Car Repair: Basics Of A Valve Job
If you put a lot of miles on your car, or you’ve purchased a used vehicle that already has a lot of mileage, you’ll eventually need a valve job. The valves open and close, controlling how much air and fuel reach your engine’s cylinders. When there’s a problem, it can have an impact on your engine’s power. Cars usually need to have the valves looked at after reaching 80,000 miles. If neglected, you’ll likely notice the performance of your car declining. Below, I’ll describe a few reasons to have a mechanic look at your car’s intake valves. I’ll also provide a brief overview of a valve job.
Reasons To Have A Valve Job
A lot of older model cars that have a lot of mileage can experience problems with the intake valve. Because the valve plays a key role in allowing air and fuel into your car’s engine (through the cylinders), a problem can slowly deteriorate the power of your engine. Also, if a crack occurs in the cylinder head, coolant can reach the combustion chamber. When that happens, it can damage your engine’s cylinders. Finally, if your car has a burned intake valve, the engine may begin burning oil (you’ll likely be able to smell it). If you continue to drive with a faulty valve, you’ll notice a reduction in horsepower and even smoke billowing from your car’s exhaust.
What Is Involved?
A car technician will start by taking apart the cylinder head. He’ll want to check for tiny cracks or any signs of warping. If he finds any cracks - even small ones - he might be able to repair them through welding if the head is aluminum. If the cylinder head is made from cast iron, he may be able to fix the cracks with pinning (i.e. threading pins to seal the cracks). If he’s unable to repair them, the head will need to be replaced.
Once the cracks in the cylinder head have been repaired, it will usually be pressure tested for any leaks. Then, the technician will test the head for flatness to ensure it fits seamlessly with the head gasket. The valves and seats are then examined to check whether they need to be replaced or relined. A lot of repair shops will simply replace the valves instead of repairing them. Doing so helps to prevent failure due to overheating. Also, if the head’s seats are worn too badly, they’ll be replaced, as well.
Finally, the technician will look at the valve springs, including the retainers, to ensure they can provide sufficient pressure. If they’re damaged in any way, they’ll be replaced. Once all of the parts have been inspected, repaired, or replaced, the components are reassembled and the valves are “shimmed” to make sure they’re the right height.
Some drivers aspire to doing their own valve jobs. While it’s certainly possible with the proper equipment, it’s time-intensive and requires precision. Unless you’re unusually familiar with your car’s engine and cylinder head, you should have a trained mechanic perform the job.
