Volkswagen Air Cooled 1949-1969 Repair Guide




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Fig. Fig. 1 There are typically 3 types of accessory drive belts found on vehicles today

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Fig. Fig. 2 An example of a healthy drive belt

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Fig. Fig. 3 Deep cracks in this belt will cause flex, building up heat that will eventually lead to belt failure

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Fig. Fig. 4 The cover of this belt is worn, exposing the critical reinforcing cords to excessive wear

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Fig. Fig. 5 Installing too wide a belt can result in serious belt wear and/or breakage

Inspect the belts for signs of glazing or cracking. A glazed belt will be perfectly smooth from slippage, while a good belt will have a slight texture of fabric visible. Cracks will usually start at the inner edge of the belt and run outward. All worn or damaged drive belts should be replaced immediately. It is best to replace all drive belts at one time, as a preventive maintenance measure, during this service operation.


Generator/Drive Belt

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Fig. Fig. 6 Check the tension of the drive belt with your thumb, as shown

Improper fan belt adjustment can lead to either overheating of the engine or to loss in generating power, or both. In the Type 1 or Type 2 a loose fan belt can cause both, while the slipping of the generator or alternator belt of the Type 3 engine will cause loss of generator efficiency only. In any case, it is important that the fan belt adjustment be checked and, if necessary, corrected at periodic intervals. When adjusted properly, the belt of any Volkswagen engine should deflect approximately 1 / 2 in. when pressed firmly in the center with the thumb. Check the tension at 6,000 mile intervals.


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Fig. Fig. 7 Adjust the generator drive belt tension by adding or subtracting shims between the two pulley halves

Adjustment of the type 1 and 2 fan belt is made as follows: loosen the fan pulley by unscrewing the nut while at the same time holding the pulley from rotating by using a prytool inserted into the slot cut into the inner half of the generator pulley and supported against the upper generator bolt to cause a counter-torque. Remove the nut from the generator shaft pulley and remove the outer half of the pulley. The spacer washers must then be arranged so as to make the fan belt tension either greater or lower. The greater the number of washers between the pulley halves, the smaller the effective diameter of the pulley, and the less the fan belt tension will be. Conversely, the subtraction of washers from between the pulley halves will lead to a larger effective diameter and to a greater degree of fan belt tension. If it is impossible to achieve proper adjustment with all the washers removed, then the fan belt is excessively stretched, and must be replaced. If it is impossible to adjust a new belt properly by using some combination of the available washers, the belt is the wrong size and must not be used. After the correct number of washers has been applied between the pulley halves, install the outer pulley half and place all surplus washers between the outer pulley half and the pulley nut so that they will be available if needed in a subsequent adjustment. Tighten the pulley nut and recheck the adjustment. If incorrect, add or subtract washers between the pulley halves until the proper amount of deflection is achieved. If the belt is too tight, the generator bearings will be subjected to undue stress and to very early failure. On the other hand, if the belt is too loose, it will slip and cause overheating. Cracked or frayed belts should be replaced. There is no comparison between the cost of a fan belt and that of repairing a badly overheated engine. If it is necessary to replace the belt, remove the three sheet metal screws and the crankshaft pulley cover plate to gain access to the pulley.


Adjustment of the fan belt on the type 3 engine is much the same as that of the upright Volkswagen engines. On the type 3 engine, the fan belt is subject to a great deal less stress because it has no fan to turn. Therefore, a loose adjustment is not quite so critical as on the type 1 and 2 models. However, the 1 / 2 in. deflection should nevertheless be maintained, because a loose fan belt could possibly climb over the pulley and foul the fan. In addition, loose fan belts have a shorter service life. In adjusting the type 3 fan belt, the first step is to remove the cover of the air intake housing. Next, hold the generator pulley with a suitable wrench, and unscrew the retaining nut. (Note: a 27mm and a 21mm wrench will come in handy here. Also, be careful that no adjusting washers fall off the shaft into the air intake housing, for they could be quite difficult to remove.) Loosen the generator strap and push the generator slightly forward. Remove the outer pulley half, sleeve and washers included. Arrange the spacer washers as was described in the type 1 and 2 procedure belt adjustment; i.e., more washers between halves mean a looser belt, and fewer washers mean a tighter belt. Install the outer half of the pulley. Install the unused washers on the outside of the outer pulley half so that the total number of washers on the shaft will remain the same. Fit the nut into place and tighten down the generator strap after pulling the generator back to the rear. Tighten the retaining nut and make sure that the generator belt is parallel to the air intake housing and at least 4mm away from it at all points. Install the housing cover.