freewheel clutch Grinding marks from the flywheel on the guard plate of the freewheel clutch More 36 37 Solenoid 4.2 Freewheel clutch Findings: Cause(s):
n Cracks on one or more pin- n Mechanical overload as a result Overrunning force uneven ion teeth (forced rupture) of engine misfiring. n One or more teeth completely n Mechanical overload due to broken off (forced rupture) starting when the engine is coming to a stop. n Pinion broken Starter pinion Starter
n Overrunning force uneven
Remedies /avoidance: Starter housing Starter
n Check valve timing and carburetion n After a failed starting attempt, n Install a start-locking relay and correct if necessary. wait until the engine has come with a time delay adjusted to a complete stop. to the specific application. Freewheel clutch Freewheel
5,000 µm
90°
180° Starter motors Starter
270°
Gauss 50%
Impressions on the cylindrical part of the pinion from the rollers of the freewheel clutch Roundness measurement on the cylindrical part of the pinion More 38 39 Solenoid Findings: Cause(s): n Freewheel clutch was thermally 4.3 Freewheel clutch overloaded. As a result, the plastic rolling element cage has melted n Freewheel clutch is jammed n Contamination and dust thicken and bonded with the springs and the grease in the clutch. Rolling rolling elements as it cooled down. Freewheel clutch sluggish or jammed n Significant wear marks on the front elements and springs are wedged and back of the pinion tooth flanks and jammed. n Heavy contamination in the n Freewheel clutch was thermally freewheel clutch
overloaded, for example, because pinion Starter n Grease in the freewheel clutch the pinion was engaged for too has become resinous and mixed long. As a result, the grease filling with dirt and dust has become resinous and the rolling elements and springs are sticky.
Remedies /avoidance: Starter housing Starter
n Replace starter motor. n Also install a start-locking relay. n Clarify cause of contamination (heavy contamination in the drive n Prevent the pinion from running n Clean drive end housing thoroughly. end housing may indicate a worn along the ring gear for too long. vehicle clutch). Freewheel clutch Freewheel Starter motors Starter
Pinion with freewheel clutch overheated, rolling element cage melted Significant run marks on pinion (front and back) Freewheel clutch heavily contaminated More 40 41 Solenoid Findings: Cause(s): n If the starter motor is actuated when 4.4 Freewheel clutch the engine is coming to a stop, the radial force generated by the n Combustion engine does not turn n Mechanical overload as a result rolling elements in the guide tracks Freewheel clutch no longer frictionally connected I during the starting process, although of engine misfiring. can be so large that the housing of the pinion engages and the starter the freewheel clutch bursts. As a n Freewheel clutch mechanically motor turns result, the rolling elements can no overloaded as a result of starting longer transfer sufficient force. At n Pinion can be twisted in both when the engine was coming the same time, the compressed
directions to a stop. pinion Starter lock plate is dilated and comes n Lock plate of the freewheel clutch free of the housing. Eventually, the is loose or has fallen off rolling elements and springs fall out.
n Rolling elements and springs are completely or partially missing
Remedies /avoidance: Starter housing Starter
n Install new starter motor; check ring n After a failed starting attempt, it is n Install a start-locking relay with gear for wear and replace if necessary. very important to wait until the engine a time delay adjusted to the has come to a complete stop before specific application. n Check valve timing and carburetion attempting to start the engine again. and correct if necessary. n Check electric actuation of the
starter motor (key switch, cables, relay). Freewheel clutch Freewheel Starter motors Starter
Housing of freewheel clutch overloaded and cracked Housing of freewheel clutch overloaded and cracked More 42 43 Solenoid Findings: n Pinion remains engaged for a long n The release fork mechanism 4.5 Freewheel clutch time even though the start- is sluggish. ing process has ended n Combustion engine does not turn n Freewheel clutch is overloaded as during every starting process, a result of the pinion being engaged Freewheel clutch no longer frictionally connected II although the pinion engages and in the ring gear for a long time. the starter motor turns Cause(s): n Grease leaks from the freewheel n Pinion can be twisted in both clutch as a result of thermal load. n Leaking engine or transmission oil directions. From time to time, rolling elements
combines with contamination to pinion Starter and springs become wedged, n Heavy contamination in the vicinity of form a sticky paste. This hinders the jammed, or worn. the pinion, freewheel clutch, and helix axial movement of the pinion on the shaft. The spring of the de-ener- n Dust, clutch abrasion particles, oil, gized solenoid pulls the mechanism and grease form a sticky paste in back more slowly or not at all. The the vicinity of the pinion, shaft, and pinion remains engaged for a long freewheel clutch period of time and rotates along the flywheel of the combustion engine. Starter housing Starter Remedies /avoidance:
n Install new starter motor; check ring n Locate and rectify cause of oil n Clean drive end housing thoroughly. gear for wear and replace if necessary. leakage (shaft seal rings on engine n Clarify cause of contamination and transmission, crankcase (heavy contamination in the drive ventilation on engine clogged). end housing may indicate a worn vehicle clutch). Freewheel clutch Freewheel Starter motors Starter
Starter motor and freewheel clutch heavily contaminated Freewheel clutch and helix heavily contaminated More 44 45 Solenoid Findings: n Commutator has broken down increases tenfold. If the combustion 5.1 Starter motor into its individual components engine is then brought to operating speed, the armature speeds increase n Rear bearing cap on the front flange n Brush holders and carbons have to well over 100,000 rpm (instead of of the starter motor twisted (can be been crushed 5,000 rpm). This creates such strong Starter motor spun out of control I easily identified by the two housing n If the starter motor is shaken, centrifugal forces that the armature screws) rattling noises can be heard and commutator are broken down n View through the bore of the drainage in the rear section into their individual components. tube: fibers and destroyed compo-
n Freewheel clutch jammed. Mechan- pinion Starter nents visible inside the starter motor ical damage due to starting when n Rear bearing cap destroyed Cause(s): the engine was coming to a stop.
n Fiberglass ring to reinforce the arma- n Freewheel clutch jammed. Mechanical n Overspeeds on the starter motor ture windings has been destroyed damage due to the pinion running armature due to damage to the (rear bearing cap is full of glass fibers) along the ring gear for too long. freewheel clutch. If the freewheel n Some copper elements of the clutch is jammed and the engine n Heavy contamination in the vicinity commutator have come free of the goes from the starting speed to idle of the pinion and shaft. assembly; brushes are heavily worn speed, the starter motor speed also Starter housing Starter
Remedies /avoidance:
n Install new starter motor; check ring n Check electric actuation of the starter n Install a start-locking relay to gear for wear and replace if necessary. motor (key switch, cables, relay). prevent inadvertent actuation of the starter motor. n After a failed starting attempt, it is n Ensure that the starter motor is only very important to wait until the engine actuated for a short period of time. has come to a complete stop before It is advisable to engage the starter Freewheel clutch Freewheel attempting to start the engine again. motor for no more than 30 seconds
Rear bearing cap opposite the flange twisted View into the drain hole and to then let it cool for 2 minutes. Starter motors Starter
Rear bearing cap broken; rotor and commutator spun out of control Commutator has started to break apart Armature winding and fiberglass ring of the armature spun out of control; New starter motor for comparison commutator and brushes destroyed More 46 47 Solenoid Findings: n Commutator has broken down n Overspeeds on the starter motor 5.2 Starter motor into its individual components armature due to damage to the freewheel clutch. n Rear bearing cap on the front flange n Rear bearing cap destroyed twisted (can be easily identified by n Freewheel clutch jammed. Mechan- n Armature windings heavily Starter motor spun out of control II the two inclined housing screws) ical damage due to starting when thermally discolored the engine was coming to a stop. n Melted areas on the bearing cap n Heavy thermal discoloration as a result of arcing (short circuit n Freewheel clutch jammed. Mechan- on the commutator between brushes and bearing cap) ical damage due to an excessively Starter pinion Starter long starting process. n Fiberglass ring to reinforce the arma- ture windings has been destroyed Cause(s): n At the time of the overspeeds (rear bearing cap is full of glass fibers) resulting in damage, the starter motor was still being supplied with n Brush holders and carbons have n Defect on the key switch or supply current. As a result, there may have been crushed line, resulting in the starter motor been a short circuit between the being permanently supplied with brush holder and housing cover. current.
- Starter housing Starter - Remedies /avoidance:
n Install new starter motor; check ring It is advisable to engage the starter n Check whether the engine and gear for wear and replace if necessary. motor for no more than 30 seconds all connected units can be turned and to then let it cool for 2 minutes. easily. n Check electric actuation of the starter motor (key switch, cables, relay). n Use the starter motor with the n Install a start-locking relay to pre- output indicated in the man- vent inadvertent and excessively n Ensure that the starter motor is only ufacturer specifications. long actuation of the starter motor. actuated for a short period of time. Freewheel clutch Freewheel
Rear bearing cap of the starter motor broken as a result of spinning out of Brush holder destroyed as a result of the armature spinning out of control control and melted after coming into contact with the brush (overspeed) Starter motors Starter
Commutator totally destroyed (extreme overspeed) Rear bearing cap of the starter motor melted after coming into contact Rear bearing cap opposite the flange twisted with brush More 48 49
6. Pole windings and Solenoid Findings: Cause(s): n With excessive power takeoff armature burnt at the starter motor, the starter motor speeds fall, while the n Pole winding insulation burnt or n Starter motor actuated for too current consumption of the starter shows a dark discoloration long (starting problems, improper motor increases to several times ventilation of the fuel system). n Armature discolored (annealing colors) its normal value. This results in n No or far too little rotation of the extreme heat being generated n Enamel insulation of the copper starter motor during the starting within the component. windings in the armature burnt process (engine jammed or sluggish).
or shows a dark discoloration n Damage process: starter motor pinion Starter n Vehicle was moved using the starter overheats, enamel insulation n Commutator thermally discolored motor. burnt, short circuit in the wind- n Burning marks on the surface of ings, and short circuit to ground. the commutator
- - Remedies /avoidance: Starter housing Starter
n Replace starter motor. n Ensure that the starter motor is only n Only use the starter motor to move operated for a short period of time. the vehicle in an emergency (e.g., if n Clarify and eliminate the cause of It is advisable to engage the starter the vehicle is stuck on a crossing). the sluggishness of the combus- motor for no more than 30 seconds tion engine and connected units. n After changing the fuel filter, do not and to then let it cool for 2 minutes. bleed the system by running the n Check whether key switch, relay, After the third unsuccessful attempt starter motor for a long time; instead, and cables were also affected. at starting, the starter motor requires bleed the system with a pump to a cooling period of 30 minutes. ensure that all bubbles are removed. Freewheel clutch Freewheel Starter motors Starter
Brown discoloration on the pole winding insulation (pole windings overheated) Starter motor armature thermally overloaded (discoloration) Burning marks on the commutator of the starter motor More 50 51 Solenoid Findings: n Corrosion in the starter motor (arma- n Starter motor installed in the wrong 7. Corrosion in the starter motor ture, commutator, brush holder, etc.) direction (drain hose facing up).
n Solenoid is not being energized n Drain hose is missing or defective n Water ingress as a result of the engine being cleaned incorrectly n Solenoid is energized but the with a high-pressure cleaner. main current for the starter motor is not applied Cause(s): n Damage to starter motor gaskets.
n Reduced starter motor speed n Starter motor was under water. Starter pinion Starter n Insufficient starter motor output (Starter motors are only splash-proof!)
n Corrosion in the solenoid, in the n Starter motor was actuated under retaining spring and plunger, water. Movement of the solenoid and and on the contact bridge pinion causes a pump movement.
- - Remedies /avoidance: Starter housing Starter
n Replace starter motor. n Ensure that the drain hose is n If the starter motor fails sporadi- seated properly. cally, install a new starter motor. n When cleaning the vehicle or engine, do not direct the water jet straight n Avoid driving through deep onto electric components. pools of water.
n Ensure that the correct installation n Never start the engine if the starter orientation is observed (drain hoses motor is below the water line. must always point downward). Freewheel clutch Freewheel Starter motors Starter
Corrosion on the solenoid Corrosion on the starter motor Corrosion inside the starter motor More 52 53 Solenoid Findings: n Despite a low mileage, carbon n Abrasion becomes paste-like (rather 8. Fuel or oil in the starter motor brushes are very heavily worn than dusty) and causes bridges and short circuits in the commutator n Insufficient starter motor output n Abrasion becomes paste-like (rather n Reduced starter motor speed Cause(s): than dusty) and can cause a short n Bridged copper segments of the circuit to ground at the brush holders commutator (carbon dust) n Ingress of fuel or engine oil n Leaks in the fuel filters and lines in the starter motor n Burning marks and discoloration
n Oil loss in the engine or transmission pinion Starter on the commutator n Brushes are saturated with fuel or oil, leading to increased brush sparking n Oil loss in the hydraulic system n Brushes soaked with fuel or oil and heavy abrasion n Abrasion particles from the carbon brushes are visibly adhered to the sides of the brushes and brush holders
- Remedies /avoidance: housing Starter
n Replace starter motor. n Clean engine and transmission n Check hydraulic pump, lines, and thoroughly. cylinders and replace or seal. n Locate and repair leaks in the engine. Freewheel clutch Freewheel Starter motors Starter
Abrasion particles from the carbon brushes on the commutator Oil in the starter motor Sticky abrasion particles from the carbon Mixture of oil and graphite dust in the brushes all around the brushes bearing cap More 54 55
9. Malfunctioning of the Solenoid Findings: n Support plate wedged n The consequences: starter motor Solenoid disengages the pinion too n Wear marks on the support plate forcefully. n Combustion engine does not start and washer If the pinion hits the stop ring too Direct drive starter motor (without reduction gear) n Starter motor turns too slowly n Large burr/ridge on the shaft groove powerfully, the shaft and commutator are pulled out of the armature piece n Starter motor turns sluggishly by piece. n Grease escaping at the protection Cause(s): Axial bearing disc at the back cap on the rear bearing cap end of the shaft is wedged and Starter pinion Starter inhibits the starter motor. n Axial bearing disc on the rear n The battery installed was too powerful. bearing cap jammed n An additional battery was subse- n Significant grinding marks on the quently installed in the vehicle. front face of the commutator n Connection cable from battery to n Significant grinding marks on the starter was replaced by a cable rear bearing cap that was too large.
- housing Starter - Remedies /avoidance:
n Replace starter motor. n Never use a starter battery that is n If possible, replace the direct drive too powerful. starter motor with a starter motor n Use starter battery in accordance with reduction gear. In a starter with the engine manufacturer’s n Use a cross section of the connec- motor of this type, the pinion shaft instructions. tion cable in accordance with the and armature shaft are separated specification. mechanically by the reduction gear. Freewheel clutch Freewheel Starter motors Starter
Support plate in the bearing cap heavily tarnished Support plate in the bearing cap heavily tarnished Support plate in the bearing cap heavily tarnished More 56 57
Glossary Glossary
Term Explanation Term Explanation
A starter motor is designed to be actuated for a maximum of 30 seconds per start. Armature Rotor of the starter motor. Operating time If actuated for longer, there is a risk of overheating. Rear cover of the starter motor. This cap contains the starter shaft and protects the starter motor against Bearing cap Most starter motors have electromagnetic coils that form a stator. In some applications, ingress of dust and liquids. Permanent magnet permanent magnets are installed in the stator housing instead of coils. Burning marks Melting of metallic components due to arcing. The pinion is a small gear wheel on the starter motor. During the starting process, Pinion it engages in the ring gear of the combustion engine and turns it. Carbon brush Transfers the currents to the sliding contacts (commutator) of the rotating armature. The plunger is the iron core of the solenoid. When the solenoid coils are supplied with current, Sliding contacts on the armature that conduct the current from the carbon brushes to the corresponding Plunger Commutator the iron core moves both the pinion and the spring-mounted contact bridge via the engaging lever. armature windings (coils). Pole winding Electromagnetic coils in the stator housing of the starter motor. Electrical switch in the solenoid. As very high working currents of several hundred amps need to be conducted Contact bridge in the starter motor, the contact bridge consists of a thick copper plate. Power output In the case of direct current, the real power P is the product of the voltage U and the current I. The amount of current that a starter motor takes from the battery. The current consumption is dependent Current consumption on the required torque, starter motor speed, and capacity of the battery. Pull-in winding Coil in the solenoid that pulls the plunger into the solenoid during the starting process.
The reduction gear (planetary gear) reduces the pinion speed, increasing the torque accordingly. Thanks to the Direct drive starter motor Starter motor without reduction gear—the shaft is made from one continuous piece. Reduction gear transmission ratio, the starter motor has a smaller design than a direct drive starter motor, with the same power output. Dust-proof Design that does not allow any contaminants to enter the starter motor in very dusty environments. Relay Electromagnetic switch that can turn large working currents on or off using small control currents.
Dust-protected Design that allows very few contaminants to enter the starter motor in dusty environments. Ring gear The ring gear is part of the flywheel. During the starting process, the pinion engages in the ring gear. Insulation made of synthetic resin for copper wires. Copper wires for coils usually come with enamel insulation. Enamel insulation As the insulation is very thin, more windings can be fitted into a small installation space. Sealed noseless starter motor Starter motor without a flange. The starter shaft is not countersupported at the front.
The speed necessary to bring a combustion engine to the point of self-sustained operation. Engaging The pinion teeth mesh with the teeth of the ring gear. Self-sustaining speed Generally, it is approximately one tenth of the idle-running speed. Engaging lever Rotatable lever via which the solenoid moves the pinion into engagement with the ring gear of the flywheel. Electromagnet that moves the pinion into engagement with the ring gear during the starting process Solenoid and then energizes the starter motor. The copper coils in the armature are also fixed in place using a ring made of glass fiber-reinforced plastic. Fiberglass ring The fiberglass ring prevents the windings from being flung out of the armature by centrifugal forces. Start-locking relay A relay that prevents the starting process from being initiated when the combustion engine is running.
Flange Special starter motor design in which the pinion shaft is additionally fastened and mounted on the front end. Starter motor Performance curve (torque, rotational speed) and current consumption of a starter motor. performance curve The flywheel (also known as the flywheel mass) is used to store the rotational energy of the combustion engine. Flywheel The flywheel compensates for the uneven acceleration of the crankshaft. The ring gear, via which the starter motor starts the engine, is fastened to the flywheel. Starter motor with flange Starter motor design in which the pinion shaft is additionally fastened and mounted on the front end.
The starter motor drives the pinion using a frictional connection. As soon as the engine reaches the point Stop ring Metal ring at the front end of the starter shaft, designed to restrict the pinion’s path of contact. Freewheel clutch of self-sustained operation, the engine speeds increase. The freewheel clutch interrupts the transmission of power in a backward direction from the engine to the starter motor. Torque of copper bolt M8: 10 Nm ±2 Nm, M10: 15 Nm ±3 Nm, M12: 21 Nm ±3 Nm The starter motor is generally grounded via the housing. In some applications (e.g., boat engines), Ground terminal the starter motor has a separate ground terminal. Transport damage External damage to the component caused by improper handling.
Helix thread on the pinion shaft. Its task is to cause the pinion to rotate slightly when it engages, On the bearing cap, there is a bore at the lowest position (ensure correct installation position). Helix Water drain allowing it to engage more easily. This prevents “tooth-to-tooth” positioning as far as possible. If condensation water collects in the starter motor, it can drain here.
Coil in the solenoid that pulls the plunger into the solenoid during the starting process and holds it there To prevent the water spray from getting into the starter motor via the water drain, Hold-in winding Water drain, drain hose throughout the process. the drain hose bends when water is spraying out.
Ignition switch The ignition switch is used to actuate the starter motor at terminal 50 on the solenoid.
A special paper band wound around the coils of the solenoid. If the solenoid is thermally overloaded Indicator band (actuated for too long), the indicator band becomes discolored. This makes it possible to verify that overloading has occurred.
The pinion is flexibly mounted with the meshing spring. This acts as a protection in case the pinion and Meshing spring ring gear are positioned tooth to tooth.
Mounting flange Front housing with which the starter motor is fastened to the combustion engine or transmission. 58 59
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