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Alternator Removal, Disassembly, Testing And Reinstalling.


Rosssub

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I started the car up this morning after a week parked up to hear a strange whining noise coming from the engine bay. After replacing the AC tensioner pulley bearing last week I thought it might just be a belt:

http://clubsub.org.nz/forum/showthread.php?47099-AC-Idler-Pulley-Tensioner-Pulley-Recon

I popped the bonnet and found my alternator smoking and what seemed like the rear shaft bearing making all the noise.

 

On closer inspection I noticed this:

Subaru_Alternator_003.jpg

 

Subaru_Alternator_002.jpg

 

After 5 minutes of idling from cold the alternator casing was over 100'C. I tested the output voltage at the battery while idling and only had 14.16v, normally it sits at 14.4v-14.6v:

EJ208_Alternator_Removal_003.jpg

 

I then tested the battery voltage with the ignition off and had a normal 12.69v (new battery).

So I've removed the alternator to do some investigating. First disconnecting the negative battery terminal:

EJ208_Alternator_Removal_006.jpg

 

Then remove the accessory belt cover:

EJ208_Alternator_Removal_004.jpg

 

Then remove the loom plug and main battery connection:

EJ208_Alternator_Removal_007.jpg

 

Then loosen off the alternator mounting/pivot bolt:

EJ208_Alternator_Removal_007a.jpg

 

Then loosen the locking bolt and wind the tension adjuster all the way out:

EJ208_Alternator_Removal_008.jpg

 

Now the belt's loose and can be removed:

EJ208_Alternator_Removal_010.jpg

 

Then remove the tension adjuster bolt assembly completely:

EJ208_Alternator_Removal_012.jpg

 

Then remove the pivot bolt:

EJ208_Alternator_Removal_014.jpg

 

The alternator can then be lifted out:

EJ208_Alternator_Removal_015.jpg

 

This is what's hiding underneath for those that haven't seen it yet:

EJ208_Alternator_Removal_016.jpg

 

Tomorrow I'll be disassembling the alternator and checking the front and rear shaft bearings. Then testing continuity and resistance through the rotor assembly and pickup sliders, brushes etc. So a few more pic's to come:

EJ208_Alternator_Removal_017.jpg

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To disassemble the alternator remove the four through bolts that hold the case halves together:

Alternator_Testing_001.jpg

 

Then use a heat gun to warm the centre of the rear casing to 50'C, this is so that the rear shaft bearing will come out of the casing easily:

Alternator_Testing_003.jpg

 

Then use a flat head screwdriver and some force to pry the front casing away:

Alternator_Testing_006.jpg

 

Alternator_Testing_007.jpg

 

Alternator_Testing_008.jpg

 

My rear bearing is completely gone. Dry, loose and rattling when spun:

Alternator_Testing_010.jpg

 

I've soaked the front pulley nut in breakaway. From here I could lock the rotor assembly in a vice with a block of wood either side, then crack the nut and remove the pulley to get at the front bearing. But my vice isn't big enough to hold it. I want to add bearing replacement to this thread so I'll find one I can use:

Alternator_Testing_011.jpg

 

With a multi meter set to ohms, I've checked the resistance between both brush slider rings. This should show approximately 1.8-2.2ohms. Mine is showing 2.7ohms, so out of spec and the rotor assembly needs replacing:

Alternator_Testing_012.jpg

 

I then checked resistance between the slider rings and the main rotor core/shaft. This should show more than 1ohm. Mine is showing 0 or open circuit, so the rotor coil is grounding when it shouldn't be. Again this means the rotor assembly needs replacing:

Alternator_Testing_014.jpg

 

This pic shows the two pick up brushes inside the rear casing:

Alternator_Testing_015.jpg

 

To reassemble everything there's an access hole in the rear casing. For inserting a 0.8mm piece of wire in to hold the spring loaded brushes out of the way:

Alternator_Testing_016.jpg

 

I used a bent piece of wire to press the bushes back into their housing. Then inserted the 0.8mm wire through the access hole to hold the brushes back:

Alternator_Testing_017.jpg

 

Now if everything tested ok and bearing's were fine the rotor assembly can slide back into the rear housing:

Alternator_Testing_018.jpg

 

When I find a decent sized vice I'll throw some more pic's up covering bearing replacement. But either way I know this alternator is toasted.

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  • 2 weeks later...

Found a bigger vice today so took some more pics, carrying on from here:

Alternator_Testing_011.jpg

 

Rotor locked in the vice with soft protection on either side:

Jamie_s_Honda_012.jpg

 

Nut and pulley removed:

Jamie_s_Honda_013.jpg

 

A few light taps with a hammer and the shaft/rotor assembly came out:

Jamie_s_Honda_014.jpg

 

Now the front bearing retainer plate is visible:

Jamie_s_Honda_015.jpg

 

Retainer plate removed showing the front bearing:

Alt_Bearings_001.jpg

 

I flipped the front cover over and used a 16mm socket and hammer to press the bearing out:

Alt_Bearings_002.jpg

 

Front bearing isn't too bad, 47mm OD x 17mm ID x 14mm thick:

Alt_Bearings_003.jpg

 

My smallest gear puller is too big to remove the rear bearing without attacking it with a bench grinder. But the rear bearing is 27mm OD x 10mm ID x 11mm thick:

Alt_Bearings_006.jpg

 

I looked at a few GC8 alternators with the 3 pin loom plug but they were only 80A, so I've brought another BE/BH 100A alternator that's on its way. Looks like the 3.0R Legacy's also run a 100A alternator with a 6 rib pulley/belt, but guessing the pulleys would swap over.

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The replacement alternator arrived yesterday. But it's an 80A Version 5/6 unit p/n 23700AA380, looks to be the same as a version 7 80A unit with p/n 23700AA420. The BH5 runs a 100A p/n 23700AA330. Higher amperage due to the extra electrics (HID lights, electric seats etc). The BP5 runs a 110A p/n 23700AA520/23700AA521 so would be a slight upgrade over my original. All running the same 3 pin loom plug (com/sense/lamp).

ALT_wiring.jpg

 

Thought I'd throw a few pics up showing the difference between the two I have here:

BH5 100A on left (Hitachi unit)- V5/6 GC8 80A on right (Mitsubishi Electric unit):

GC8_V5_6_Alternator_001.jpg

 

BH5 left (Hitachi) - V5/6 GC8 right (Mitsubishi):

GC8_V5_6_Alternator_002.jpg

 

V5/6 (Mitsubishi) left - BH5 (Hitachi) right:

GC8_V5_6_Alternator_003.jpg

 

If the seller doesn't have a BH5 one spare to swap over I'll disassemble, clean and paint the GC8 unit to run for now.

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  • 2 weeks later...

I've returned the 80A alternator that turned up and brought a 100A unit from a 99 RS30 B4 (BEE/EZ30), part number 23700AA401. This runs the 6 rib pulley/belt so I'll disassemble it tomorrow, check it over and fit my original BH5 5 rib pulley:

EZ30_B4_Alternator_002.jpg

 

Cleaned up with a bit of CRC and elbow grease:

EZ30_B4_Alternator_009.jpg

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Pulled the EZ30 alternator apart today. This one came apart by hand once the 4 through bolts were removed:

EZ30_Alternator_New_bearings_001.jpg

 

Here's a look at the Mitsubishi brushes and internal regulator setup:

EZ30_Alternator_New_bearings_002.jpg

 

Rotor assembly in the vice, 24mm nut and 6 rib pulley removed exposing the Mitsubishi front bearing retainer plate screws through the front cover:

EZ30_Alternator_New_bearings_004.jpg

 

Front cover with rotor assembly removed showing the front bearing:

EZ30_Alternator_New_bearings_006.jpg

 

I took the rotor assembly into my local Auto Electricians and got them to remove the rear bearing, then brought replacement bearings off them. The front bearing is identical (Hitachi/Mitsubishi), but the Mitsubishi rear bearing is slightly different 23mm OD x 8mm ID x 14mm thick:

EZ30_Alternator_New_bearings_007.jpg

 

With the four front bearing retainer plate screws removed and the plate off, I used a 16mm socket and hammer to press the old front bearing out:

EZ30_Alternator_New_bearings_011.jpg

 

Then used a 32mm socket to tap the new bearing in. Refitted the retainer plate, then slid the front cover back onto the rotor assembly:

EZ30_Alternator_New_bearings_013.jpg

 

With my original 5 rib Hitachi/BH5 pulley reinstalled, the pulley was rubbing on the front cover. This pic shows the rear difference in the two pulley types. 6 rib Mitsubishi/5 rib Hitachi:

EZ30_Alternator_New_bearings_015.jpg

 

So I've used two Toyota gear box drain plug washers behind the Hitachi pulley to space it out so it clears the Mitsubishi alternator front cover:

EZ30_Alternator_New_bearings_016.jpg

 

Hitachi 5 rib pulley on a Mitsubishi EZ30 alternator with a new front bearing:

EZ30_Alternator_New_bearings_019.jpg

 

With it flipped over I used a 7mm socket/hammer to press the new rear bearing onto the rotor shaft:

EZ30_Alternator_New_bearings_021.jpg

 

Then use the 0.8mm wire through the rear casing access hole to hold the brushes back:

EZ30_Alternator_New_bearings_022.jpg

 

Brushes held back for reassembly:

EZ30_Alternator_New_bearings_023.jpg

 

Then the main case halves/rotor assembly can slide back together:

EZ30_Alternator_New_bearings_025.jpg

 

EZ30_Alternator_New_bearings_026.jpg

 

Then with the four main through bolts reinstalled the piece of wire can be removed, releasing the brushes:

EZ30_Alternator_New_bearings_029.jpg

 

Rebuilt EZ30 100A/5 rib alternator reinstalled in the reverse order of removal:

EZ30_Alternator_New_bearings_033.jpg

 

With the new alternators main cable connection being on an angle, I've removed the red boot and bent the cable's crimped end with pliers:

EZ30_Alternator_New_bearings_035.jpg

 

Loom plug and positive cable reinstalled:

EZ30_Alternator_New_bearings_037.jpg

 

With the negative battery terminal back on and the engine running at cold idle, I have a good 14.6V. Dropping to 14.4V at normal operating temp:

EZ30_Alternator_New_bearings_043.jpg

 

Belt cover reinstalled and all done. RS30 B4 100A Mitsubishi alternator running a BH5 100A Hitachi 5 rib pulley with new bearings:

EZ30_Alternator_New_bearings_042.jpg

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  • 4 years later...

"I then checked resistance between the slider rings and the main rotor core/shaft. This should show more than 1ohm. Mine is showing 0 or open circuit, so the rotor coil is grounding when it shouldn't be. Again this means the rotor assembly needs replacing: "...

 

Open circuit is what it should be.. That means it isn't shorted...

 

Also, the washers you used to pack the pulley out.. They need to be hard, not copper or aluminum. The pulley is only transmitting torque to the shaft by the friction between the pulley and the step or spacer on the shaft.. you can buy steel shims from an engineering supply place.

 

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