Replacing a Generator

In September of 2005, Lis's bug started acting weird. As she described it, the gas warning light (the one on the dash board with a "G" next to it) was stuck on all the time. A week or so later, when the battery died, we discovered that that little light actually means "Generator". Clamping my multimeter onto the generator in various ways led me to conclude that the generator was indeed dead. The brushes were fine and speaking various incantations (mostly unprintable) while sandpapering the commutator didn't make it any better. Time to break out John Muir's book and replace it!

Here's the engine before we did anything. This is a 1969 Beetle with a 12 volt electrical system. The big cylinder thing in the middle of the picture with the two wires coming out and the drive belt heading down toward the floor is the part in question. It looks so easy to get out!

Of course, life isn't easy. With such a tiny place to put an engine, those wiley Volkswagen engineers decided to make use of an already-spinning part (the generator axel) and clamped a fan on the back. See the plate behind the generator in this picture? See that one little bolt holding it in in the upper-right hand corner? The fan is behind that plate, and that bolt has three friends that live on the other corners. Since the plate lies between the fan and the generator, getting the generator out involves removing that plate. Note that the other four corners aren't visible in the picture.

Here you can almost see where two other bolts are attached to the generator plate. The only way to get to all of them is to take the air cleaner (the black thing in the top-left corner of the picture) and the carburator (the mess of bolts, screws, and springs below the air cleaner) out of the car. So that's what we set out to do.

Here's a better shot of what we had to contend with on the carburator side. The blue cylinder on the left is the coil, the red thing with the cool hair on the bottom is the distributer, and the yellow thing in the middle with the hoses coming out of the top and bottom is the fuel filter. The distributer and fuel line definitely had to come off, and we found taking the coil off made it a lot easier to get to a nasty bolt on the front (FRONT) of the carburator. The carburator, you may remember, is the mess of bolts, screws, and springs on the right in this picture.

After an evening of work and discovering my tool supplies were a little lacking, we got the parts off. The air cleaner was easy - it just lifted off. The carburator took a lot of effort to get to the bolts involved and to disconnect all of the hoses and bits of wire it uses. When we were done we poked a rag in the hole left over. Note that you can now see another of the bolts on the generator plate. Also note that the two bottom ones are still hidden. The beginning of the next day was spent lifting the fan housing (that big curved black thing in the back) so we could get to those two bottom ones.

Here's a shot of the generator without its friends hiding it. It looks so easy to remove! Alas, we still had a couple days of work ahead of us.

Here's the box of parts from night one. I didn't mention it before, but we pulled a few giant air hoses off while pulling other parts out. The are easy to pull off and put back, so they only get mentioned here because one of them is in this box. The other two objects are the air cleaner in the middle and the carburator in the upper-right.

As long as the carburator was out I had to get a picture of it from a different angle. What a complex-looking little block of machinery!.

Eventually we got the generator out of the car, and here it is. See that giant fan on the front? That's the part that caused all of the trouble. Note how clean the generator looks too. All of the grease and dust that had been covering it had already been transferred to our hands by this point. Mmmm...

Getting the fan off took a bit of brute force. We attached this wrench to the nut on the pulley on the back of the generator to give us some help. John Muir's book makes it sound like you should have taken the pully off by this time and should clamp some vice-grip pliers on the shaft, but I think this method worked a lot better. On the front of the generator is a GIANT 36mm (36mm!) nut that we had to take off. Sadly, I wasn't smart enough to take a picture of it, probably because we were too busy trying to figure out where to find a socket that was that big. We ended up borrowing an axel socket from Murray's auto part store. They have a great tool loaner program.

Here's the engine compartment with all of the parts removed. I thought it would probably run a lot better without all of that extra weight in there, but Lis didn't like that idea. We decided to put the parts back before driving it around.

Putting the parts back in was a lot easier than taking them out, probably because we knew what to expect by that point. We had also collected all of the required tools by then. Here you can see the generator back in its home. It's so much shinier than the old one! I made Lis promise not to get the new one dirty.

An hour or two later and we had all of the parts back in the car with only one unexpected extra part. Since it was just a washer and went in a rather unaccessible place, we decided to ceremoniously sweep it under a rug. After getting the car put back together, I stepped back (waaaay back), told Lis to start it up, and watched for an explosion of loose pieces. There was no explosion, but the little generator light stayed on. Testing showed that the generator was putting out plenty of juice (17 volts), so we made the obvious conclusion: someplace in all of our testing, cleaning, and fighting with the original generator we managed to blow out the regulator too. Back to the parts store for us.

Luckily, the regulator is really easy to replace - it is just a little box screwed to the side of the car under the back seat. Here is the one we took out of the car. Judging by its design, I think it is likely it was the original regulator in the car. In fact, I think it may be the first regulator to roll off the line back in 1930. Anyway, it certainly looked like it could die any moment and I am not too surprised we broke it. We just hope this wasn't the problem all along... (Don't worry, testing the generator way back in the beginning sure made it look like the generator really was at fault.)

See? The new regulator was easy to put in place. After putting it in we followed the very easy instructions that came with it to polarize the generator (touch a wire to the B+ and D+ (61) posts at the same time for no more than 2 seconds). We then took car-starting positions again: Lis behind the wheel and me watching for flying parts. Lucky for us, everything went well. The light went out, the lights worked again, and the battery evidently charged. Success!