• A valve spring is coiled.coil image by Alison Bowden from Fotolia.com
  
  A valve spring, found in a car or truck, is a small, coil spring that closes the engine valve and keeps the lifter in contact with the camshaft. The lifter is part of the internal combustion chamber of an engine, and the camshaft connects to the cam, which are discs that produce reciprocating motion inside the engine. Checking your vehicles's valve springs is preventative maintenance. Often there are no signs that a valve spring is going bad, which is why internal diagnosis is important. Five main tools are necessary to check a valve spring.
  
  

Feeler Gauge

• A feeler gauge is a small, metal tool that looks almost like a mini ruler or straightedge. It is used to measure gap widths. When checking a valve spring, a feeler gauge is used to measure the width of a gap around or on top of the valve spring.
  
  

Junior Combination Square

• A junior combination square is a metal tool with a distinct right angle that is used by mechanics because of its compact size and light weight. The blades and heads of a junior combination square are smaller than regular squares. A junior square is helpful when rotating a valve spring to inspect for gaps.
  
  

Vernier Caliper

• A vernier caliper is used to measure the valve spring's height. Since you are measuring a spring with a round cross section, ensure that the axis of the valve spring is perpendicular to the caliper. A Vernier caliper is one of the most precise measuring instruments available. Use the metric units on the bottom scale to measure, not the calibrated units on the top scale.
  
  

Valve Spring Tester

• A valve spring tester is used to measure the valve spring's load capacity. The tester determines the amount of open pressure on each valve spring. The valve spring should compress against the valve spring tester to determine whether the load capacity of the valve spring meets the vehicle requirements. If the capacity is not high enough, the spring valves will need replacing.
  
  

Straightedge and Vise

• Any vise is a tool that holds items together securely inside its two metal jaws. A vice is used when determining the load capacity of valve springs. The valve spring tester is placed within a vise to collect a correct reading of the valve spring's load capacity. A straightedge is similar to a heavy-duty ruler. The straightedge usually has a nonslip texture and is used as a guide when measuring gaps. The straightedge and feeler gauge are often used together.