Bulletin: VW & Audi Oil Non-Return Valve

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26 Nov, 2019

Audi Models Affected:  Audi A3, Audi A4, Audi A5, Audi A6, Audi Q3, Audi Q5, Audi TT

Volkswagen Models Affected:  VW EOS, VW Jetta, VW Tiguan, VW golf

Engines: Volkswagen and Audi 2.0 Petrol engines (including CBZB, CCZA, CCZB, CCZC, CDLC, CDNB, CDNC)  **This is not a comprehensive list, just the most common we see

What we are seeing is the oil non-return valve that sits in the cylinder head and controls oil flow to the top of the engine is failing either partially or completely.  The non return valve dictates the amount of oil the hydraulic lifters and the variable valve timing units (VVT) receive.

A partial or complete failure of the control valve can cause a knocking noise from the timing chain area at the front of the cylinder head, and from our experience the noise in most notable at around 1500 – 2000rpm.  The reason is the variable valve timing (VVT) unit is not getting sufficient oil flow to allow it to advance and retard as required.  This results in a pronounced knocking sound at higher RPM but generally quite at idle.

You can test if this is the problem by disconnecting the plug for the VVT solenoid, if the noise goes away then you are likely on the right track.  There is no easy fix, cylinder head removal is required to access the control valve.  With the cylinder head off, replacement is easy as the valve just slides out and slide a new one in. 

If you are unsure call Southside Cylinder Heads on (07) 3343 5899.  We service Brisbane, Gold Coast, Sunshine Coast and Ipswich.

A failed return valve on the right, compared to a good one on the left
Bottom side of the failed return valve
Non-return valve fitted to the cylinder head

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