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Head gaskets serve a major purpose, and without them, or with faulty ones, car engines would run terrible, if at all. These gaskets are specially engineered to withstand extreme heat and compression that is built up within the engine providing an air tight seal. Understanding how head gaskets work is important to proper car maintenance.

Identification

The head gasket is located between the engine block and the head. The head bolts on top of the engine block and the valve cover bolts on top of the head. The head gasket is made of metal and is a one-piece gasket.

Function

The gasket ensures that the compression the engine builds stays within the block and doesnt escape. The gasket also serves to keep any oil from leaking out of the engine, and it provides a separation of oil and coolant within the engine block.

Considerations

To determine if there is a head gasket leak, start the engine, and before it gets too hot, run a hand across the seam where the gasket is to "feel" if any pressure is coming out from the area. There should be zero pressure along the seam. Another way would be to check the coolant to see if it has an oily feel or brownish color to it. If the head gasket is leaking from inside the engine block, it will allow oil and coolant to mix together. Looking at the underside of the oil filler cap to see if it is a milky brownish color could also represent a coolant and oil mix. Another inspection would be to check for oil leaks along the gasket seam area. Degrease the area first, run the engine at a high rpm and inspect for leaks. A mechanic can also perform a test to determine any loss of compression through the gasket area.

Time Frame

There isnt a specific time frame involved regarding the life of a head gasket. The original factory gasket may last the life of the engine, or it may break down earlier. The quality of the gasket and driving habits are factors regarding the life of the gasket. Heavy accelerations, as used when racing for instance, creating extreme pressure within the engine, can weaken the gasket prematurely.

Warning

If the the mix of oil and coolant is discovered, replace the gasket right away. If there is no mix in fluids, but only a loss of compression, the gasket still needs to be replaced since as the leak increases, even more compression will be lost and most likely a mix of oil and coolant will also eventually occur.

Prevention/Solution

To replace the gasket, all other surrounding parts in the way must be removed. The mating surfaces for the gasket, which are the top of the engine block and the bottom of the head, must be cleaned thoroughly. Proper gasket sealer should be used and it is critical that the head bolts be torqued down evenly according to manufactures specifications.

Particularly in automotive applications, circular grinding and sanding is necessary to design and maintain engine parts. For example, cylinder barrels of an engine need to be smoothed to just the right shape so the piston and piston rings dont create friction against the barrel walls. For large-production operations, honing machines perform this service on the manufactured parts. The machines come in different capacities and types.

How Honing Machines Work

Honing machines take the concept of hone grinding and automate it. Whereas normally a technician would attach a honing tool to the end of a spinning drill and insert it into the treated part, the honing machine performs this function on a mass scale with computer-driven equipment. The result is a precise internal surface to a circular cavity. The system is run either with pneumatic or hydraulic power sources.

Types

Vertical honing machines allow grinding work to form either an above-down or bottom-up angle. This works well for parts that have a single-directional cavity, such as engine cylinders. Horizontal honing machines, as the name implies, work from the sides with adjustable angles that allow the machine to work in a horizontal fashion. More specialized units can work with other, less common angles and applications.

Machine Management

Modern machines are run by computers and electronic gauges outside the machine. These control units run with computers and predetermined tolerance limits. The user punches in the desired specifications and the machine operates accordingly. When the machine reaches the desired tolerances or measurements, then the honing process stops so the treated part can be removed.

Cooling Systems

Grinding involves friction, which can create significant heat at high speeds or over time. Cooling systems are integrated into honing machines to avoid heat buildup that can damage machine parts. Modern machines will have coolant pumped into the grinding tool to circulate heat buildup away while production is occurring.

Maintenance

Because honing machines involve grinding, quite a bit of dust, residue and metal debris gets kicked up. This leftover material can get all over the machine and work area. Called "swarf," honing machines need to be cleaned of the waste material regularly. Honing machines also come with air filters that need to be changed regularly to rid swarf buildup near air vents. The honing oil that helps lubricate the machine parts and grease points of the machines gearing need to cleaned out and re-lubed as well.

There are six basic types of hitches: class I to V, and gooseneck hitches. Depending on the type of auto you have and the amount of weight you want to tow, you can review the facts first before choosing a Class III hitch.

Maximum Weight

The primary difference between the hitch classes is the maximum amount of weight that they are designed to tow. With a class III hitch you can haul up to 5000 lbs. GTW (gross trailer weight) or 500 lbs. tongue weight. The latter refers to the amount of downward pressure that can be exerted on the arm that is attached to the towing vehicle that connects to the towed vehicle.

Dimensions

In general, a class III hitch has a 2 inch receiver of rectangular shape. This is considered a standard size hitch for general towing needs. You can choose to have a class III hitch designed specifically for your auto or opt for a universal size available at nearly any auto parts store.

Compatible Vehicles

A class III hitch is best suited for three types of vehicles: vans, SUVs (sports utility vehicles) and mid-size pickups.