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If you own a Volkswagen Passat B5 or B5.5 equipped with the 1.8T engine (AWM, AEB, ATW, or AWT), you will eventually notice a strong burning oil smell inside the cabin, especially when sitting at a red light.
Ninety percent of the time, this is caused by a failing cam chain tensioner gasket and half-moon seal located at the very back of the cylinder head. As the rubber hardens with age, oil leaks out and drips directly onto the scorching hot exhaust manifold or turbocharger.
Replacing this gasket along with the valve cover gasket is a classic DIY job that prevents oil loss and stops that annoying burning smell. This guide covers the complete replacement process using the VAG special tensioner tool.
📊 Torque Specifications & Job Info
| Component | Torque Specification | Notes |
|---|---|---|
| Valve Cover Nuts (9x) | 7 ft-lbs / 10 Nm | Tighten in a cross pattern from inside out |
| Cam Chain Tensioner Bolts (3x) | 7 ft-lbs / 10 Nm | Clean threads thoroughly before installing |
| Camshaft Bearing Caps (If removed) | 7 ft-lbs / 10 Nm | Mandatory exact torque! |
🧰 Tools and Parts Required
- Cam Chain Tensioner Locking Tool: VAG Special Tool #3366 (This plastic tool compresses the tensioner and is usually included for free inside high-quality gasket kits).
- Gasket Kit: Includes the main Valve Cover Gasket, Spark Plug Tube Seals, the Tensioner Metal Gasket, and the Rubber Half-Moon Seal (Brands like Elring, Victor Reinz, or Mahle are highly recommended).
- RTV Silicone Gasket Maker: High-temperature oil-resistant sealant (e.g., Permatex Ultra Black or genuine VW sealant).
- 10mm Socket & Torx Bits: To remove the PCV lines, vacuum brackets, and valve cover nuts.
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🔧 Step-by-Step Installation Process
Step 1: Clear the Top of the Engine
Ensure the engine is completely cold. Remove the plastic engine cover. Unclip and remove the ignition coils, moving the wiring harness out of the way. Disconnect the brittle plastic PCV breather hoses at the back and top of the valve cover. Be extremely careful: these plastic pipes shatter easily if they are old.
Step 2: Remove the Valve Cover
Unscrew the nine 10mm nuts holding the valve cover down. Use a plastic trim tool or a rubber mallet to gently tap the side of the cover to break the old seal. Lift the valve cover off to expose the camshafts and the cam chain at the back of the head.
Step 3: Compress the Cam Chain Tensioner (The Crucial Step)
Locate the cam chain tensioner at the back of the cylinder head.
- Thread the VAG #3366 plastic compression tool into the designated holes on the tensioner.
- Turn the bolt clockwise slowly to compress the internal spring. This slacks the chain and lifts the tensioner body slightly.
- Warning: Do not over-tighten the plastic tool, or the threads will strip.
Step 4: Remove and Clean the Old Seals
Unbolt the three 10mm bolts securing the tensioner to the head. Carefully lift the tensioner up just enough (about 1-2 cm) to slide the old metal gasket and the rubber half-moon seal out from underneath using a pick tool. Do not drop anything into the engine oil valleys! Use brake cleaner on a lint-free shop rag to clean the mating surfaces until they are completely free of oil and old sealant.
Step 5: Apply RTV and Install New Gaskets
Slide the new rubber half-moon seal into place and position the new metal gasket under the tensioner.
- CRITICAL: Apply a small dab of high-temp RTV silicone sealant at the sharp corners where the half-moon seal meets the cylinder head. Failure to do this will cause the new gasket to leak immediately!
- Slowly unscrew and remove the #3366 plastic tool to let the tensioner expand back into place. Torque the three 10mm tensioner bolts to 7 ft-lbs / 10 Nm.
Step 6: Reinstall the Valve Cover
Clean the valve cover mating surface. Place the new valve cover gasket and spark plug tube seals onto the head. Apply a tiny dab of RTV silicone to the sharp corners near the camshaft caps. Lower the valve cover, install the 9 nuts, and torque them in a criss-cross pattern from the inside out to 7 ft-lbs / 10 Nm. Reassemble the coils and PCV hoses, and let the RTV cure for at least a few hours before starting the engine.