Keep in mind that this does not apply directly to DSMs but to modern cars in general. I figured since I haven't contributed much at all to this site I'd type this up for anyone about to do this theirselves.
First of all, a bad alternator will show up during load tests as low voltage & a current output problem. even when the regulater is bypassed & full voltage is applied to the alternator field, charging voltage & current will not be up to specifications.
Alternator removal
Before unbolting the alternator, disconnect the battery to prevent damage to parts if wires are shorted. Most alternators are attached to the front of the engine with two or three bolts. Loosen the bolts & remove the belt. Then remove the alternator.
When removing the wires from the back of the alternator, note their location & wether special insulating washers are used. If you make a mistake in reattaching wires to the alternator, system damage can occur.
Depending on vehicle design, the alternator may come out from the top or bottom of the engine compartment. If it must be removed from the bottom, you may need to remove a splash shield to gain access to the alternator mounting brackets & bolts.
Alternator disassembly
To dissassemble an alternator, first scribe marks on the outside of the housing. This will aid you in reassembly. When clamping the alternator in a vise, be carefull not to damage the housing or bend the fan.
Use the directions in a shop manuel to disassemble the alternator. An Allen wrench may be needed to hold the shaft. Use a puller, if needed, to remove the pulley.
Remove the alternator through-bolts. Tap the drive end frame with a plastic or brass mallet. Slide the end frame from the rotor shaft. As you remove the remaining alternator parts, watch how everything fits together.
tech tip
Depending on the type of repair, you may not need to completely disassemble the alternator. For examble, when replacing worn alternator bearings, you do not have to remove the diodes, built-in regulater, or other unrelated parts.
Keep all your parts organized & clean. If you get grease on the brushes , replace them. Grease or oil will ruin the brushes.
CAUTION!
Do not soak the rotor, stator, diode pack, regulater or other electrical components in solvent. Solvent could ruin these components.
Alternator rotor service
A bad alternator rotor can have a bent shaft, scored slip rings, open windings, or shorted windings. Make sure the rotor is in good condition before assembling the alternator. There are several tests designed to check an alternator rotor.
A rotor winding short-to-ground test measures resistance between the rotor shaft & the windings. The ohmmeter should read infinite resistance to show no short to ground
A rotor winding open circuit test measures the resistance bwtween the two slip rings. The meter should read low resistance(2-4 ohms). This would indicate that the windings are not broken.
A rotor current test checks the windings for internal shorts. Connect a 12-bolt battery & an ammeter to the slip rings. Measure the current & compare it to specifications. Typical rotor current should be 3-6 amps. Replace the aternator rotor if it fails any of these three tests.
Alternator stator service
A bad alternator stator can have shorted or open windings. Inspect the stator windings for signs of burning. An open winding is usually detected using an ohmmeter.
To test a stator for open or grpunded windings, connect an ohmmeter to the stator leads. They should produce a low reading. If the reading is high(infinite),the windings are broken & the stator is defective.
Alternator diode service
Bad alternator diodes reduce alternator output current & voltage, & may also cause voltage ripple that can upset computer system operation. Faulty diodes are a frequent cause for aternator failure. It is important to check the condition of the diodes when rebuilding an alternator.
There are various methods used to test alternator diodes: ohmmeter, testy light, diode tester, and a scope test. The ohmmeter is the most common testing tool used when the alternator is disassembled.
When using an ohmmeter or a test light, the diodes must be unsoldered and isolated from each other. Some special diode testers, however, will check the condition of the diodes with all the diodes still connected to each other.
ohmmeter test of diodes
To use an ohmmeter to test the diodes, connect the meter to each diode in one direction and then the other. The meter should read high resistance in one direction and low resistance in the other . This will show you that the diode is functioning as an "electrical check valve". The test should be performed on each diode.
A bad diode can either be shorted or opened. An open diode will have a high resistance in both directions. A shorted diode will have a low resistance in both directions. In either case, the diode must be replaced.
If diodes were unsoldered for testing, they must be resoldered during installation. After pressing in the new diode or obtaining a new diode pack, use a soldering gun and rosin-core solder to attach the diodes leads. Heat the wires quickly to avoid overheating the diodes. Excess heat can ruin a diode.
Alternator bearing service
Worn alternator bearings or dry alternator bearings produce a rumbling or grinding noise during operation. They can become loose enough to upset alternator output by allowing too much rotor shaft movement. When rebuilding an alternator, it is common practice to replace the bearings.
The front alternator bearing, also called the drive end bearing, is usually held in place with a cover plate and small screws. To replace the bearing, remove the screws and plate and lift out the old bearing.
The rear alternator bearing, also referred to as the diode end bearing or slip ring end bearing, is normally pressed into the rear end housing. It may be pressed or carefully driven out of the alternator housing for replacement.
If the bearings are relatively new and you do not replace them, make sure you put a moderate amount of grease into the rear bearing. the front bearing is usually sealed and cannot be greased.
To check the action of the front bearing, rotate it with your finger while feeling for roughness or dryness. Replace the bearing if there is any sign of failure.
Alternator brush service
Worn brushes can affect the output voltage and current of an alternator. As the brushes wear, spring tension and brush pressure on the slip rings will be reduced.
Inspect the brushes and measure their lenth. When the brushes are worned beyond specifications or soaked with oil or grease, replace them. Many technicians simply replace the brushes whenever the alternator is disassembled.
Alternator assembly
After you have inspected and tested the components of an alternator, your ready for reassembly. Alternator construction varies; refer to a service manuel describing a DSM. In general, assemble the alternator in the reverse order of disassembly.
The following is a typical alternator assembly. Keep in mind this is a general article & it may not apply to your DSM.
1. Install of the components in the rear end frame: electronic regulater, diode pack, rear bearing, terminals, and nuts.
2. If the brushes are not mounted on the outside rear of the end frame, you may need to use a piece of stiff wire or a small Allen wrench to install the brushes. Push the brush spring and brush into place. Then, slide your wire or Allen wrench into a hole in the rear end frame. Slide the wire the rest of the way through the hole. The wire of Allen wrench will hold the brushes out of the way as you slide the rotor into the housing.
3. Fit the front end frame into poisition and check the alignment pins or marks. Install and tighten the through-bolts.
4. Pull out the piece of wire or Allen wrench. You should hear the brushes click into place on the slip rings.
5. Install any spacer, the fan, front pulley, lock washer, and nut. Torque the pulley nut to specifications. Then, spin the rotor shaft and pulley to check for free movement. The rotor should spin freely without making unusual noises.
Test alternator output on a bench tester if you got one. In not, test the charging system output after alternator installation.
Alternator installation
With the battery still disconnected, fit the alternator onto the front of the engine. If needed, install the wires on the back of the alternator first. Hand start the bolts and screw them without tighting.
Check the condition of the alternator belt. Replace it if needed. Slip the belt over the engine and alternator pulley. Make sure the belt is aligned properly on each pulley. Adjust belt tension and tighten the bolts. Reconnect the battery.
So there ya go. Teh basics of alternator service. You still awake?
Anyways, sorry if this doesn't belong here or anything. Oh, & if Im incorrect on anything, please hit me up with a pm & I'll correct it.
First of all, a bad alternator will show up during load tests as low voltage & a current output problem. even when the regulater is bypassed & full voltage is applied to the alternator field, charging voltage & current will not be up to specifications.
Alternator removal
Before unbolting the alternator, disconnect the battery to prevent damage to parts if wires are shorted. Most alternators are attached to the front of the engine with two or three bolts. Loosen the bolts & remove the belt. Then remove the alternator.
When removing the wires from the back of the alternator, note their location & wether special insulating washers are used. If you make a mistake in reattaching wires to the alternator, system damage can occur.
Depending on vehicle design, the alternator may come out from the top or bottom of the engine compartment. If it must be removed from the bottom, you may need to remove a splash shield to gain access to the alternator mounting brackets & bolts.
Alternator disassembly
To dissassemble an alternator, first scribe marks on the outside of the housing. This will aid you in reassembly. When clamping the alternator in a vise, be carefull not to damage the housing or bend the fan.
Use the directions in a shop manuel to disassemble the alternator. An Allen wrench may be needed to hold the shaft. Use a puller, if needed, to remove the pulley.
Remove the alternator through-bolts. Tap the drive end frame with a plastic or brass mallet. Slide the end frame from the rotor shaft. As you remove the remaining alternator parts, watch how everything fits together.
tech tip
Depending on the type of repair, you may not need to completely disassemble the alternator. For examble, when replacing worn alternator bearings, you do not have to remove the diodes, built-in regulater, or other unrelated parts.
Keep all your parts organized & clean. If you get grease on the brushes , replace them. Grease or oil will ruin the brushes.
CAUTION!
Do not soak the rotor, stator, diode pack, regulater or other electrical components in solvent. Solvent could ruin these components.
Alternator rotor service
A bad alternator rotor can have a bent shaft, scored slip rings, open windings, or shorted windings. Make sure the rotor is in good condition before assembling the alternator. There are several tests designed to check an alternator rotor.
A rotor winding short-to-ground test measures resistance between the rotor shaft & the windings. The ohmmeter should read infinite resistance to show no short to ground
A rotor winding open circuit test measures the resistance bwtween the two slip rings. The meter should read low resistance(2-4 ohms). This would indicate that the windings are not broken.
A rotor current test checks the windings for internal shorts. Connect a 12-bolt battery & an ammeter to the slip rings. Measure the current & compare it to specifications. Typical rotor current should be 3-6 amps. Replace the aternator rotor if it fails any of these three tests.
Alternator stator service
A bad alternator stator can have shorted or open windings. Inspect the stator windings for signs of burning. An open winding is usually detected using an ohmmeter.
To test a stator for open or grpunded windings, connect an ohmmeter to the stator leads. They should produce a low reading. If the reading is high(infinite),the windings are broken & the stator is defective.
Alternator diode service
Bad alternator diodes reduce alternator output current & voltage, & may also cause voltage ripple that can upset computer system operation. Faulty diodes are a frequent cause for aternator failure. It is important to check the condition of the diodes when rebuilding an alternator.
There are various methods used to test alternator diodes: ohmmeter, testy light, diode tester, and a scope test. The ohmmeter is the most common testing tool used when the alternator is disassembled.
When using an ohmmeter or a test light, the diodes must be unsoldered and isolated from each other. Some special diode testers, however, will check the condition of the diodes with all the diodes still connected to each other.
ohmmeter test of diodes
To use an ohmmeter to test the diodes, connect the meter to each diode in one direction and then the other. The meter should read high resistance in one direction and low resistance in the other . This will show you that the diode is functioning as an "electrical check valve". The test should be performed on each diode.
A bad diode can either be shorted or opened. An open diode will have a high resistance in both directions. A shorted diode will have a low resistance in both directions. In either case, the diode must be replaced.
If diodes were unsoldered for testing, they must be resoldered during installation. After pressing in the new diode or obtaining a new diode pack, use a soldering gun and rosin-core solder to attach the diodes leads. Heat the wires quickly to avoid overheating the diodes. Excess heat can ruin a diode.
Alternator bearing service
Worn alternator bearings or dry alternator bearings produce a rumbling or grinding noise during operation. They can become loose enough to upset alternator output by allowing too much rotor shaft movement. When rebuilding an alternator, it is common practice to replace the bearings.
The front alternator bearing, also called the drive end bearing, is usually held in place with a cover plate and small screws. To replace the bearing, remove the screws and plate and lift out the old bearing.
The rear alternator bearing, also referred to as the diode end bearing or slip ring end bearing, is normally pressed into the rear end housing. It may be pressed or carefully driven out of the alternator housing for replacement.
If the bearings are relatively new and you do not replace them, make sure you put a moderate amount of grease into the rear bearing. the front bearing is usually sealed and cannot be greased.
To check the action of the front bearing, rotate it with your finger while feeling for roughness or dryness. Replace the bearing if there is any sign of failure.
Alternator brush service
Worn brushes can affect the output voltage and current of an alternator. As the brushes wear, spring tension and brush pressure on the slip rings will be reduced.
Inspect the brushes and measure their lenth. When the brushes are worned beyond specifications or soaked with oil or grease, replace them. Many technicians simply replace the brushes whenever the alternator is disassembled.
Alternator assembly
After you have inspected and tested the components of an alternator, your ready for reassembly. Alternator construction varies; refer to a service manuel describing a DSM. In general, assemble the alternator in the reverse order of disassembly.
The following is a typical alternator assembly. Keep in mind this is a general article & it may not apply to your DSM.
1. Install of the components in the rear end frame: electronic regulater, diode pack, rear bearing, terminals, and nuts.
2. If the brushes are not mounted on the outside rear of the end frame, you may need to use a piece of stiff wire or a small Allen wrench to install the brushes. Push the brush spring and brush into place. Then, slide your wire or Allen wrench into a hole in the rear end frame. Slide the wire the rest of the way through the hole. The wire of Allen wrench will hold the brushes out of the way as you slide the rotor into the housing.
3. Fit the front end frame into poisition and check the alignment pins or marks. Install and tighten the through-bolts.
4. Pull out the piece of wire or Allen wrench. You should hear the brushes click into place on the slip rings.
5. Install any spacer, the fan, front pulley, lock washer, and nut. Torque the pulley nut to specifications. Then, spin the rotor shaft and pulley to check for free movement. The rotor should spin freely without making unusual noises.
Test alternator output on a bench tester if you got one. In not, test the charging system output after alternator installation.
Alternator installation
With the battery still disconnected, fit the alternator onto the front of the engine. If needed, install the wires on the back of the alternator first. Hand start the bolts and screw them without tighting.
Check the condition of the alternator belt. Replace it if needed. Slip the belt over the engine and alternator pulley. Make sure the belt is aligned properly on each pulley. Adjust belt tension and tighten the bolts. Reconnect the battery.
So there ya go. Teh basics of alternator service. You still awake?
Anyways, sorry if this doesn't belong here or anything. Oh, & if Im incorrect on anything, please hit me up with a pm & I'll correct it.
