In these engines the oil pump is adjustable, and the factory setting deliberately keeps the oil pressure low at low revs to reduce the drag of driving it. At low revs the stock pump works at around 1.8 bar, up to 2 bar at most. With a warm engine at idle this can fall further, and values below 1 bar have been reported. The camshaft adjusters feel the low pressure first, because the oil pressure itself is what holds the adjuster in place: this is where the clacking noise heard at idle comes from. The chain tensioner follows, which the same pressure tensions, and the timing chain therefore wears faster. The reference values for this engine family are 2 bar at idle, 3 bar at 2,000 rpm and 4.5 bar at 4,000 rpm. The turbocharger and the camshaft are lubricated from the same circuit. A strengthened oil pump raises the idle pressure by about 20 per cent. Repairing the pump costs between 800 and 2,800 euro, and replacing a worn chain is a further 1,200 to 3,500 euro.
What to check
- With a warm engine at idle listen for the clacking noise from the camshaft adjusters
- Read the fault memory and look for the camshaft timing codes P0011 and P0014
- Ask whether the oil pressure was measured warm at idle, and what it was