Delco -Remy
SERVICE MANUAL
ANALYSIS OF ELECTRICAL TROUBLES 1920's into 30's
GENERATORS
Internal Open Circuits-Test. Remove cover band and examine the generator, as well as the
cut-out relay.
Remedy-(a) Gummy commutator. Clean with No. 00 sandpaper, and if brushes are badly
worn replace them.
(b) Brushes worn or not seated properly. Replace or seat brushes.
(c) Brush arms sticking or springs weak. Remove and free the arms if binding or
replace the springs.
(d) High mica on the commutator. Remove the armature, turn down and undercut the
commutator.
(e) Solder thrown. Remove generator, solder coil leads in commutator and check all
external connections, charging rate and cut-out relay adjustment.
(f) Loose internal connections at the generator or third brush arm. Tighten the
loose connections.
(g) Defective relay. Burned windings, spring broken or points burned and pitted.
Check with test points as well as visual inspection and repair or replace damaged
parts.
Internal Terminal Lead Grounded or Open-Test. Check with test points the lead from
the generator to the ungrounded brush arm. Brushes must be lifted to make ground test.
Remedy-Repair or replace lead.
Cut-Out Relay Not Operating-Test. With the engine running, close the contact points
on the cutout relay and if the ammeter indicates a charge, check the internal circuits
of the relay with test points.
Remedy-(a) The voltage coil in relay is open, causing the points not to close. Replace the
relay.
(b) Open current coil in relay preventing charging current from passing through
to the battery. Replace the relay.
(c) Relay out of adjustment. Remove and adjust the relay. (See Section IV.)
Insulated Brush Arm Mounting Stud Grounded- Test. Insulate the generator
brushes from the commutator by placing a strip of heavy paper under the brushes.
Use the test points between the insulated brush arm to ground. If the test lamp
lights, the brush arm mounting stud is grounded.
Remedy-Replace the entire brush arm mounting plate.
Open Field Coil Circuit-Test. Insulate the generator brushes from the commutator
by placing a strip of heavy paper under the brushes. Use the test points at the
terminals of the field coils. An open circuit is indicated by the test lamp not lighting.
Remedy-Remove coils and repair or replace.
Shorted or Open-Circuited Armature Windings- Test. Use six volt battery and let
generator run as a shunt motor. If it does not run steady, having even torque,
the armature is open or shorted. The same test can be made by inserting an ammeter
in the generator circuit. If the ammeter needle flickers and does not become steady,
the armature is open or shorted.
Remedy-Replace armature unless cause of trouble is a minor defect and can be repaired.
Field Reversed-Test . Use a six volt battery. Let the generator run as a shunt motor. If
the direction of rotation is opposite from normal the field is reversed. (See car data
sheet-Section VI.)
Remedy-Exchange the field connections.
Generator Charges Below Normal Rate-Test. Remove cover band and examine the
generator for thrown solder, gummy commutator, high mica and weak brush springs.
Remedy-(a) Solder thrown from commutator. Remove armature and solder commutator.
(b) Commutator gummed. Clean the commutator with No. 00 sandpaper. Avoid
excessive lubrication which may also cause this trouble. Replace brushes if oil
soaked.
(c) High Mica. Remove armature and turn down and undercut the mica.
(d) Replace weak brush springs.
(e) Check third brush position.
Incorrect Charging Rate-Test. Attach portable ammeter in charging circuit at generator
terminal and check readings with those specified for the particular unit
Remedy-Charging rate can be increased or decreased within certain limits by moving third
brush in direction of armature rotation or against armature rotation, respectively.
Open Thermostat Contacts-Test. When generator is cold the thermostat contacts should be
closed. To check for this trouble remove the field lead and attach it to ground on frame of
the generator. If points are open charging rate of generator will increase.
Remedy-Clean contacts. If trouble is not corrected replace thermostat.
Open Thermostat Resistance-Test. Failure of generator to show charge after becoming hot
indicates open resistance unit. Remove field lead and separate contact points with piece of
heavy paper. Place test points on resistance unit mounting screws. If lamp does not light the
resistance is open.
Remedy-An open resistance unit must be replaced.
Drive Belt Loose-Test. Inspect generator belt for looseness. Armature and fan should not
revolve when relay points are closed by hand with engine stopped. Engine must be driven at
high speed in order to get the generator to reach a maximum charge.
Remedy-Tighten the belt adjustment.
Bad Connections in Charging Circuit-Test. Check the external connections, using voltmeter
tests.
Remedy-(a) Loose or poor connections in the generator circuit. Clean and tighten the
connections.
(b) Poor internal connections in the ammeter. Either repair or replace the ammeter.
Battery Becomes Gradually Discharged.-Test. Disconnect battery ground connection and
connect an ammeter in series from the battery to the ground. Have all switch levers in
"OFF" position. There should not be a reading on ammeter. If there is a ground in the
cranking circuit, or in the battery, check the following for leaks.
Remedy-(a) Chafed insulation on wires. Locate and repair or replace cable.
(b) Leaks thru armored cable around leads. Replace lead.
(c) Top of battery wet. Clean with ammonia or baking soda solution, and dry
exterior parts of battery.
Abnormal Driving Conditions-Test. Check the amount of night driving, length of day runs,
amount of time car stands with lights on, average number of starts per day, and any other
circumstances peculiar to operation.
Remedy-Adjust the charging rate to conform with the driving conditions.
Excessive Electrical Accessories-Test. Check the current consumption against that used by
a standard car.
Remedy-Discontinue use of equipment not actually required.
Excessive Use of Current for Cranking-Test. Try cranking by hand. If the engine is too stiff
to be moved by hand, there is an excessive use of current during electrical cranking
operation.
Remedy-(a) Engine bearings tight. Adjust the tight bearings.
(b) Excessive cranking required because of poor carburetor adjustment or choking.
Correct adjustment or operation.
Throwing Solder from Commutator-Test. Check ammeter to see if it is reading low when
generator is charging. If this test is taken at the generator terminals, the portable
instrument will read 2 amperes higher than the dash ammeter.
Remedy-(a) Third brush advanced too far. Retard until normal rate is obtained.
(b) Thermostat contacts not opening. Replace thermostat. Brush Arm Sticking-
Test. Check spring tension of generator brush arms according to data given for
unit in question. The resultant arc beneath the brush on a sticking arm causes
high local temperature.
Remedy-Free brush arms.
Open or Loose Connections in Charging Circuit- Test. Check connections in charging
circuit.
Remedy-(a) Poor contact in combination switch. Remove and repair switch.
(b) Loose terminal nuts or poorly soldered connections. Tighten and resolder.
(c) Cutout relay contacts not closing. Test relay circuits and make necessary
repairs or adjustments. See that base of relay is grounded.
Noisy Operation-Test. Revolve armature by hand and observe if it drags or makes scraping
sound on pole pieces.
Remedy-(a) Bearings worn or broken. Remove the unit and replace the bearings. Also
replace armature if it is damaged.
(b) Pole pieces too close to armature. Tighten pole piece screws.
Brushes Squeaking-Test. While engine is running, lift each brush from commutator in turn
until brush squeak is located.
Remedy-Re-sand the brush or replace it, making sure that the specified brush for the unit is
used.
Not Operating-Test. Remove cover band and inspect motor for burned commutator, thrown
armature windings or sticking brush arms.
Remedy-In case of such trouble remove unit and repair or replace the armature or free
brush arms. If no troubles are apparent, proceed with tests in the order given.
Battery Weak-Test. First apply a voltmeter across the battery terminals and take a
reading while depressing the starting pedal. Voltage of the battery should not drop below
4.0 volts. A weak condition of the battery is also indicated by the lamps dimming or going
out entirely when attempting to crank.
Remedy-(a) Undercharged. Have battery charged from outside source.
(b) Defective cell or cells. Have battery repaired or replaced. Connections Loose,
Broken or Corroded-Test. If the battery is in good condition and the starter
refuses to crank the engine, close the starting motor switch, holding it down
for one-half minute to heat up any loose connections. Feel all cranking circuit
connections and if any are found warm they are imperfect. If the lamps dim or
go out entirely, when starting motor switch is closed, the poor connections will
be found between starting motor switch and battery.
Remedy-(a) Paint or rust at ground connection. Clean thoroughly.
(b) Terminal nuts loose. Tighten.
(c) Terminal poorly soldered. Resolder.
(d) Battery terminals corroded. Remove and clean, afterwards applying Vaseline.
A solution of baking soda and water is excellent for cleaning battery terminals.
Tight Engine-Test. Crank engine by hand. If crank cannot be turned at all or seems tighter
than usual, the load on the starting motor will be excessive and prevent normal cranking.
Remedy-(a) Engine bearings too tight, or engine stuck due to overheating or rusted internal
parts. Have engine properly adjusted.
Internal Trouble-Test. If previous tests indicate that the trouble is within the starting
motor, remove unit from car and inspect for trouble by running it at no load with a battery
of voltage specified for the unit. If motor runs make stall torque test. If it does not run
check armature, field coils, brushes, brush arms and internal connections.
Remedy-(a) Armature windings defective. Repair windings or replace armature.
(b) Field coils grounded or open circuited. Check with test points and repair or
replace.
(c) Internal connections loose or cold-soldered. Clean and tighten or resolder.
(d) Brushes worn or broken and not touching commutator. Replace and reseat by
sanding pair.
(e) Brush arms sticking. Clean and re
(f ) Bearings worn or sticking. Replace.
(g) Burned commutator. Turn down and undercut mica.
(h) Broken or weak brush arm springs. Check with spring tension scale and replace
defective springs.
Starting Motor Switch Defective-Test. When there seems to be no current flowing in the
starting system, connect outside terminals of starting motor switch with a short piece of
heavy cable. If starting motor then cranks, switch is not completing circuit.
Remedy-Starting motor switch contact burned or broken. Clean contacts or replace switch.
Bendix Drive. Will Not Engage with Flywheel- Test. Close starting switch. If motor runs,
but the Bendix pinion (is not engage with flywheel, check the condition of Bendix shaft and
parts.
Remedy-(a) Grit or gummed oil on Bendix shaft. Remove unit and clean.
(b) Drift plunger in counterweight on Bendix pinion has too much spring tension.
Remove unit, and head-over very slightly the plunger pin where it projects
thru gear weight.
Noisy Bendix-Test. Make visual inspection of starting motor mounting.
Remedy-(a) Loose pilot mounting screw permitting starting motor to become loose in
flywheel housing. Tighten screw.
Pinion Locking in Flywheel-Test. If locking or pilot mounting screw is not loose or broken,
remove unit and inspect.
Remedy-(a) Battered gears. Repair or replace.
(b) Gears meshing too deeply. Correct line-up of starting motor on engine.
(c) Burned or eccentric commutator. Turn down and replace brushes.
(d) Worn starting motor bearings. Replace.
Disconnected or Broken Clutch Drive-Test. Make inspection of entire shifting mechanism.
Remedy-(a) Badly worn or broken parts. Replace the drive clutch.
Incomplete Circuit Thru Switch-Test. When there seems to be no current flowing in the
starting system, check switch plunger adjustment.
Remedy-Switch plunger adjustment on certain types incorrect. Adjustment on switches
operated in this manner should be such that the contacts close during the last 18 inch
travel of the starter pinion.
Drive Clutch Slipping-Test. Depress starting pedal. If motor armature revolves with gears
normally meshed and engine is not cranked, the drive clutch is slipping.
Remedy-Remove unit and replace clutch.
Drive Clutch Sticking-Test. If armature windings are thrown and field coils possibly
damaged, the drive clutch has been sticking, causing armature to be driven at excessive
speeds by the flywheel.
Remedy-(a) Remove unit and replace clutch.
(b) Check starter pedal linkage and return spring and free slightly if necessary.
Binding Shift Mechanism-Test. Operate the starting pedal to ascertain whether
shift is sticking or binding.
Remedy-Remove the unit from car and disassemble drive, cleaning and lubricating shaft
spline and drive parts.
Engine Fails to Fire-Test. Make visual inspection of exposed wiring in both primary and
H.T. circuits, looking for loose, broken, or disconnected wires, terminals or clips.
Remedy-Repair any visible cause of trouble. If no troubles are apparent, proceed with
tests in the order given.
Open Primary Circuit - Test. Switch ignition "ON" and place a screw driver on terminal
to ground. If no spark or flash is obtained, check for an open circuit.
Remedy-(a) Open primary circuit between battery and the distributor terminal which
includes the ammeter, also ignition switch contacts. (Check with jumper
lead between contacts on switch.) Repair or tighten any loose or broken
connections.
(b) Resistance unit burned out. Replace unit and check entire generator system
for loose connections which might increase voltage in ignition and lighting
circuits.
(c) Open primary winding in ignition coil. Replace ignition coil.
Check Current Thru Contacts-Test. Remove distributor head and separate contacts by
hand, observing any arc between contacts. If a small amount of normal arc is not observed,
look for open circuit in distributor, or for a shorted condenser.
Remedy-(a) Poor ground connection of contact arm spring inside distributor. Make positive
ground.
(b) Burned or dirty contact points. Clean and adjust contacts.
(c) Shorted condenser. Check with test points. Replace condenser.
(d) Ground at some point between terminal in the side of distributor cup and
contact points. Make visual inspection or use test points. Remove the ground, installing new
parts if necessary.
Trouble in Coil Circuits-Test. Remove H.T. lead from center terminal of distributor cap and
hold it one-fourth inch from ground. Crank engine by hand or with starter. If good H.T.
spark is not obtained, check secondary winding of ignition coil, and H.T. lead between
ignition coil and distributor cap.
Remedy-(a) Trouble in secondary winding of coil. Check by substitution of a known good
coil. Replace ignition coil.
(b) Ground in H.T. lead between coil and distributor. Replace lead.
Trouble within Condenser-Test. Check by substituting a known good condenser and noting
the effect upon the ignition.
Remedy-(a) Weak condenser. Replace.
(b) Open condenser. Replace.
Contacts Not Properly Adjusted-Test. Check contact surfaces, their maximum separation,
and ability to close properly.
Remedy-(a) Burned surfaces should be cleaned with an oil stone.
(b) Wrong adjustment. Adjust separation at limits specified for the particular unit.
Incorrect Ignition Timing-Test. Crank engine by hand until No. 1 piston is on T.D.C.
compression stroke. Retard the spark. Look at contact points in distributor. They should
be just separating. This method of timing the engine will give a satisfactory check in the
absence of specific instructions from car manufacturer.
Remedy-Incorrect timing. Re-time according to instructions given by car manufacturer.
Miss in One or More Cylinders-Test. With engine running, remove the H.T. lead from the
spark plugs, one at a time, and hold the lead terminal one-fourth inch from the cylinder
block and note H.T. spark.
Remedy-(a) If no spark is observed in any case, the cause of the trouble will be found in a
grounded H.T. lead between distributor head and plug, or a burned distributor
cap. Remove ground or replace cap.
(b) If a good spark is observed in each case and the miss is still present, the trouble
will be found in a fouled or defective spark plug, or in poor engine compression
in one or more cylinders.
Engine Misses Irregularly-Test. Remove the H.T. lead from terminal of ignition coil and
hold it about one-forth inch from the coil terminal, and note the spark at various engine
speeds.
Remedy-If the sparks pass regularly without any missing, the trouble will be found due to
defective insulation on leads in H.T. lead manifold or due to defective spark plugs or engine
trouble. Make repairs or replace parts.
Engine Overheats-Test. Check ignition timing and position of spark lever at steering wheel
during driving. Check the automatic spark advance mechanism for interference by twisting
the rotor assembly after removal of the distributor cap. Also check the circulation of the
cooling system.
Remedy-Time engine correctly and operate engine with proper spark advance. Repair
automatic spark advance mechanism or correct engine cooling system.
Lamps Do Not Burn-Test. Turn the ignition switch "ON." If the discharge is not indicated
on the ammeter, look for an open circuit.
Remedy-Loose or broken connections between the battery and the combination switch.
Trace and repair the circuit.
No Contact Through Lighting Switch-Test. Turn the lighting switch lever to all positions and
find that none of the lamps burn.
Remedy-(a) Contacts on current limit relay being held open. Reach under dash and close the
contacts; if lamps burn, remove and adjust current limit relay.
(b) Internal switch connections open. Short around the switch with a jumper wire.
if the lamps burn, remove and repair switch.
Ground in Lighting Circuit-Test. Turn the lighting switch lever on and the current limit
relayvibrates.
Remedy-Ground in the lighting circuit or lamp socket. Change the switch lever positions, or
disconnect the leads at the back of the switch one at a time until the current limit relay stops
vibrating. Repair the ground.
Lamps Burn Out or Have Short Life-Test. Check conditions of battery charge and look for
loose connections at some point in the charging circuit causing high voltage in the lighting
circuit.
Remedy-(a) Battery overcharged. Reduce the charging rate of the generator slightly.
(b) Loose or open circuit in the charging circuits. Inspect and tighten all
connections.
(c) Corroded battery terminal. Clean with a solution of baking soda and water
and afterward tighten and apply Vaseline to prevent corrosion.
Out of Adjustment-Test. Sound the horn.
Remedy-Adjust.
Cracked Diaphragm.-Test. Horn will have a low or tinny sound. Look thru the projector or
face plate to ascertain whether diaphragm is cracked.
Remedy-Replace with new diaphragm.
Low Battery-Test. If horn has weak tone check the voltage at the horn terminals, and
check the specific gravity of the battery solution. Check current and voltage readings
of the horn.
Remedy-Recharge battery.
Undersize Wire in Horn Circuit-Test. Horn will give weak signal while mounted on the car
and will operate normal when connected in a standard circuit.
Remedy-Measure the wire in the horn circuit and replace with new wire if undersize. Do not
use wire smaller than No. 14, B and S gauge (.065 inches or 1.651 millimeter diameter).
Poor Contact in Horn Button-Test. Horn will give good signals occasionally and poor or no
signals at all other times. Shunt around the horn button to determine conclusively whether
trouble is in the button.
Remedy-Replace push button or clean the contacts.
Bad Connections in Horn Circuit-Test. Examine wiring connections. Connect separate test
leads from battery to horn.
Remedy-Clean and tighten all bad connections.
Loose Collar Screws or Nuts-Test. Horn usually has a rasping sound when vital parts are
loose.
Remedy-Tighten all collar screws, mounting studs, and nuts. All nuts should have lock
washers underneath them.
Open, Shorted, or Grounded Field-Test. Horn will not sound, ammeter shows no discharge
in case of an open field coil and excessive discharge in case of a shorted or grounded field
coil. Use test points and lamp to check this circuit.
Remedy-Replace coil if defective.
KLAXON HORNS (Hand Operated)
Loose Anvil-Test. Horn will not produce a clear tone and the diaphragm is not cracked,
therefore, remove the projector and inspect the anvil.
Remedy-Replace the diaphragm.
Worn Gears or Broken Pinion-Test. Push rack locks when pressed down.
Remedy-Replace gears and pinion or complete horn if gears are not obtainable.
Push Rack Teeth Stripped-Test. Press down push rack to find out whether it meshes with
the pinion or remove screw in the bottom of the push rack and inspect.
Remedy-Replace push rack or complete horn.
Clutch Worn or Broken-Test. If the rotor does not run, or will only turn when push rack is
on its downward travel, examine the clutch for worn or broken parts.
Remedy-Replace the clutch.
KLAXON HORNS (Motor Driven)
Loose Rotor or Anvil-Test. Remove the projector and inspect the rotor and anvil.
Remedy-If the anvil is loose replace the diaphragm and if rotor is loose tighten rotor screw
or nut. Replace the rotor if badly worn.
Worn Bearings-Test. Try armature for side play.
Remedy-Replace armature or ball bearing or both depending on the amount of wear.
Armature Rubs Pole Pieces-Test. Examine armature core.
Remedy-Replace armature if shaft is bent. If armature is alright tighten frame and field
assembly to horn base. Replace the frame and field assembly if this does not correct the
conditions.
Open, Grounded or Shorted Armature-Test. Use test lamp to check for opens or grounds in
armature. Use Milli-voltmeter and feelers to check for shorted coils.
Remedy-Replace the armature if trouble cannot be repaired.
Lack of Lubrication-Test. Motor armature will not turn freely. Examine bearings and oil
wick.
Remedy-Lubricate the bearings. Do not lubricate excessively.
Dirty, Oily, or Rough Commutator-Test. Examine commutator.
Remedy-If the commutator is greasy and gummy, clean with a fine grade of sandpaper.
Never use emery cloth.
Weak Brush Spring Tension-Test. If horn does not give an even tone or draws very little
current check the brush spring tension.
Remedy-If brush is stuck in holder free up the brush action and increase the spring tension
Open, Shorted, or Grounded Condenser-Test. If there is excessive arcing at the contact
points disconnect one condenser lead and connect a new condenser across the contact
points. If the condenser is shorted the contacts will be held together instead of vibrating.
Remedy-Replace the condenser.
Open Circuit in Horn-Test. Connect an ammeter in the circuit and if no discharge is shown
when the contacts are closed the horn is open circuited.
Remedy-Repair or replace field coil in case the trouble is in that part.
Grounded Circuit in Horn-Test. Disconnect leads and touch one test lamp lead to terminal
of the horn and the other to grounded part of horn and if lamp lights the horn is grounded.
Remedy-Re-insulate or replace the grounded parts.
Contact Points Stick-Test. Remove the cover and observe the action of the contacts with
the engine running and after the engine has been stopped.
Remedy-Clean the contact points and observe again.
Contacts Open and Close Intermittently-Test. Observe the relay contacts with the engine
running moderately.
Remedy-Either speed up the engine or hold the contacts together for a moment so that the
generator will be of the same polarity as the battery. Reverse polarity is experienced when
the battery connections have been interchanged. See that the base of the relay has a good
ground connection.
Early or Late Cut-In-Test. Connect voltmeter in generator and relay circuit and note the
cut-in voltage.
Remedy-If the relay contacts close too soon increase the spring tension on the upper
contact. (Refer to cut-out relay test data, Section IV for specified values.)
Poor Connection Thru Contacts-Test. Check the circuit thru the relay contacts and examine
the points for any dirt or foreign matter which may be lodged between the contacts.
Remedy-Clean the contacts by drawing a heavy piece of paper between them and ascertain
if good electrical contact is being made. Align contact points.
Lamps Do Not Burn-Test. Turn on lights that are connected thru tell-tale relay and see if
they burn.
Remedy-If neither signal lamp nor dash lamp burn it is necessary to examine and replace
bad lamps and see that all connections in the circuit are clean and tight.
Open or Grounded Circuit-Test. Use test lamp to check for an open or grounded circuit.
Place the test points across terminals S and B to check the winding for an open circuit.
Close the switch and check all connections in the circuit and test across the terminals of
the switch for open circuit. Locate grounds by going over the entire circuit.
Remedy-Repair all open or grounded connections. Replace the relay if repair is not possible.
Incorrect Use of Lamps-Test. Check the candle power of the lamps used in the circuit. Some
signal lights use one 21 C.P. 12 volt lamp and others use three 21 C.P. 12 volt lamps. Use
of the wrong size lamp will cause undue point burning which will result in poor circuit thru
the relay.
Remedy-Replace all lamps that exceed 21 C.P. Ascertain the number of lamps used for the
particular installation, and if relay is replaced the unit specified should be used.
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