Do-it-yourself replacement of timing belt tension rollers

Any friction pairs in a car require periodic replacement, therefore they are considered consumable (non-repairable) parts. The battery only starts the internal combustion engine, after which the generator begins to generate electricity for the on-board system and recharging the battery.

Rice. 1 Replacing the generator belt tension system roller

Therefore, the level of battery recharging depends on the quality of the belt tensioner, which transmits speed to the generator shaft, that is, whether the car will start after stopping the engine next time. The main “consumable” – the generator belt tensioner roller – can be replaced by the car owner on his own if he knows where it is located and what parts need to be removed before doing so.

Purpose of the roller in the generator belt tensioner assembly

Initially, the problem of tensioning the alternator belt in a car was solved by two mounting holes in the body of the electrical device itself. With the advent of air conditioners and other additional devices, it became no longer profitable to put several pulleys on an internal combustion engine shaft to provide individual V-belt transmission to each of them.

Currently, a common V-belt drive is used, and the generator belt tensioner roller as a whole is responsible for the absence of sagging, as in the lower figure.

A single V-belt transmission from the internal combustion engine shaft to several pulleys of auxiliary devices.

Rice. 2 Single V-belt transmission from the internal combustion engine shaft to several pulleys of auxiliary devices

Installation steps

The timing belt is not easy to install; it has its own nuances. Consideration using an 8-valve motor as an example.

The process consists of actions:

Place the product on the rollers.
Install a new tension roller (if necessary), tighten the fastening nut lightly.

Installing the tension roller

Make sure the marks match and adjust if necessary (on the camshaft and crankshaft pulleys).
Correct the mark on the flywheel if it is off. The risk is visible in the hatch on the crankcase; it should be in the center of the cutout in the form of a triangle.
After checking the marks, adjust the belt tension. It is necessary to tighten the roller clockwise not too much, then tighten the fastening nut. To check the tension, the product must be rotated. Good condition: rotated 90 degrees.
Using a 19 key, turn the crankshaft 2 turns. Check where the marks are. If the device is loose, tighten it.
Tighten the nut securing the tensioner pulley. The main thing is not to overdo it, otherwise the pin will bend and the product will slide.

Tension roller stud

Install the crankshaft pulley and tighten it.

Crankshaft pulley

Install the protective cover for the timing mechanism.
Return the alternator belt to its place. Check for damage and replace if necessary.
Adjust the tension of the generator belt.
Screw on the mudguard.
Install the wheel.
Make sure that the engine is working correctly; if not, check the marks.

Attention! When replacing a part with your own hands, it is worth considering that with the belt removed on 1.1 and 1.3 liter engines, you cannot turn the camshaft and crankshaft, there is a risk of valves and pistons meeting.

Some engine modifications do not have a mark on the oil pump cover. It is necessary to make a protrusion on the small crankshaft pulley in the center of the cut.

Tensioner pulley design

Thus, on most modern cars the roller is of the following design:

ball bearing inside
plastic cover with a working surface for the belt on top
landing sleeve inside the roller

Rice. 3 Tensioner pulley design

There are eccentric rollers, the adjustment of which is carried out by shifting the axis relative to the mounting bolt, and conventional ones. In the second option, the roller is mounted motionlessly on the tensioner bracket, and for adjustments the bracket itself is shifted relative to the internal combustion engine shaft.

Rice. 4 Eccentric tensioner pulley

Some cars use self-adjusting spring brackets, in which the number of turns and the diameter of the spring wire are designed for a specific force at the factory.

Rice. 5 Self-adjusting spring tensioner using the example of a Mercedes Sprinter

Since there is a bearing inside the structure, the roller is replaced when any of these parts (bearing race or plastic lining) wears out. In addition, when replacing a belt, it is also recommended to install a new roller/bearing set on the tensioner.

With the increasing popularity of high-quality car audio, owners are installing powerful stereo systems, subwoofers, and several amplifiers in their salons. The on-board network cannot cope with this amount of energy consumption, so a second battery is added.

An example of the layout of two generators with one tensioner pulley for high-quality car audio

Rice. 6 An example of the layout of two generators with one tensioner pulley for high-quality car audio

To ensure its recharging, the best option is to duplicate the generator, for which a second pulley is mounted on the crankshaft of the internal combustion engine. In this case, you have to service two rollers and a belt of the tension system.

Replacing the roller yourself

In contrast to a V-belt timing drive, replacing a car's alternator belt roller is much simpler. Therefore, if you follow the recommendations below, the car owner will be able to perform the operations on his own, after first making sure that the cause of the malfunction really lies in the wear of this consumable.

Diagnostics

Malfunctions of the tensioner installed on the generator belt drive are diagnosed in 90% of cases by a characteristic sound resembling a whistle. However, the tension may weaken, not only from the wear-out of the roller, but also for other reasons:

misalignment - in the absence of alignment of the shafts and pulleys of the belt drive, accordingly, the sound arises due to poor contact of the belt in the cross section, one edge wears out intensively, the other remains intact
ingress of lubricant - in the absence of tightness, oil can get onto the belt, sharply reducing friction, leading to slipping and destruction of the rubber, it is recommended to remove the consumable part, wipe it or replace it entirely, eliminating the cause of the oil leak
hard belt - usually whistles when starting, then heats up, the sound disappears, this is caused by an increase in loads on the pulleys
bearing wear - the whistle is slightly different in tone, the cause is the wear of the race, the bearing is removed for replacement
belt sagging - no need to change anything, tensioner needs to be adjusted
lack of battery recharging - determined by the instruments on the panel

In other cases, the whistling can be eliminated by removing the roller and replacing it with a new consumable. The shine on the working surface of the belt indicates its frequent slipping, the cord peels off from the oil, but cracks on it under normal belt tension are much more difficult to notice.

Dismantling

Before changing the alternator belt tensioner roller, it is necessary to loosen the V-belt drive:

the tension roller adjusting bolt is loosened until the belt can be removed
together with it, 2–3 nuts of the tension bar are loosened (usually 10 and 13)

Attention: Depending on the layout of components/assemblies under the hood of a particular car model/brand, in order to provide access to the tensioner and roller, accordingly, some components and parts will have to be dismantled.

Rice. 7 Removing the roller

For example, on a ZAZ SENS you need to remove the belt that drives the air conditioning compressor shaft. You won’t have to remove anything for Chevy/Niva and Lada Granta.

Belt tension roller - replacement algorithm

Metal roller

Rubber belts are used to ensure the functionality of the generator, water pump, power steering and other vehicle devices.

The number and names of additional equipment depend on the specific brand and model, but in all cases a belt tensioner is used to ensure stable drive.

A pulley is installed on the crankshaft; the number of grooves depends on the number of units driven; the tension roller is also selected taking into account the parameters of the drive pulley.

Understanding the design of rollers will not be difficult even for inexperienced car enthusiasts; it consists of a closed-type rolling bearing (roller or ball), a housing and a fixing bolt.

Plastic tension roller

Tension can be performed either by a built-in eccentric or using a movable bracket.

Replacing the tension roller is rarely done; in the vast majority of cases, this unit operates without problems throughout the entire period of operation of the vehicle.

You can carry out the work yourself or contact a service station.

A malfunction of the roller is indicated by sharp, uncharacteristic sounds under the hood of the car.

Such sounds can also appear due to weakening of the belt tension, but they have a different nature.

Roller bearing

Immediately after starting, the generator produces the maximum amount of electrical energy, the force on the belt increases, and due to poor tension it begins to slip.

As soon as the battery recovers a little, the load on the generator and, accordingly, the belt is significantly reduced; the existing belt tension is sufficient to rotate the pulley without slipping.

How to replace the tension roller

Before starting work, you must find out the exact cause of the sounds that appear. In a weakened state, the belt tension roller should rotate easily; lateral wobbles are not allowed.

The replacement process occurs according to the following algorithm:

Loosen the fastening bolt and check the functionality of the roller. If malfunctions are found, you should completely unscrew the mount and remove the roller.
Clean the outer surfaces of the new roller, paying special attention to the grooves. They must be clean; no grease residues are allowed in the grooves.
Place the new roller in place and lightly secure its position.
Tension the belt with the required force; tension parameters are indicated in the vehicle operating instructions. Tighten the roller bolt securely.

Tension roller location

Depending on the roller design, replacement operations may vary slightly.

Insufficient personal knowledge - consult more experienced drivers or contact a service station.

If you wish, you can change only the bearing, in which case the repair will cost much less than completely replacing the tension roller. The cost of the bearing is an order of magnitude lower than the entire assembled structure.

In most models, the bearings are seated in the housing with slight tension (pressed). They need to be pressed out or carefully knocked out.

Removing the belt

In this case, the loads should be evenly distributed around the circumference of the outer ring and distortions should not be allowed.

Otherwise, there is a risk of cracks appearing on the roller and a complete replacement will be required. Professional mechanics strongly do not recommend replacing roller bearings with ball bearings.

The fact is that designers select the type of bearing depending on the load and number of revolutions. Different types of rolling bearings have large differences in technical characteristics.

When replacing, remember the order of removal operations; installation is performed in the reverse order.