How to Identify Hydraulic vs Solid Lifters in My Engine

by Floyd Drake III
Large engine maintenance image by Alexey Stiop from

Valve lifters are the rods running from the camshaft inside the engine to the valve train on top of the cylinder head. The function of a lifter is to follow the shape of the camshaft lobe, which raises and lowers the lifter, causing the valves to open and close with the proper timing. Solid lifters are mechanical, requiring periodic adjustments, whereas hydraulic lifters are self-adjusting and maintain a constant zero valve clearance, or lash. Differentiation between the two is accomplished by determining if there is a valve clearance, or lash, between the rocker arm and the top of the valve stem.

Step 1

Remove one of the valve covers with a socket wrench to access the valve-train assembly. When the valve cover is removed, the valve-train assembly will be in full view. On top of the valve-train assembly are the rocker arms, The rocker arms are "lifted" by the lifters on one side, while pushing down on the valves on the other.

Step 2

Determine the valve lash measurement location. Valve lash -- or the gap between the rocker arm and the top of the valve stem -- is measured at the closest end of the rocker arm when standing on the side of the car, for rear-wheel drive engines; or at the front of the vehicle for transverse front-wheel drive engines. The end of the rocker arm is on top of a spring that surrounds each valve stem.

Measure for any gap between the rocker arm and the top of the valve stem. On solid lifter assemblies, there is a gap between the rocker arm and the top of the valve stem. This is called the valve lash, which needs to be adjusted on solid lifter assemblies. Insert a feeler guage to identify a gap. The size of the gap does not matter, since the presence of a gap identifies solid lifters and the absence of a gap identifies hydraulic lifters. An illustration demonstrating this process is found on the DPG Nation link found in Resources.


  • Another way to quickly determine solid or hydraulic lifters is to push down firmly on the lifter end of the rocker arm. Hydraulic lifters will allow for some movement, whereas solid lifters will not budge.

Items you will need

  • Feeler guage
  • Socket wrench

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