Friday, Jul 24, 2026 The claims desk. Receipts included. POWERED BY LENZ ↗
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The Claim

An oil reservoir system is used to maintain zero valve clearance in an internal combustion engine valve train.

Verified by Lenz ·

The Short Version

The evidence shows that hydraulic valve-train components use an internal oil reservoir or chamber to keep valve lash at zero or near zero during operation. Technical sources consistently describe this as the operating principle of hydraulic lash adjusters or hydraulic tappets. The phrasing is somewhat simplified, but the underlying mechanism is accurately stated.

Caveats

  • This applies to hydraulic lash adjusters/tappets, not to all valve trains; many engines use mechanical adjustment instead.
  • The oil reservoir is part of a larger hydraulic lash-adjuster assembly that also relies on a plunger and check valve.
  • In practice, sources often describe the result as zero or near-zero lash under normal operating conditions, not an absolute condition in every circumstance.

The Receipts

  1. Hydraulic lash adjuster with internal oil pressure control

    Google Patents

  2. Hydraulic tappet

    Wikipedia

  3. Hydraulic Lash Adjuster Operation Explained | PDF

    Scribd

  4. Valve clearances - What, why, how?

    YouTube

  5. What Is a Valvetrain? Components, How It Works, and How to Protect It

    National Synthetics

  6. 216/235/261 Valve Adjustment Procedures

    Deves TechNet

  7. Valve Adjustment On BMW Single-Cam Engines

    BimmerLife

  8. Valve Lifter Basics and Beyond

    Engine Builder Magazine

  9. How Hydraulic Tappets Work

    HowStuffWorks

  10. Design and Performance of Hydraulic Lash Adjusters for Automotive Valve Trains

    SAE International

+ 23 more sources — see the full list on Lenz

Filed Under

Internal Combustion Engine

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