• 2017

Fixing a Driving Force


Accessory components, such as power steering, air conditioning, power generation and engine cooling, are driven by a single and/or serpentine drive belt off the engine. The V-belts of yesterday are gone and have been replaced by flexible flat belts (Figure 1). This illustration shows the serpentine drive belt on a 2.4L engine used in a PT Cruiser.

Belt material has improved significantly over the years, but that does not eliminate the need for service. These belts are wear components and, over time, these parts might require replacement. Depending on the make and model, belt replacement can be a tricky proposition.


Figure1Accessory drive belt technology has evolved from the old V-belt (if you cut the belt and looked at the cross-section, it looked like a V, thus the name V-belt). The accessory drive belts used today are flat belts that have several ribs. These ribs ride in matching grooves on the pulleys of the accessory equipment. Serpentine belts wear out gradually and it can be difficult to spot abnormal wear or damage, especially when you’re looking into a crowded engine compartment. A serpentine belt can look good to the naked eye, but may be close to failure.

Drive belts manufactured before 2000 would clearly show the signs of wear and damage, most notably cracks in the material. That is no longer the case today. Modern drive belts might develop minor cracks across the ribbed side (due to reverse bending), but these minor cracks are considered normal and acceptable. Parallel cracks are not.

Because serpentine drive belts wear out gradually, and belt material has improved significantly over the last 20 years or so, it’s not likely that you’ll be replacing drive belts on your 2014 minivan anytime soon. But, if you have an older minivan with the 3.3L/3.8L V6, or a high-mileage PT Cruiser with the old 2.4L 4-cylinder engine, or similar vehicle, regular belt inspection should be at the top of your maintenance list.

Satisfactory performance of these belts depends on belt condition and proper belt tension. And, detecting wear cannot be done by visual inspection. While belt replacement is required if frayed cords, severe glazing and missing ribs (Figure 2) are seen, excessive wear can only be determined if belt wear is checked. If belt wear is not checked, sufficient material can be lost that can cause performance problems such as belt slippage.

Many technicians, at both FCA US LLC dealers and independent repair shops, use aftermarket gauges to measure belt wear. Gates Corp® developed the New Belt Wear Gauge in 2015 with input from automotive technicians. This simple tool gives a quick pass/fail result on the condition of any ribbed drive belt. This gauge can be used with the belt on or off the vehicle, with one hand and even in places where you can’t see the belt.

Simply press the tool ribs into the belt grooves (Figure 3), using gentle pressure to hold the gauge in place. Try to rock the gauge back and forth. If the gauge remains tight in the belt grooves, it’s still good. If the tool rocks back and forth, replace the belt. It’s worn.


CPT07BL4_020When discussing drive belt service on older vehicles for which this repair is more likely to be performed (10 years or older/100,000+ miles), two of the more common engines in this group are the 2.4L 4-cylinder and 3.3L/3.8L V6 commonly used in the PT Cruiser and the minivans, respectively. Let’s review the drive belt replacement on the PT Cruiser first.

Everyone knows that the engine compartment on the PT Cruiser is crowded and that might be an understatement. To
start this job on this car, raise the vehicle on a hoist, then remove the tire/wheel assembly and the splash shield that protects the lower section of the drive belt.

Using a wrench, rotate the belt tensioner clockwise until the belt can be removed from the power steering pump pulley. Gently, release the spring tension on the tensioner. Remove the belt from the A/C pulley and crankshaft pulleys. Inspect the belt pulley grooves. These pulleys must be free of oil, grease and coolants before installing the new belt.

On this particular engine, the generator is driven by a separate ribbed drive belt. If the serpentine belt is being replaced, the generator belt should be replaced at the same time. After all, in order to remove the generator belt, the serpentine must be removed. Loosen the bottom pivot bolt, then the locking nut. Next, loosen the adjusting bolt to the point where the drive belt can be removed from the generator pulley.

Note: The adjusting bolt can rust over time, especially if the vehicle in which the engine is installed is driven in a temperate or humid climate. If the bolt is rusted, a greater than normal effort might be required to loosen the bolt; replacing the bolt is a good idea.

Install the new generator belt over the crankshaft pulley, then over the generator pulley. Adjust the belt tension by tightening the adjustment bolt. The correct tension can be determined by using Special Tool 8371, Belt Tension Gauge Adapter, and a scan tool. The gauge adapter is used to measure the frequency of the belt tension. When the proper tension is reached, tighten the locking nut and pivot bolt.

Install the new serpentine belt over all the pulleys except the power steering pump pulley. Rotate the belt tensioner clockwise until the belt can be placed on the power steering pump pulley. Slowly release the spring tension onto the belt. The indicator mark on the tensioner should align approximately with the nominal belt length mark. Re-install the splash shield and the job is done.

On an older minivan, there is only one drive belt that drives all the accessory components, which makes the job a little easier. Raise the vehicle on a hoist, then remove the tire/wheel assembly and the drive belt shield. Using a wrench, rotate the tensioner clockwise and remove the belt from each pulley. Gently, release the spring tension on the tensioner.

As was the case with the PT Cruiser, inspect the belt pulley grooves. These pulleys must be free of oil, grease and coolants before installing the new belt.

To install the new serpentine belt, route and position the belt onto all pulleys, except for the crankshaft pulley. Rotate belt tensioner clockwise until belt can be installed onto the crankshaft pulley. Slowly release belt tensioner. Verify that the new belt is properly routed and engaged on all pulleys. Install drive belt shield and lower vehicle.

TAGS:   |   |   |   |   |   |   |   |