Why Is My Car Engine Tapping?

A car engine is designed to run as quietly as possible, so when you start to hear pinging, tapping and knocking from under the hood, it's a sure sign something is not right. If you hear a sound that resembles a constant tapping, it could possibly be a problem with your hydraulic valve lifters.

What is a Hydraulic Valve Lifter?

Very simply put, a hydraulic valve lifter is the hollow steel cylinder which encases your internal piston.  It uses the oil pressure in your car to fill and empty the cylinder and cause your pistons to move up and down. Normally, the oil lubricates them so that they move relatively soundlessly, but if certain conditions exist or components are damaged, they make a characteristic tapping sound.

What Can Cause a Lifter to Fail?

Age is the most common reason that hydraulic valve lifters fail. Leaky, dirty and worn lifters can collapse, causing valve noise. Other reasons for valve noise include

  • low oil pressure
  • worn valvetrain components
  • worn valve seals
  • bearing wear or damage.

What Can I Check Myself?

First, check your oil level to make sure it isn't too low or overfilled. If it is low, check to see if oil is leaking from the car. Leaks can come from worn and damaged oil pans, valve gaskets that need replacing, a bad oil filter or a malfunctioning oil pump. If you find an oil leak, it's best to take your car to the auto repair shop, because simply adding more oil is a temporary fix that may eventually cause more serious damage.

What Will My Mechanic Check?

Your mechanic may run a machine diagnostic to pinpoint the problem, or he may manually check the entire valvetrain system. Once he has ruled out lubrication problems, he willl likely remove the valve covers and measure the clearance to see if it needs adjusting. He will also check the oil pump and filter to see if there is a blockage preventing the oil from properly lubricating the valves. He may then check for bent and broken pushrods and broken valve springs and inspect all the valvetrain components for damage or wear.

Should I Replace My Valve Lifters?

If you have an older car and one valve lifter is bad, it's usually recommended to replace all of the lifters, since another is sure to cause problems in the future. Valve lifter repair and replacement can be costly, and with very old cars, it may not be reasonable to repair them, since other worn parts will likely go bad in the near future. 

How Can I Prevent Hydraulic Valve Lifter Problems?

The best way to prevent serious valve problems is to have your car regularly serviced by a qualified professional. Many problems can be found early during something as simple as an oil change and can save you from expensive repairs down the road. Between maintenance appointments, be sure you are using the proper oil for your vehicle and check the level regularly.

Anytime you hear your engine making strange noises, it's best to take you car to a local auto mechanic or hydraulic repair shop. Repairing valves takes specialized knowledge, so make sure your mechanic is experienced in this type of repair. If you have hydraulic valve problems in an older car, a reputable mechanic will advise you whether or not your car is worth putting that kind of money into before he does the work.