Power Steering Pump

The power steering pump is used to assist the driver to steer the vehicle at low speeds. The is powered by the fan belt, it has a similar design as an oil pump. It uses a rotor with vanes on it inside a cam ring to pump the power steering fluid to the steering rack. The pump has a high pressure hose that goes to the steering rack and a low pressure hose that returns the fluid from the steering rack. The pump has a pressure relief valve to let the fluid return to the reservoir when the car is traveling at high speeds.

The main problems that occur in steering pumps is that the fluid lines break or the seals wear out so the pump loses fluid. The bearings also wear out due to its age or the fan belt is over tightened. Most power steering pump pulleys are bolted on to the pump shaft although some are pressed on. To get a pulley off that has been pressed on the pulley needs to be heated up so that it expands and then pulled off with a puller.

Wheel Alignment

Pre-checks

• Jack the car up or lift it up with the hoist. Check the tie rod ends with the wheels on the hoist, have someone sit in the driver seat and turn the steering wheel from left to right vigorously. If a clicking sound is heard when checking the tie rod ends it means they are worn, It could also be checked visually or by feeling it with your hand
• Check the ball joint, bushes and the wheel bearing by raising the vehicle and pushing the wheel from side to side and up and down. If the wheel has play the faulty parts need to be replaced or repaired.
• The tire pressures should be checked and pumped up to the correct pressure

Setting up 

• Make sure that the turn tables are locked
• If the car was raised on the hoist it should be pushed off and back on to reset the suspension joints
• The hoist should be locked into the first pin to make sure that the car is level 
• Once the car is on the hoist and in place the turn table locks should be removed

The car is now ready for the wheel alignment machine

The only thing that could be adjusted on the car that we were working on was the toe because it is a front wheel drive car. Things like the caster, camber, steering axis inclination, included angle etc. Can generally not be adjusted on a front wheel drive vehicle

Adjusting the toe on the tie rod

ABS

Anti-lock braking system. Abs prevents the wheels from locking so that the vehicle slows down faster and so that the driver can control the vehicle while braking hard. ABS uses wheel speed sensors to calculate how fast the wheels are moving and whether they are locked up. If a wheel does lock up the abs system reduces the pressure going to it until it moves the same speed as the other wheels then the pressure is supplied to it again.

The system can be checked with a scanning tool to see if the wheel speed sensors, the motor and the valves  are all working correctly. If there is a problem with one of the sensors a multimeter or an oscilloscope can be used to check the sensor and the wires connecting it to the ABS controller.

Brake booster

The brake booster uses vacuum from the intake manifold to increase the braking force supplied by the driver. The booster consists of a metal canister with a diaphragm, a valve and a rod that goes through it that connects the brake pedal and the master cylinder. When the engine is started the manifold vacuums creates a vacuum inside the booster on one side of the diaphragm. When the pedal is pressed the valve is opened allowing air at atmospheric pressure to enter the booster that pushes on the diaphragm that is connected to the push rod. The push rod pushes the piston in the master cylinder with the force from the driver and the force from the atmospheric pressure/ vacuum from the engine.

The length of the push rod can be adjusted to reduce the clearance between the piston and the push rod. To find out how much the push rod had to be adjusted we measured the length of it from the surface of the booster to the end of the rod. We measured the inside of the master cylinder from the outside edge to the piston and subtracted the distance from the surface that gets bolted to the booster to the outside edge that goes into the booster. We then took the measurement of the length inside the cylinder and subtracted the length of the rod to fined the clearance and how much adjustment the push rod needed. If the clearance is correct the brakes will be more responsive and it could reduce a vehicles stopping distance. 

Brake pipe replacements

If a brake pipe fails (cracks, thread gets strips, damaged) a new one can be made. To make a brake you will need the pipe itself, a cutter, nuts that have the correct thread and a brake pipe flaring tool. Measure the old pipe and cut a piece of the pipe off that is the same length. Check the old pipe to see what type of flaring you need and flare one side of the new pipe then put the nuts on and flare the other side with the same type of flare as the old pipe. Once the pipe has been flared on both sides with the right flare and the bolts are on you can bend it to the shape of the old pipe.

Single flared are generally used when connecting the brake pipes to the wheel cylinders as they have brass inserts that look like olives. Double flares are used on the other end of the brake lines. The brake pipes are flared as another measure to ensure that the connections don't leak.

Bench testing a master cylinder

Once the master cylinder has been serviced/repaired it needs to be tested. We clamped the master cylinder in the bench vice and connected brake lines that have been blocked off. To check if the cylinder was working and if it was holding pressure we filled the reservoir with brake fluid and bled the cylinder to get all the air out. We bled it by pushing the piston in with the brake connectors loosened then closed them and released the piston. We repeated it until all the air was out of the system. Then we pushed the piston in with the cylinder completely blocked off to see if it will hold pressure. If the piston keeps going in it means that the fluid is leaking past the piston seals which means that the cylinder needs to be dismantled to find the problem. If the piston stays fixed it means that the cylinder is fine, the cylinder should be cleaned with brake cleaner if it is not going to be installed in a vehicle immediately.

Caliper repair and servicing

The brake fluid from the master cylinder pushes the caliper piston into the brake pads that push against the rotor to slow the wheel down. The problems that can cause the piston to malfunction is caused by the pistons  seals that are leaking or the piston can rust onto the cylinder. This is why it is important to replace brake fluid regularly and to use the correct brake fluid.

 We had difficulty removing the piston as it was corroded. When it was removed we discovered that the person/s that removed the piston previously had damaged it (damaged caused by hard metal tools). The marks on the piston made it unusable. We cleaned out the caliper cylinder and found that the cylinder had a hole in it. In this case the caliper cylinder and piston will need to be replaced as they are both unrepairable. If they were not damaged the cylinders inside diameter and the pistons outside diameter should be measured to make sure it fits correctly. The pistons seals and the dust seal will also need to be replaced.

 Measuring the pistons outside diameter

Measuring the caliper cylinder's inside diameter