BMW Upper Timing Chain Guide / Tensioner Rail — 11311703717

Replace a worn or brittle timing chain guide with this BMW Upper Timing Chain Guide, also commonly referred to as the timing chain tensioner rail. BMW part number 11311703717 is the longer of the two upper timing chain guide rails used on many BMW inline-six engines.

The timing chain guides keep the chain properly aligned as it travels between the camshaft sprockets. While timing chains are designed for long service life, the plastic wear surface on the guide rails can become brittle, crack, or wear down after years of heat cycles and engine operation.

Once the plastic surface deteriorates, the timing chain can develop excessive movement and may eventually contact the metal portion of the guide. This can create significant rattling or clattering from the timing case and, if ignored, can contribute to timing chain damage or loss of proper engine timing.

If you're performing a timing chain or VANOS service on a higher-mileage BMW, replacing aging guide rails while the engine is already apart is highly recommended.

Product Details

• BMW Upper Timing Chain Guide / Tensioner Rail
• BMW Part Number: 11311703717
• Longer of the two upper timing chain guide rails
• Guides and supports the timing chain
• Works together with the timing chain tensioner
• Helps maintain proper chain alignment and tension
• Replacement for worn, cracked, or damaged original guides
• Recommended during timing chain and VANOS service

What Does a Timing Chain Guide Do?

The timing chain must follow a precise path around the engine's camshaft and crankshaft sprockets. Timing chain guides keep the chain properly positioned while helping control vibration and excessive movement.

The plastic wear surface also helps reduce the mechanical noise naturally produced by a chain-driven timing system.

As the plastic ages, it can become brittle or wear through. Once this happens, the chain may begin moving excessively or contacting surrounding components. The tensioner can only maintain proper chain tension if the guide rail it acts against is still in good condition.

Common Symptoms of a Worn Timing Chain Guide

• Rattling or Clattering — A worn guide can allow the timing chain to move excessively and create noise from the timing case.
• Startup Rattle — Timing chain noise may be especially noticeable immediately after starting the engine.
• Visible Guide Wear — Plastic surfaces may be grooved, cracked, broken, or completely worn through.
• Plastic Debris in the Engine — Pieces of a deteriorating guide may break away as the plastic becomes brittle.
• Engine Misfires or Timing Problems — Severe chain movement can affect proper camshaft timing.
• Hard Starting or Stalling — If the chain slips far enough, engine timing can be significantly affected.
• Potential Engine Damage — A failed guide can contribute to excessive chain slack or timing chain derailment.

Engine Compatibility

BMW 11311703717 is used on applicable versions of several BMW inline-six engines, including:

M50TU • M52 • M52TU • M54 • S52

Fitment varies by engine and production date, particularly on early M50 applications.

BMW Fitment Guide

Important Early M50 Fitment Note

Fitment on M50/M50TU engines varies by production date. Based on the application information, this guide is used primarily on later M50TU applications around the 1994–1995 model years. Verify your production date and original guide configuration before ordering for an early M50-powered vehicle.

Recommended During VANOS & Timing Service

If you're already removing the VANOS unit or servicing the timing system, take the opportunity to inspect the timing chain guides carefully. These engines are now old enough that even guides with relatively low mileage can suffer from age and repeated heat-cycle deterioration.

A new tensioner cannot properly control the timing chain if the guide it presses against is cracked, excessively worn, or damaged.

For a complete timing system refresh, we recommend inspecting the upper timing chain guides, upper timing chain tensioner, primary timing chain tensioner, chain, sprockets, and related VANOS components while everything is accessible.

BMW Part Number: 11311703717