STX550 free running pulley on alternator replacement.

[JLA]

I have a spare alternator for my STX550 Navara. The free running pulley fails occasionally so I have been wondering how it all works. this alternator seems different to the others I have looked at.

I am aware of the special tools that are available to replace these pulleys. The pulley has a spline and the axle of the alternator normally has either has a hole through the end with either a spline or hex for tool insertion to stop the shaft turning while the pulley is unscrewed. The problem I have is that the Nissan shaft does have a hole but it is not splined or hex’d.

I am wanting to tool up so I can replace this bearing in-situ on the side of the road. The outer tool is available in many of the eBay kits, but not the inner tool it seems.

Any help appreciated.

 

[JLA]

Putting the question another way: How do I hold the alternator rotor shaft stationary so I can unscrew the pulley with a special tool? Poking a screwdriver inside the alternator to jam it is not a great suggestion, the internal fan is physically weak and the windings are very exposed.

I am tempted to use a rattle gun but wonder if that would cause damage?

Hopefully someone has already tackled this.

 

[landmannnn]

A rattle gun is the usual tool.

 

[BarneyB]

Is the shaft straight or tapered?

 

[Scott52]

I overhauled my alternator last year. I replaced the pulley, bearings and brushes. For interest the cost of bearings and brushes was only a bit over $30.

I used a rattle gun with the splined tool and the pulley came off easily. I couldn't see a hex socket or similar on the other end to help get the pulley off.

If it's not unscrewing, you can split the alternator case first by removing the four long bolts and pull the rear half off. Clamp the stator in a vice and have another go with the rattle gun. Once the pulley's removed you can then pull the front half of the cover off.

However I don't think you'd be doing that on the side of the road.

 

[JLA]

Is the shaft straight or tapered?

Straight.

 

[blackpete]

I had to replace my pulley last year. You definitely need a rattle gun to remove the pulley safely and tool 33 point spline>Make sure you get the right pulley because they look the same but a slightly different offset and diameter. Nissan part number 23151-5X21A.

 

[JLA]

I overhauled my alternator last year. I replaced the pulley, bearings and brushes. For interest the cost of bearings and brushes was only a bit over $30.

I used a rattle gun with the splined tool and the pulley came off easily. I couldn't see a hex socket or similar on the other end to help get the pulley off.

If it's not unscrewing, you can split the alternator case first by removing the four long bolts and pull the rear half off. Clamp the stator in a vice and have another go with the rattle gun. Once the pulley's removed you can then pull the front half of the cover off.

However I don't think you'd be doing that on the side of the road.

I think I will be copying your work. Preventative maintenance is the best approach with this.

 

[JLA]

I had to replace my pulley last year. You definitely need a rattle gun to remove the pulley safely and tool 33 point spline>Make sure you get the right pulley because they look the same but a slightly different offset and diameter. Nissan part number 23151-5X21A.

It seems to be unusual for this type of free wheeling alternator not to have a hex hole in the end of the shaft.

Today Nissan Parts told me they have never sold one of these free wheeling pulleys for an STX550 D40 in Australia, and they are available ex Japan with a 12 week wait. $240.
Bursons were able to order in the part, next day.
The part number that Bursons used to order the free wheeling pulley is CP404, obviously not a Nissan number. $120. That may only fit an STX550.

 

[Scott52]

I think I will be copying your work. Preventative maintenance is the best approach with this.

The OEM brushes were expensive (about $60 a pair from memory) so I used generic brushes . They were OEX Part # BRX72100. 8mm x 5mm x 27mm long. Filed to about 23mm to match OEM. A pair cost $11 from NAPA.

https://www.autopro.com.au/oex-replacement-alternator-br-den-5x8x27-sp127019-brx72100

I reused the springs and clips from the old Nissan brushes. I put the brush fly lead through the spring and clip and pulled the lead through to set the spring at the same compressed length as the OEM then soldered. I drilled holes in the ends for the retaining wire used during installation. They ended up looking like the OEM type below.

It was fun making my own and saving a small fortune by avoiding the Nissan tax system.

 

[Old.Tony]

^ Back when we upgraded our alternator, we were running x 130W halogen driving lights, x40W light bars, 1x 120W light bar and two fridges in the tub plus sending 35A down to the caravan to charge the battery, run the fridge and charge the breakaway battery. This justified the purchase of a 150A alternator.

If that thing fails - which came with a 5yr warranty - my intention is to crack it open and attempt a repair. I did it on my motorcycle out of necessity - I'd replaced the 40A alternator with a 90A unit, and within a few thousand km it died (cracked a wire on the rotor). I soldered it up (using ordinary solder) and it lasted about 20 minutes of running time. I've now soldered it using silversolder, but I had to use a 150W iron to melt that stuff - I don't have anything that gets that hot that's portable so I might attempt a repair on the road. I've got a butane-powered iron, I'll try it and see how it goes, but for my first few trips away I'm taking a spare battery with me!

 

[JLA]

I soldered it up (using ordinary solder) and it lasted about 20 minutes of running time. I've now soldered it using silversolder, but I had to use a 150W iron to melt that stuff

20 years ago I was in the electronics game and had lots of failures with solder joints failing especially where they were supporting a heavy component.
They say lead remains a liquid and keeps flowing although slowly, resulting in a failed solder joint. The tin in solder stiffens it up a bit but not enough to prevent the joint deforming, causing a failure.
In an alternator the forces on the solder joint must have been extreme so no wonder it quickly failed.

I would not have thought of using silver solder but it is much stronger. Unfortunately it has too high a melting point for electronic components but ideal for the alternator windings.

Best of luck fixing that on the roadside.

 

[Scott52]

Quote: "I put the brush fly lead through the spring and clip and pulled the lead through to set the spring at the same compressed length as the OEM then soldered."

I should clarify for anyone who'd be interested in using the generic brushes.

I pulled the lead through the clip and looped and twisted the wire over the post thereby creating a mechanical connection that was supplemented with solder. You can see the post was made during manufacture by punching a slot with the removed piece ending up at right angles to the face of the clip.

The OEM lead appeared to be spot welded to that post so I just snipped it off. My new connection was more robust than the original.

A mechanical connection is required because once the brush assembly is slid into the brush holder the clip is soldered into place ... you need the lead to stay in it's position relative to the clip and not slip through once the solder melts again.

The high definition photo below should give you the idea.

I've done about 15,000km in remote areas since the alternator overhaul without any issues.

Some useful data: The OEM brushes are 18mm long from the wear line. I did the overhaul at 160,000km and had used 10mm so there was still 8mm left. Based on that data, the estimated life is about 288,000km. So anyone with +250,000km will need to start thinking about new brushes.

 

[JLA]

V9X. Nissan say they don’t have any alternator pullies. In fact they say that they have upgraded both the alternator and the pulley. The pulley that they supply now is the new pulley and different to the original pulley.
Nissan do have the new alternator (with pulley) available for $1,790.

I notice navlife also have a drop-in replacement alternator available for about $650 including pulley. Not sure if spare pullies are available for it but I think it would be likely. StackPath

I tried getting the original pulley from various places but could not match it.

 

[Old.Tony]

V9X. Nissan say they don’t have any alternator pullies. In fact they say that they have upgraded both the alternator and the pulley. The pulley that they supply now is the new pulley and different to the original pulley.
Nissan do have the new alternator (with pulley) available for $1,790.

I notice navlife also have a drop-in replacement alternator available for about $650 including pulley. Not sure if spare pullies are available for it but I think it would be likely. StackPath

I tried getting the original pulley from various places but could not match it.

Here's a more palatable alternative:

https://www.ebay.com.au/itm/173854709734
I have an eBay alternator on my car and have no trouble with it.

 

[JLA]

For that price I could buy two!