Technical FIXED: Dynamo brushes replaced without removing from engine

[DimitriL]

Hi guys, just wanted to let anyone know that you can replace the brushes of your dynamo while the dynamo is still mounted on the engine.

Previously I had the issue of the dreaded Generator light being on.

I measured the dynamo and everything seemed fine. I noticed that on the voltage regulator the 3 coil was closed. When I lifted that relay, the generator light would go off. I thought, bingo, this is my problem: the voltage regulator (wrong) so I ordered the electronic one.

When I replaced the voltage regulator, I thought everything was fixed because now the generator light was no longer on. (wrong)

Now I started to direct my mind to the dynamo. I wanted to remove it and completely overhaul it. I removed the airfilter cover, removed the air tube, and located the 17mm nut on the fan side. It is so hard to get in there, plus there is quite a distance from the nut to your tool and you can't use your two hands. I tried for hours anyway I could to remove that 17mm fan nut, I just couldn't!!! On Italian sites I read that mechanics are afraid that the bolt would unscrew so they put a lot of threadlocker on it. You could supposedly take a gas torch (if you can get it in there) and heat up the nut (you can't even see, only feel where it is)...

Dissapointed, the next day I tackled this job again, but this time, I decided to just check the brushes, but that was also a pain, because the two threaded rods, as you remove the end nuts that hold the end cap of the dynamo, the rods would fall in as you replace the cap.

Anyways, I was able to remove the end cap with the brushes, and -lo and behold- one brush was almost at the end, and the other one had barely carbon left and the wire was cracked off. (here is where when tested I could still measure something)

I went to a local car part shop and he didn't have brushes, they sent me to an electric shop. They did have some, but slightly smaller 15mm instead of 16mm x 6.5mm, anyway, I did mount them, and now I can really tell that it works awesomely, they readings are now really correct.

Getting the end cap back on was a challenge with the two rods, you have to find a way to keep them sticking out while you put the cap back on and guide them through the 2 holes of the cap. I tried a couple ways, but in the end I used electrical tape and an extended the rod with a tube of same diameter. I also used two nails behind the brush coil springs to extend the spaces between them so it could slide over the bearing and commutator. This worked out all fine. It's tiring standing up all day bent over with both your hands down.

The other thing I noticed while doing this job: When I wanted to get to the 17mm fan nut, I noticed that on the bottom fat metal pipe, the hose wasn't properly fastened and basically the fat hose was halfway over this pipe of the engine shroud! Meaning: engine cooling was never effective!!

Now when I start the car, I can feel the hot air now being blown out from the top grill under the rear window!

So now, I am very glad and proud of myself that I have a strong dynamo and engine is cooling properly! Plus cleaned those sections...

Just my rant, and I hope it helps someone. Cheers :slayer:
I also made a video of this job:

 

[fiat500]

You did well because that isn't an easy job and it's helpful that you explain the process in a video; I did it once and that finished me.:bang: Now I would always remove the dynamo or alternator when changing the brushes because I think it's advisable to change the bearings (or at least check them) and the commutator should be cleaned at the same time.

I also use Loctite on the impeller nut, which is 19mm on the alternator version, and it is not essential to heat it for removal. The challenge for many people is finding a reliable way to hold the pulley end of the generator whilst turning the nut; I made a tool (pictured...also has appropriate rings for the bigger pulley on my van) for this, which has already paid back the small amount of time in making. There is at least one person around here who is made from elastic and can get at that rear nut from above the engine. For the rest of us stiffs it is relatively straightforward to get at using a socket on a long extension bar whilst lying under the car.

The alternator is easier to remove than the dynamo and overhaul is more straightforward too.

 

[DimitriL]

Thank you Peter. My first mistake was first taking off the pulley. At the impeller side, I used a cross wheel wrench where I cut off the opposite of the 17mm, so now I had a T shape, this helped to secure the impeller nut, then I proceeded to put force on the pulley hub, but.... I broke the pulley hub!!! So it went from worse to worse... Luckily I got it fixed. I applied the force from the pulley side because I have more space there for two hands. But maybe your way is good if you can get under the car and have your two hands. But again, this job is a job I never want to do again, it's as if the impeller nut is welded in! Thanks for your reply.

 

[Vitesse]

There is at least one person around here who is made from elastic and can get at that rear nut from above the engine.

That would be me! If I remove the air box cover and remove the big air intake pipe, I can get my head over the top and get an extension bar on a socket and undo the impeller end. I jam the pulley end with a ring spanner against either the engine mount or bodywork. It is a very tight squeeze though but you can see more from above as obviously the air intake is angled upwards. I have nearly become stuck on a few occasions.

 

[DimitriL]

That would be me! If I remove the air box cover and remove the big air intake pipe, I can get my head over the top and get an extension bar on a socket and undo the impeller end. I jam the pulley end with a ring spanner against either the engine mount or bodywork. It is a very tight squeeze though but you can see more from above as obviously the air intake is angled upwards. I have nearly become stuck on a few occasions.

You surely are elastic! You must have taken off the engine bonnet??

 

[Vitesse]

You surely are elastic! You must have taken off the engine bonnet??

Yeah my engine lid has never been secured by the nut at the bottom on the hinge so it’s simple to slide off with no problem in a few seconds. So long as the latch at the top is securing it in place it doesn’t really need the bolt on the hinge.