205E - Cranking System Testing & Service

Question 1

What is the first component of the cranking system that must be tested?

Answer 1

The battery group.
Isolate the batteries when testing.

205E pg. 2

Question 2

If the hydrometer on a maintenance free battery is dark, what should be done before testing the battery?

Answer 2

Charge the battery at 15-25Amps for 15 minutes.

205E pg. 3

Question 3

How should a surface charge be drawn off a battery?

Answer 3

Carbon pile and draw 300Amps for 15 seconds.

205E pg. 4

Question 4

How should a battery capacity test be performed?

Answer 4

Draw 1/2 rated CCA for 15 seconds. Voltage should not drop below 9.6V at 21 degrees C.

205E pg. 4

Question 5

If the specific gravity readings of the battery’s cells differ by more than ______, the battery must be replaced.

Answer 5

0.050 points

205E pg. 5

Question 6

If a blue haze appears from any cell while loading a battery, what does this indicate?

Answer 6

A shorted cell. Replace the battery.

205E pg. 5

Question 7

When testing cranking motor current draw, what could cause a higher than spec current draw with a slower cranking speed?

Answer 7

• Increased friction in engine (cold temperatures)
• High viscosity oil
• Mechanical binding in engine
• Lack of cranking motor bushing lubrication
• Armature rubbing on pole shoes
• Internal shorts or ground faults

205E pg. 7

Question 8

What is the acceptable voltage drop across the starter solenoid contact disc?

Answer 8

0.2V

205E pg. 8

Question 9

When using a carbon pile to load the starting system cables in a 12V system, what voltage drop is acceptable?

Answer 9

12V system: 0.5V drop max
24V system: 1V drop max

205E pg. 10

Question 10

In a 24V system, what amperage would you load the starting system cables to when checking for a voltage drop in the cable set?

Answer 10

24V System: Load to 250A
12V System: Load to 500A

205E pg. 9

Question 11

If there are two battery locations or if the system has two sets of cables running to the starter, how would the cables be tested for voltage drop?

Answer 11

Each location’s battery cable set must be tested separately.

Current flow is shared equally by each battery cable set.

12V System: Load carbon pile to 250A (instead of 500A). Max 0.5V drop

24V System: Load carbon pile to 125A (instead of 250A). Max 1V drop

205E pg. 10

Question 12

What is the maximum acceptable voltage drop across the starter magnetic switch coil?

Answer 12

Carbon pile set to 100A (60A on 24V system)
Max 0.2V drop

205E pg. 13

Question 13

What is the maximum acceptable voltage drop across the starter magnetic switch conductors?

Answer 13

Carbon pile set to 100A (60A on 24V system)
Max 0.2V drop across each conductor.
Max 0.5V drop across both conductors and coil together.

205E pg. 13

Question 14

Before removing the starter and when checking if the engine is able to freely rotate, how many revolutions should the engine be manually rotated?

Answer 14

At least 2 revolutions.

205E pg. 19

Question 15

With the cranking motor removed, if the ring gear is found to be damaged, what other component is also likely damaged?

Answer 15

Cranking motor pinon gear.

205E pg. 19

Question 16

When bench testing a starter, it is found to have a higher than specified current draw and a slow no-load speed. What could the possible causes be?

Answer 16

• Internal friction (bearings, bent armature, binding)
• Armature winding shorts
• Field or armature shorts to ground

205E pg. 23

Question 17

If the cranking motor draws higher than normal current flow and the armature rotates at higher than normal speed, what is likely the cause?

Answer 17

Shorted field coils.
Cannot be tested with an ohmmeter. Replace coils.

205E pg. 23

Question 18

Why shouldn’t cranking motors be immersed in solvents during cleaning?

Answer 18

Could dissolve the electrical insulation.

205E pg. 24

Question 19

The _______ is an electrical device that prevents cranking motor overheating. It is connected in series with the solenoid relay (magnetic switch) and is a _________ (Normally open/Normally closed) switch.

Answer 19

Over crank protection switch.
Normally closed.

205E pg. 27

Question 20

What causes starter solenoid chatter? (3)

Answer 20

• Low battery
• Higher than normal electrical resistance in the cranking circuit
• Open solenoid hold-in winding

205E pg. 32

Question 21

What can shorted circuits in the armature be located with?

Answer 21

Growler

Question 22

True/False
High current draw and high free-speed could be the result of a shorted armature winding.

Answer 22

False.
Shorted field coils, resulting in less CEMF.

Question 23

True/False
Armature windings should be checked for shorts by using an ohmmeter.

Answer 23

False.
Use a growler.

Question 24

True/False
An ohmmeter has its leads placed on adjacent commutator bars. The ohmmeter should read OL.

Answer 24

False.
Should read a low resistance as each commutator bar is connected to its adjacent bar through the windings.

205C pg. 11