Description

VW / Audi ADR 1.8 20V Cylinder Head Assembly – Valves & Camshaft Pre-Installed

This ADR 1.8 20V cylinder head is a brand new casting, machined to OEM tolerances and supplied as an assembled head with 20 valves, springs, retainers, stem seals, guides, hydraulic lifters and camshaft already fitted. It is the large-port 058-series casting used on the naturally aspirated ADR engine — not the small-port head fitted to most later turbo units.

For a workshop doing an ADR head replacement, the pre-assembled valvetrain removes the most time-consuming part of the job — lapping 20 valves, checking installed heights and torquing the camshaft caps — and lets you move straight to transferring the intake manifold, exhaust manifold, valve cover and timing components.

The ADR Engine — What Makes This Head Different

The ADR is the naturally aspirated 1.8 20V from the 058-series family, rated at 125 PS (92 kW) at 5,800 rpm with 168–173 N·m at 3,500–3,950 rpm. It was built for the longitudinal platform and fitted to Audi A4 B5, Audi A6 C4/C5 and VW Passat B5 between roughly 1995 and 2001. Because it is a non-turbo engine, the head is not exposed to the boost pressure and heat cycling that eventually crack turbo heads — but the ADR is now a 25-plus year old engine, and the heads fail for different reasons:

• Valve guide wear from high mileage — oil consumption, blue smoke on startup, poor emissions at inspection
• Valve seat recession on unleaded fuel with no lead protection
• Cracking between valve seats after overheating events — these engines run hot if the cooling system is neglected
• Warping from a failed head gasket or a low-coolant event
• Camshaft lobe and lifter wear where oil changes have been stretched

A warped or cracked ADR head cannot be reliably repaired once it has been resurfaced past the minimum thickness, and welding a 20-valve alloy head is a false economy. This complete cylinder head assembly is the correct replacement.

Large-Port Casting — Why It Matters

The 1.8 20V family was built with two intake port sizes: large port (ADR, AEB, AGU) and small port (most later 1.8T codes). The large-port casting flows noticeably more air on both intake and exhaust sides and continues that flow down the runners. On a naturally aspirated ADR the head is a straight OE replacement; on a turbo build it is the preferred starting point for high-power 1.8T conversions. Either way, it is not interchangeable with a small-port head — verify before ordering.

What’s Included – Fitted to the Head

The following components arrive pre-installed and ready to use:

• Cylinder head casting — new aluminium alloy, large-port 058 design, pressure-tested and flatness-checked
• 20 valves — 3 intake + 2 exhaust per cylinder, heat-resistant
• Valve springs, spring seats and retainers
• Valve stem seals — fitted
• Valve guides — pressed in
• Camshaft — DOHC, intake and exhaust
• Hydraulic lifters / tappets — pre-installed
• Camshaft bearing caps and bolts — torqued to specification
• Core plugs and oil gallery plugs — installed
• Valve seats — machined and sealing-checked

What You Transfer From Your Old Head

These parts are not supplied and must be reused or replaced during the job:

• Intake manifold and throttle body
• Exhaust manifold
• Fuel rail and injectors
• Valve cover / cam cover and gasket
• Camshaft sprocket and chain tensioner components
• Timing belt, tensioner, idler and water pump
• Head bolts — always fit new stretch bolts
• Head gasket and remaining gaskets and seals
• Camshaft position sensor, coolant sensors and wiring
• Secondary air injection components where fitted

Vehicle Compatibility

Fitted to longitudinally mounted VW Group models running the ADR 1.8 20V engine. Always confirm your engine code and OEM number before ordering — the transverse 1.8 20V engines use different head part numbers.

• Audi A4 B5 — 1.8 20V ADR (1995–2001)
• Audi A6 C4 — 1.8 20V ADR (select years, 1994–1997)
• Audi A6 C5 — 1.8 20V ADR (select years, 1997–2005)
• VW Passat B5 — 1.8 20V ADR (1996–2000)
• Other longitudinal applications where the ADR engine has been fitted (confirm via OEM number)

Why Buy This ADR Head From Us

• Brand new casting — never reconditioned, never welded, never resurfaced from a used head
• Correct large-port 058 casting for the ADR, not a small-port substitute
• Pressure-tested and vacuum-tested before dispatch
• Flatness checked to OEM tolerance — no surprises when you torque it down
• 20 valves, lifters and camshaft already fitted — hours of bench time saved per job
• 12-month warranty for trade and retail customers
• Crated for international freight; shipping to port or door

If you are sourcing an ADR 1.8 20V cylinder head for a Passat B5, A4 B5 or A6 rebuild, this unit restores the top end to factory condition without the turnaround time of a repair. Message us with your OEM number and a photo of your original head before ordering and we will confirm the casting and camshaft configuration.

Browse More VAG Cylinder Heads & Contact Us

• Full range: View our complete VAG cylinder head catalog.
• Fitment check: Send us your engine code and a photo of your original head on WhatsApp for a same-day compatibility confirmation and freight quote.