Repair And Fix it

An automatic choke can be located on the carburetor of an engine, or it can be located a short distance from the carburetor and is called a "divorced" or "remote choke." The choke is important in the operation of a gasoline engine because it restricts the flow of air passing into an engine when the engine is cold; it could struggle to start with less gasoline flowing into the engine.

Automatic Choke

The automatic choke is an important part of a gasoline engine, working in tandem with the carburetor to restrict and increase the flow of air flowing into the engine. The automatic choke can be briefly described as a valve that closes to restrict the flow of air when the engine is cold. As the engine heats up, the automatic choke slowly opens the valve to allow more air to flow into the engine and reduce the amount of gasoline passing into the engine. The choke system of an engine, such as that for an automobile, is recognized as part of the transmission system.

Coil

In general, automatic chokes use a bimetallic coil to operate the choke plate valve system for increasing and reducing the amount of air passing into an engine. The bimetallic coil rotates when it is cold to close the choke plate and stop the passage of air that can mix with gasoline; this is to allow a larger amount of gasoline to arrive in the engine as required when the engine is cold. As the engine heats up, a vacuum forms that pulls the bimetallic coil back from the choke releasing the pressure and allowing more air to mix with the gasoline in the engine.

Types

Although the automatic choke system works in much the same way in integral and divorced systems, the remote automatic choke is housed in the engine manifold instead of attached to the carburetor. Remote automatic chokes use a separate choke pull off system, while integral systems use a tiny vacuum system linked to the throttle to operate a piston to open the automatic choke.

Rods

In repairing automatic choke systems the incorrect thickness of carburetor used can result in problems with the rods used to open and close a divorced system either not completely closing or opening the choke system. Where the automatic choke system is not working correctly, such as the vacuum passageway used by integral systems being clogged, the choke system may not allow the engine to start or operate effectively.

Four-wheel drive vehicles receive torque from the engine in all four wheels at the same time. The original concept was to be able to maintain traction to either haul extra weight or drive in tough road conditions, or both. There are two modes of 4-wheel drives. The part-time mode is used for off-road driving or loose road surfaces. The driver is able to switch from 2-wheel drive to 4-wheel drive as needed. Full-time mode is used in all road conditions all of the time.

Differentials

The 4-wheel drive has a differential between the two front wheels and another between the back wheels. During a turn, all wheels are going at different speeds while at the same time, the inside wheels are following a different path than the outside wheels. The differentials allow front, back, left and right wheels to spin at different speeds during a turn by sending the power from the engine to the wheels. The differentials slow the transmissions rotational speed before it hits the wheels. In this manner it behaves as the last gear reduction of the vehicle.

Transfer Case

The transfer case is said to be the component that defines a vehicle as 4-wheel drive. This device splits power between all four axles on the vehicle. The transfer case is used to lock the front and rear axle drive shafts to force the wheels to have the same speed when they are turning. On part-time 4-wheel drive systems, transfer cases have an extra set of gears. These gears give a low range to the vehicle, providing extra torque.

Drive Shaft

Drive shafts enable the transfer case to transmit power from the drive to the front and back axles. The drive shafts are enclosed inside axle housings and transmit the drive to the tires. In part-time 4-wheel drive vehicles the drive is transmitted through the front axle drive only when the driver uses 4-wheel drive.

Locking Hubs

Every vehicles wheels are bolted to a hub. Part-time 4-wheel drive vehicles are equipped with locking hubs that are designed to disconnect front wheels from the front differential when 4-wheel drive is not engaged. The locking hubs also disconnect the front wheels from the drive shaft when a car is in 2-wheel drive.

Electronics

Electronically controlled clutches are used on some 4-wheel drive vehicles. This type of clutch controls torque transfer between the tires in a much more effective manner than older clutch mechanisms. Many 4-wheel drive systems use Anti Lock Brake Systems (ABS). The ABS systems provide brake-traction control when the tires begin to skid.

No matter how large or small, theres no such thing as a synthetic automobile. Whether its bituminous carbon, petroleum products or the amino acids used to produce many of the materials used in construction, a car has enough organic components that it is almost in itself a living organism. Rubber is one of the most versatile and obvious of your cars organic components, and can show up in some surprising places.

Tires

Ask any six-year-old to name something made of rubber on a car and most likely theyll point to those round, black things underneath it. However, your cars rolling stock actually contains far less rubber than you might think it does, about 15 to 20 percent by weight. The rest of the tire is made up of carbon black (an asphalt product), silicon dioxide (sand or glass), silicone and metal reinforcements.

Bushings and Isolators

Bushings are thick cylinders of rubber that surround a few of the crucial bolts in your suspension, most notably the control arm and steering component fixtures. Your vehicles suspension contains dozens of rubber bushings and isolators that keep road vibrations from transmitting through the metal components and into your spine. Soft rubber does the best job of isolating the driver, but bushings that are too soft will allow the suspension to squirm around instead of reacting in a controlled manner. Most racers do away with rubber bushings altogether and replace them with hard, polyurethane inserts.

Grommets and Plugs

Wires passing through the engine firewall, trunk wall or vehicle floor are typically surrounded with some sort of grommet where they pass through. The grommets keep sharp edges on the metal hole from cutting through the wires and causing a short. The National Hot Rod Association (NHRA) technically prohibits any car from using rubber firewall grommets or plugs, as they can burn uncontrollably in the event of an engine fire. However, the rule is rarely enforced since almost all modern production cars use them.

Fluid Lines

Some portion of your cars fuel, cooling, transmission cooler and power steering systems use rubber lines. These rubber lines are generally less than 24 inches long, and allow the engine to rock under torquing forces. Most production cars also use a short length of rubber in the brake lines to allow for suspension movement; even the braided steel lines that racers use are rubber on the inside.

Weatherstripping

Many modern cars use rubber-based weatherstripping to seal the windows, doors and trunk-lid. However, manufacturers have begun moving away from rubber weatherstripping in favor of plastic, urethane or foam-based alternatives.