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1998 S70 Alternator bearing change

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

This topic is in the MVS Volvo Repair Database » 1998 S70 Alternator Bearing Change DIY
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Volvo Repair Database 1998 S70 Alternator bearing change

Post by Atis »

In this post https://www.matthewsvolvosite.com/forums ... 79#p352979I had a problem with noisy alternator bearings. The symptom was a high pitched noise which was proportional to the engine rpm, but higher. For me it seemed like some plastic is rubbing on another surface. It occurred only when the engine was cold and the car was sitting for some days. Later it occurred at every cold start.

To verify the alternator bearing problem you just have to remove the serpentine belt and rotate the pulley by hand. In my case the noise was not too dramatic but obvious, and in some positions, there was a clearly noticeable radial shaft play.

So to change the bearings you will need a „6203 2RS” , a „6303 2RS” bearing and a plastic „shell” for the rear bearing. I recommend to buy a new slip ring and new brushes (or complete voltage regulator), as if they are worn, you can save the effort of the repeated alternator removal. Four pcs of M4x20 tapered philips head screws are recommended as well, as there is chance that you had to drill them out.
With regards tools you will need:

-Philips head screwdriver small and a bit bigger
-Flathead screwdriver at least 2 pcs as small pry bars
-bearing removal tool, small one (try to get the 2 claws type)
-plunger (I hope it is called like that; the small bar you use to knock out small shafts, rivets or screws)
-a bigger hammer :D (the rubber type)
-vice (the big fat mama type)
-solder (the bigger the better, 100W was sufficient for me)
-sockets: size 8 and 24
-Impact gun
-16 socket for spark plugs (or similar size and long enough tube)
-angle grinder
-fine sand paper (I have used grade1000)
-small needle type file

First of all remove the alternator from the car. I would not like to cover this step in details as there are plenty of good description on how to do that. (I recommend the video of Robert Spinner a.k.a. Rspi)

So here is the removed alternator:
Remove the pulley from the front side with a 24 socket. I used an air impact driver. Even a small 3/8 one did the trick easily. You can try to counterhold on the fans inside, but I do not recommend it as they are really soft and you can easily bend them. Without an impact gun, I will just try a breaker bar and hit it with a big hammer.
The pulley should came off easily from the shaft. Below the pulley there is a spacer on the shaft fitted with tight tolerance, so do not try to pry it off now. You will see four philips head screws, those are holding the bearing plate at the inside of the front housing. Pull those screws out. In my case they were pretty badly rusted in, so I had to drill them out. They are M4x20 screws, so a 4.5 drill will do the job.
Front bearing advice.jpg
On the back side there are 3 small philips head screws, remove them and push the plastic clips inside to remove the plastic cover at the back.
Now you can see the voltage regulator, the slip rings and the diodes. Pull the two philips head screws of the voltage regulator and remove it. Clean the contacts.
You can see the 6 electrical connections with the stationary coils. These are double copper wires crimped together. Pry the crimps out and free the ends of the copper wires. (I am not 100% sure that this step is really needed, but if you would like to avoid demaging the coils, you have to separate the houings and the coils)
If all of the wires are free, you can pull the 3 philips screws of the doide assembly and remove it.

Remove the 4 screws which are holding the aluminum housings together (socket size 8). Pry apart the two aluminum housing parts. There is a pretty big gap between the two parts where you can pry. I did that with a big flathed screwdriver, going around the contour of the gap.
The shaft with the bearings will remain in the front housing. In my case the stationary coils just fall out from the aluminum housing, so be careful not to drop it. Make some marks how the pieces are going together.

To remove the shaft from the front housing, I have inserted a plunger in the pulley end of the shaft (it is hollow) and knocked the plunger with the parts above on a vice (shaft vertically, the plunger is below and I just hit the whole thing onto the vice – I was a bit desperate at this point, so I simply forgot to take pic... see second pic for advice). If you repeat that several times, the front bearing will come out slowly from the housing.

Now you should have the two housings and the shaft assembly apart.
Shaft assembly with front housing
Shaft assembly with front housing
To remove the rear bearing use a bearing removal tool. Be aware that the rear end of the shaft is the slip ring itself, which is plastic. It is hollow and some millimeter deeper there is the actual steel shaft. So to avoid damaging the original slip ring with the bearing removal tool, I have put an M3 nut in the hollow end of the slip ring. It was just enough to have a good point for the removal tool's shaft .
Rear bearing advice.jpg
To remove the front bearing you have to pry off the washer below the pulley first. You can do that with two large flathead screwdriver. Some penetrating oil could be useful here. Note the orientation of the washer (the stepped side towards the bearing).

Now comes the funny part. Grip the front bearing gently in the vice. Place a rag or some kind of towel over the shaft and now let all of your anger, frustration and hate into that bearing by simply crashing it with the vice. Clean off the remaining of the outer ring and the balls. (Obviously be careful not to damage the shaft assembly with this step, so be carefully to grip only the bearing).
To remove the internal ring of the bearing you have grind down that ring until the shaft. I have used a 1mm cutting disc to cut really close to the shaft, and after that grind it further until the shaft was just visible. When you have reached the shaft, you can try to rotate the ring (i. e. punch it with a plunger and hammer). If the material is thick enough near the cut, it will break and then you can pry it off with 2 flathead screwdrivers just enough to place a bearing removal tool below.
(already pried up a bit)
(I used the same tool for the rear bearing)

As the shaft was rusted below the ring, I have used a fine sandpaper to polish it.
Before putting everything back, it is a good time to clean all the parts. I just simply brushed the housings and used some break cleaner for the other parts.

Putting together:

Place the plastic bearing „shell” in the rear housing.
(plastic thingy halfway in)

Place the front bearing in the front housing. You can use a rubber hammer and a large socket (just a bit smaller diameter that the outer ring), but I was able to push that in by hand, pushing with two thumbs repeatedly and going around. Put the bearing plate in place and fix it with the four M4 screws. Be careful with the orientation of the plate, it should touch only the outer ring of the bearing.
Front bearing, cover plate and stationary coils in place.

Place the rear bearing on the slip ring and knock it on place. You can use a long 16 socket for that. I have used the washer from the front side, the old bearing and a socket... jut be careful to hit only the inner ring. You do not have to knock it fully down, just be sure that the connecting surface of the shaft is visible above the bearing.
New rear install.jpg
Clean the wire ends of the coils with sand paper. If they are nice and shiny again, than you can place the coils into the front housing (mind your marks). You could now put the shaft into the front housing. You should be able to push the shaft assembly in the bearing.
If everything is in place you can put the rear housing back in place. I was able to push it down almost totally, but at the end I just put back the 4 screws of the housing and in a cross pattern slowly tightened the screws thus pushing the housings together. Tighten those screws.
Get a small file and clean the crimps of the diode assembly.
Now you can put back the diode assembly. Be careful to lead every wire back to its place. Put the three philips screws back and tighten them.
Fold back the crimps onto the wires. Use a powerful solder to solder the wires back to the crimps. Check that there is a good amount of solder there as there will be some amps in those solder joints.

Put the voltage regulator back in place and tighten it down.
Put back the plastic cover, engage the clips and secure it with the three small philips screws

Clean the inside of the front washer with sandpaper and knock it back on the front side of the shaft with a socket or with a piece of metal tube.
Put back the pulley and the spring washer and tighten it down. There is a special tool for that which fits into the hollow end of the shaft. I did not had that tool, so just used a normal 24 socket+bar. Using weight of the shaft and with a „sudden” tightening it already grabbed the pulley. Then I hold the pulley itself and tightened the nut.
Braves can use impact gun, I was afraid that it will ruin the new bearings.

Some further advice:
Be aware that everything inside the alternator is soft. The shaft and the fan blades can be really easily damaged.
If you would like to change the slip ring as well, you must separate the wires of the rotor and the slip ring. It is a welded connection, so a dremel will be useful there. To get the slip ring off, gently cut the slip ring into pieces and then pull it off from the shaft. The shaft itself below the slip ring is really small in diameter, so be careful not to bend it. If you could get the old slip ring off, you just have to slide the new one on and solder it to the wires. Be aware that it fits only one way on the shaft, and if you mess it up, you will only notice it when it is too late and it can be taken off only by damaging it.

This how the slip ring looks like:
So that's all folks! :)
I hope that it will be useful for someone.

P.S: sorry for the crappy pics, next time I will take my camera with me, not just the cell phone.

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Post by cn90 »


This is what an alternator rebuild should be done! The quality is much better than buying rebuilt alternator from places like Autozone, Advance Auto. Rebuilt alternators used to be good in the 1980s and 1990s. Recently, during the last 10-15 years, there is an influx of Chinese parts and the rebuilders cut corner here and there (sometimes they don't even replace the VR).

In my experience, at 150K, most Bosch alternators slip rings are still good, and probably good to 250K or so. So a little bit of emery cloth to shine them is good enough. Of course you can replace the slip rings too.

Then it is down to:
- New Bosch VR, which includes the brushes as well. About $50.
- Front Bearing: use only quality bearings such as Nachi, Koyo, NTN etc.
- Rear Bearing: use only quality bearings such as Nachi, Koyo, NTN etc.

The bottom line is: for less than $100 and some labor, you will basically have a brand-new alternator, rebuilt the proper way as mentioned by the O.P.

Re: lifespan of components:

1. VR: for some reasons, the VR can go out at 50K or 250K. Being an electronic part that regulates voltage all the time, it may be dead any time. This is the most unpredictable component of an alternator. This is why this part can be purchased online.

2. Diode: this part rarely goes bad, so it is perfectly fine to re-use the diode. There is a reason why this part can rarely be found online, simply b/c there is very little demand for it.

3. Bearing life is about 150K-180K, after that it is a guess work. Best is to replace them if the alternator has more than 150K on it.
2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+

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Post by cn90 »

The trick for the FRONT bearing was nicely demonstrated in the youtube video below.

For the INNER race of the bearing, I don't see the need for the cutting disc. You simply apply the claws of the bearing removal tool into the existing groove of the INNER race and pull.

2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+

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Post by cn90 »

The WHITE plastic ring: where did you buy it from?
2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+

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Post by mecheng »

Nice work!!

So typically to see easy assembly design for the Japanese alternator. Needlessly difficult German design.

I've rarely needed to replace bearings on the alternator, I can usually just oil them in place with Electric Motor Oil (not engine oil which uses detergents). But for the Bosch alternator there is a front sheild I see from the video. The rear bearing looks easy to oil as long as you remove the rear cover.
I bet most rebuilds don't replace the bearing.
1998 Volvo S70 T5 - SE - 240km - Sold July 2018
1997 Volvo 850 GLT - 190km
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Post by Atis »

@ cn90: I got the white plastic ring from a local alternator and starter re builder shop. They are doing repairs and selling parts as well. I kept the original slip ring and brushes because they did not had OEM parts only aftermarket. The whole set was ~20 USD.
You can find these kind of sets in ebay as well.


That video helped me a lot to be honest... :wink:

@mecheng: To pull the inner ring by its race... I did not thought about that... next time I will try it, although I am not sure whether that tool could grab the race itself.

The bearings in these alternators can not be re oiled as they are sealed design. The front bearing in my case had a failed sealing as the grease inside was full of dirt (I think that was the root cause of the failure).

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