Jaguar XJ12 Valve Adjustment Cost
How Much Does a Valve Adjustment Cost?
Valve Adjustment Service and Cost
Engine valves are one of the hardest working components on any vehicle. They allow the engine to run by opening by mechanical force, and closing by spring at the right moment, hundreds of times per minute. Even with this task, they can last hundreds of thousands of miles, yet weigh much less than a screwdriver.
As the engine is used, the engine's valves are opened and closed forcefully hundreds of thousands of times. They are opened by mechanical force through the camshaft and valve lifters, and then slammed shut by forceful springs nearly instantly. This happens several hundred times per minute, and allows air into the engine each time the valve opens.
The familiar clattering heard from many engines is a sign that the valves missed an adjustment. Valve adjustments are scheduled by the manufacturer as part of the vehicle's scheduled maintenance. However, when the engine starts making these noises, in the absence of a lubrication issue, the valves are in need of adjustment.
Most commonly, valves that require adjustment do not prevent the engine from running, and the vehicle can be driven. Especially if the oil changes have not been completed on schedule, the longer the vehicle is driving, the more damage is being done. Failing to inspect and adjust valves can result in valve replacement, and lifter replacement.
Valve adjustments are normal maintenance items for many vehicles, and the service schedule is listed in the owner's manual. If the valves are wearing excessively, or require adjustment before the specified mileage, adjustment should be performed, and the engine oil may need to be upgraded.
Valve Adjustment Repair Information
When clattering is heard, it is isolated, even if a stethoscope is needed, and if the lifters are suspected, the valve cover is removed, and the valve clearance is inspected with a feeler gauge, which measures in increments to the thousandth of one inch. If the measurements are out of specification, a valve adjustment is recommended.
Valve adjustment procedures will vary from by engine, and even when the process is similar, the parts are different. When adjusting valves, it is nearly always required to remove the valve cover, PCV valve, coil packs, ignition coil wiring harness, and any other components obstructing removal of the valve cover. The valves are either adjusted by tightening a fastener with a torque wrench, or adding and subtracting spacers until the appropriate gap is reached. Once the valve clearance is set within factory specifications, the engine valve cover is reassembled, and the vehicle is tested for the noise.
When the valves are being adjusted, there are several seals and gaskets that are replaced, and many
When valve adjustments are not performed for too long, the amount of wear caused may prevent the valves from reaching proper adjustment, and repairs may be necessary. This is especially true if oil changes have not been performed when necessary. Following the manufacturer's specified scheduled maintenance interval will greatly reduce the risk posed by unadjusted valves.
Valve adjustment is a complicated process, and assumes a great deal of knowledge, Most people will never perform a valve adjustment, but professionals do them regularly. Trusting the valve adjustment to a verified technician, or even an engine specialist, is the best option in almost all cases.