Introduction: Alternator Replacement - Volkswagen Upright (Type I) Motor
Recently the battery in my 1971 Westy died.... Normally this is no big deal. However, this battery is less than 2 months old. A newer battery should not go dead, as the alternator re-charges the battery as you drive. Obviously this was not happening for me. I got out my trusty volt-meter, and sure enough, the alternator was putting out 0 volts (more on how to check it in a minute). So I called a good friend of mine that has a mini parts-warehouse at his house and he provided me with a new alternator. This is how to swap them.
Note: Disconnect your battery before beginning any of this work.
19mm socket and ratchet
10mm socket and ratchet
8 mm wrench
Note: If any parts are unknown to you, refer back to the photo on this page with the labels on it.
Note: Disconnect your battery before beginning any of this work.
Step 1: Check New Alternator Out
There is a shaft that comes out of the back of the alternator and spins a fan. The fan is what provides the main cooling for the motor. The fan lives inside the giant shroud at the back of the motor. It is fixed onto the alternator shaft with a great amount of torque. It is pretty difficult to remove without an impact driver. If your new alternator does not have a fan on it, you can follow the next few steps, remove your alternator, then have a shop (or yourself) switch the fan from the old alternator to the new. If you are unsure if you have the torque to do it, get professional help. If this fan comes off at speed...... I shudder to think... Anyhow....
I wanted to make sure the new alternator I had was going to work. I made a visual inspection of the fan to make sure it was not damaged.
I put the alternator next to the battery (which I had out of the vehicle) (Interesting side note, someone once told me if you leave a battery on concrete it will discharge. I can't attest to the veracity of that claim, but to be sure I set mine on a rag, on some bricks) that I had removed. I alligator clipped a wire from the body (shroud cover) of the alternator to the negative terminal of the battery because in the vehicle it would be grounded. I clipped the negative lead of my voltmeter to the negative of the battery, and the positive to the B+ terminal on the alternator. I set my voltmeter to the millivolt-DC reading and spun the fan as fast as I could by hand. It registered on the meter. Good enough for me. (When I hooked my meter to the B+ of the dead alternator in the car, it showed 0. Later when I did the by-hand test on it, it went -0.3 then .2 then 0 then -5... not sure what was up with it, but it obviously wasnt working)
Step 2: Removing the Pulley
To begin taking out the alternator, we have to remove the belt that drives it. The pulley on the front of the alternator is actually 2 pieces. Once you pull the nut off the front and take the belt out, the front half of the pulley comes off and there are circular shims inside (see pic). The shims are what allow you to adjust the tension of the belt. Weird, right? Yes, but also wicked smart. When you get it apart you will see that the pulley halves are dished. The belt rides in that groove. As you separate the halves, the belt rides deeper in that groove, and is effectively "looser". As you remove shims, the halves get closer together, pushing the belt further out towards the circumference of the pulley. Nifty!
If you look down at the top of the pulley, you will see a little nib behind it. We're going to use that and a screwdriver to hang up the pulley so it doesn't turn as we loosen the nut. Look for the notch in the back half of the pulley and stick your screw-driver in there a couple of inches. Use the 19mm socket and begin to turn the nut to the left. When the screw driver hits the nib the pulley will not turn, and you can take the nut off.
Once the nut is off, there may be shims right under it (for safekeeping, theyre not actually doing anyting on the outside of the pulley). Take the front of the pulley off and take the shims out and the belt as well.
Step 3: Shroud Bolts
The alternator is held in-place by 4 bolts in the shroud, and a strap that holds it down to the stand that it's on. These are 10mm bolts, and only 1 is readily accessible by a mortal. Go ahead an take it out. There is one below that is right behind the intake manifold. If you're careful you can get that one as well. The other two screws are blocked by other motor parts, so we're going to have to do some more tearing down.
Step 4: Carburetor Removal
One of our bolts is behind the carburetor, and really, it's just all in the way. Let's get it out of the way.
First, lift off the air-cleaner and set it aside. Take a paper towel or a rag and put it in the top of the carb. The last thing we need is something falling in there. Then you will have real problems.
Note that there may be wires hooked up on the left and right of your carb. Make a note of where they are and maybe take a picture of them for reference later. They're for the automatic choke!
On the bottom left of the carb you will see a little barrel connector that has the accellerator cable poking through it. We need to remove it and make absolutely sure we dont lose it. The barrel connector is an 8mm bolt.
At the bottom of the carb are two 13mm nuts that hold the carb in place on top of the intake manifold. There is one right out front, and one that is pretty much impossible to get to with the distributor in the way.
We have to get the distributor out of the way...
Note: Make extra sure that you do not rotate the distributor at all or else your timing will be off. Also, the cap has to go back on the same way it came off.
The distributor cap has two clamps on it. Push down on the top of the clamp and pull it off. Lift off the cap, and move it out of the way.
Now we can take off the distributor nuts!
Note: You do not need to disconnect the fuel line to the carburetor. However, when you get the carburetor off, do not tip it, as it is full of gasoline.
Once you get the nuts off, lift the carburetor up and set it up front. Also lift up the gasket with it and try not to destroy that. you can put the nuts back on the carb so you dont lose them. You need to put a towel into the throat of the intake manifold. Remeber my note about having real trouble? Yea, drop something in the intake manifold and you are going to be really hating life.
Step 5: Strap, Wiring, and Shroud
On the alternator, behind the terminals, you will see a 1/2" metal band. This is a strap that holds the alternator to the stand it's on. Use a 10mm wrench and socket to loosen that up. Loosen it to the point where you can slide the strap all the way forward to the shroud.
Go ahead and loosen any wiring that may be fastened to the shroud as well.
At this point you should be able to rock the alternator towards you. As it begins to pull away from the shroud you will be able to see the fan. You will most likely only be able to get it part-way out before the bottom part of the fan cover hits up against the intake manifold. If that's the case, we have to loosen the shroud, lift it up and then pull the alternator out.
Be careful when lifting the shroud, as your oil cooler is also under there and you dont want to damage it. It may help to have a friend help with this part. Around left and right sides of the shroud is a 10mm nut holding the shroud to the tins below it (see photo). Loosen those, then lift it straight up about 2 inches and the fan should clear the shroud.
Step 6: New Alternator In
Reversing your steps exactly, place the new alternator in position, and lower the shroud. Tighten the shroud bolts, and re-secure any wiring that was on the shroud. Slide the strap towards you, over the stand, and tighten. Replace the 4 alternator shroud bolts.
Replace the distributor and carburetor. Re-wire the automatic choke if necessary. Replace the B+ and light wires on the alternator.
Step 7: Pulley Adjustment
First, hang the belt on the bottom, crankshaft pulley, then put it up and over the alternator shaft. Place the front of the alternator pulley back on (ensuring it's seated properly) and tighten the bolt. Using your index finger, push on the belt. The belt should only deflect 1/2 to 1 inch or so. If it's too loose it wont drive the alternator. If it's too tight, it may snap. If it is too loose, take shims OUT of the middle of the pulley. This will bring the pulley halves in closer and tighten the belt. If the belt is too tight, add shims INTO the middle of the pulley.
Congratulations! You've just replaced your alternator!