912 Manual Checking and Adjusting V-Belt Tension

Checking V-Belt Tension


The generator and air blower are driven by a V-belt. The loads created by these two accessory units impose considerable stresses upon the belt at high engine speeds and, especially, during downshifts. For this reason, we recom- mend that the V-belt tension be frequently checked and adjusted when necessary.

Loose V-belt tension results in belt slippage in the pulley causing the engine to run hot.

excessively high V-belt tension leads to belt failure and, possibly, premature wear of the generator bearings.


912_fig_70 When servicing the engine, care should be excercised to keep oil and grease off the V-belt; oily V-belts should be washed in a soap or detergent solution and then thoroughly rinsed in clear water although it is always of advantage in such cases to install a new belt. V-belts contaminated with oil or grease for any length of time are usually no longer serviceable and must be replaced. When correctly adjusted, the V-belt can be deflected by 15-20 mm (5/8 - 3/4 in.) under slight thumb pressure applied midway between both belt pulleys. The belt should not show any signs of wear such as frayed edges or split flanks.

Adjusting V-Belt Tension


New V-belt will stretch after a short time of use so that they no longer have the proper tension after 50 - 100 km (30-60 miles). For this reason it is absolutely necessary to recheck the belt tension of new belts within a short period subsequent to the installation.

Attempts to remove the V-belt by means of a screw- driver, without loosening the generator pulley, will result in damaged V-belt and pulley.
912_fig_71 1. Remove generator pulley retaining nut (36 mm wrench); to lock the pulley in place during this procedure, insert a square-edged screwdriver into the recess in the inner edged of the pulley and brace, it .against the top bolt protruding from the generator hous- ing. ...More
912_fig_72 3. Arrange spacers between pulley halves as needed. The belt tension should be so adjusted, by adding or removing spacers between the two pulley halves, that the belt will yield by about 15-20 mm (5/8 - 3/4in) under light thumb pressure. Removal o|.ipacers increases the belt tension, addition of spacers decreases the tension (see Fig. 72). ...More
Last modified: Mon, 17 Jan 2005


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