One of the routine maintenance items that you should perform on your BMW is the
checking and replacement of your accessory drive belts. The belts are driven
off of the crankshaft and power accessories such as the water pump, power
steering pump, alternator and air conditioning compressor. There are typically
two belts on the car - one that powers the air conditioning compressor and
another that powers everything else. Both should be checked periodically (every
3,000 miles, or when you change your oil), and particular attention should be
paid to the main belt. The car can run fine without the air conditioning belt
installed.
Some of the early E30 cars use a standard
v-belt design, and some of the later cars use what is known as a poly-ribbed
belt (having many channels or ribs on the underside of the belt). The
poly-ribbed belt setup utilizes a spring-loaded belt tensioner pulley that
provides the proper tension for the belt at all times, making adjustment
unnecessary. The traditional style v-belts need to be tensioned using standard
types of clamps and tensioners.
When inspecting your belts, the one thing that
you want to look for is cracks (yellow arrow - Figure 1). If you see any cracks
at all, you should replace your belts. The cracks will usually occur on the
inside of the belt (the surface that typically rides on the surface of the
pulley). With the poly-ribbed belts, this is the grooved surface. With the
v-belts, this is the surfaces on the legs of the 'V'.
With the poly-ribbed belts, replacement is a
snap. The tensioners that hold the belt tight can be easily released using a
socket and or 8 mm hex tool. Different tensioners turn different directions, so
you may have to rotate the tensioner clockwise or counter-clockwise depending
upon your particular car. The description of this process is one of those
things that is difficult to describe, but very easy to do. First, pry off the
small plastic cap that covers the tensioner (green arrow
Figure
1). Then, place your tool into the tensioner and try rotating clockwise or
counter-clockwise - will become immediately apparent how the tensioner releases
the belt (
Figure 2
and
Figure
3).
Removal of the two belts is easy - you do not
have to remove the fan. Simply release the tension on the belt from the
tensioner, and then the belt should simply slide off. Release the tension, and
then you should be able to unwind the belt from the engine. The belt should be
able to be maneuvered around and through the fan - you do not need to remove the
fan to swap out any of the belts (
Figure
4).
It is important to note that if your BMW has
air conditioning, you will need to remove this belt first, as it typically
blocks the other belt. Another tip - if the belt is worn, simply snip it with
some large tin cutters and pull it out of the car, after you have released the
tension on it.
Installation of the new belt is easy. Simply
slide on most of the new belt onto the pulleys, release the tension on the
tensioner, and slide the belt onto the tensioner. Check to make sure that the
belt is securely seated in all of the pulleys. Verify that the ribbed portion
of the belt is set against the crankshaft pulley. The proper orientation of the
belt is shown in
Figure
5.
Replace any plastic caps that you may have
removed from the front of the tensioner pulleys. Now, start the car and peek in
at the belts. Verify that they are turning smoothly on all of the
pulleys.
For engines with the older-style v-belts, the
procedure is nearly identical, except for the tensioning. The alternator is
mounted on a bracket that rotates and is used to keep tension on the belt. In
addition, there is a small rack-and-pinion device on this bracket that allows
you to crank up the tension on the belt (
Figure
6). The first step in setting or releasing tension is to release the nut on
the back of the bracket that keeps the whole assembly secure. Do not attempt to
turn the geared bolt without first releasing this nut on the rear - you will
most likely damage the bracket. With the nut released, you can now turn the
geared bolt counter-clockwise, releasing tension on the belt. Belt replacement
is nearly identical to the poly-ribbed belts.
Well, there you have it -
it's really not too difficult at all
I will let you kmow when I get it replaced
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