Friday, 17 July 2015

Reasons To Replace Timing Belt

When To Replace Timing Belt

Timing belts have replaced timing chains on many of today's engines. Not to be confused with “V-belts” or “Serpentine belts”, which are located on the outside of the motor to drive accessories, timing belts perform a much more vital role.

The purpose of a timing belt is to provide a connection between the camshaft and crankshaft to ensure that the pistons and valves operate together in proper sequence. Timing belts have proven to be lighter, quieter and more efficient than chains, but those benefits come at a cost - they require more frequent replacement than chains.

Timing belts are used in two types of engines designated as "free-running" and "interference". If the timing belt breaks on a “free-running” design, the engine will stop and you will need a tow to the repair shop. There is enough clearance between the pistons and valves so no mechanical damage usually occurs. The installation of a new belt is usually all that is needed to get you back on the road.

If the timing belt breaks on an “interference engine”, mechanical engine damage will occur. Most commonly, the damage involves the pistons hitting open valves, resulting in the need for expensive repairs. In extreme cases, replacing the engine may be required.
Breakage is not the only reason to replace your timing belt. Looseness and wear can allow the timing belt to slip, resulting in very poor performance, a no-start condition, or engine damage.

Proper maintenance requires timing belt replacement at regular intervals – before it breaks or wears out. The manufacturers provide a replacement schedule and repair information for this critical component.

Odd Smell from Car While Driving

Faulty Hose Composition leads to Smelly Audi A4 Quattro wagon 

Noticed an odd smell from the car, so he stopped at a shop to get it checked out. He was told that the coolant reservoir was cracked and needed to be replaced. Not satisfied with this diagnosis, he later drove to our shop. We performed a pressure test on the reservoir and discovered that the hose between the coolant reservoir and the engine was weeping coolant through the hose material.

If the coolant reservoir appears to be leaking, the technician should also check these possible leak sources before replacing the reservoir.
May be caused by the coolant hose (1) between coolant reservoir and radiator or the coolant hose (2) between coolant reservoir and engine which may have internal cracks (Image 19-A116).
Internal cracks can cause coolant to get inside the coolant hose material and leak from connections to the coolant reservoir (arrows) due to the capillary effect.

The following tools (or equivalents) are required to complete the diagnosis: VAG1274 Cooling System Tester, VAG1274/8 Adapter and VAG1274/9 Adapter.

Applicable Vehicles:
2001 to 2006 All Models, All Engines

Repair Procedure:
(Review safety procedures in the ALLDATA ® system before beginning)

Before replacing coolant reservoir:
Check if coolant hose (1) between coolant reservoir and radiator is leaking at connection to coolant reservoir (Image 19-A116).
Replace that coolant hose if necessary.
Run engine or drive vehicle until coolant reaches a temperature of 80Run engine or drive vehicle until coolant reaches a temperature of 80°C (176°F).

Coolant reservoir, checking for Leaks:
Remove filler cap on expansion tank.
Install tester VAG 1274 and adapter VAG 1274/8 shown in diagram (or equivalents) on expansion tank.
Build up a pressure of approx. 1.0 bar with hand pump on tester
If this pressure is not maintained:
a. Trace and repair leaks.
b. Check if any coolant leak around coolant reservoir still exists.

Pressure relief valve in filler cap, checking:
Screw filler cap onto tester with adapter VAG 1274/9shown in diagram (or equivalent).
Install hand pump and build up pressure.
Pressure relief valve should open at 1.4 to 1.6 bar.
Replace filler cap if necessary.

DO NOT replace coolant reservoir if there is no further coolant leak detected around the coolant reservoir.

Dodge Durango Pulsation

2004 Dodge Durango noticed a different kind of pulsation

It only would occur when lightly applied the brakes over 60 mph.

The vehicle may exhibit pulsation or vibration in the brake pedal and/or steering wheel when the brakes are applied. The condition is most noticeable at speed over 50 MPH but can occur at lower speeds. If the customer indicates that the condition is present, perform the Repair Procedure. The procedure involves installing brake pads, resurfacing the rotors and checking rotor runout.

1 Set of Brake Pads, P/N 05139733AA, will be required to complete the repair.
Applicable Vehicles: 2004-2005 Durango (HB)

Repair Procedure:
(Review safety procedures in the® before beginning)

1. Inspect the front brakes for any signs of abnormal wear or damage. Repair as necessary.

2. Resurface the front brake rotors with a Chrysler® approved on-car brake lathe. If an on-car lathe is not available, the rotor resurfacing must be sublet to a facility with an approved on-car lathe.

3. Remove the calipers.

4. Clean the caliper adapter.

5. Replace the front pads and anti-rattle springs with P/N 05139133AA.

6. Mark one wheel stud on each side with a dab of paint or suitable marker.
NOTE: Wheel stud torque is critical to the success of the repair. The following procedure is intended to identify excessive rotor distortion which could be caused by improper wheel stud torque.

7. Install the wheel and assembly to the hub. Pre-tighten the lug nuts in a cross pattern to 100 Nm (75 ft.lbs.) then final tighten the lug nuts in a cross pattern to:
200 Nm (145 ft.lbs.) for steel wheels or 175 Nm (130 ft.lbs.) for aluminum wheels. Mark the wheel at the same location as the marked wheel stud.

8. Set up a dial indicator to measure mounted rotor runout. Place the dial indicator plunger against the inner machined rotor face, visible between the brake caliper and the front splash shield (Fig. 1). Rotate the wheel and tire assembly two turns and take runout measurement. If the measurement is less than .025 mm (.001 in.) no further action is required. If the measurement is greater than .025 mm (.001 in.) remove the lug nuts and relocate the wheel one stud clockwise, tighten the lug nuts as described in step 7 and check the runout again. Do not remove any brake parts. Repeat step 8 for each wheel location until you achieve the lowest mounted runout. Minimum mounted rotor runout will be achieved by moving the wheel, not the rotor.