Five most common hydraulic rack failures
1. Ford Mondeo (2007-2015)
A loss of assistance in either one, or both, directions is caused allegedly by a manufacturing defect with the internal hydraulic piston that causes a loss in pressure. Look for a blocked reservoir filter, which causes the pump to be starved of fluid, which protests by becoming noisy.
2. Ford Galaxy MKIII and Ford S-MAX MKI
The same problems that strike the Mondeo afflict these other Ford models. Ignoring the problem can lead to pump failure. First, renew the rack and reservoir bottle and consider replacing the pump after the system has been flushed. Substituting the pump before replacing the rack and reservoir bottle is not recommended, because this can lead to the new pump failing very quickly.
3. Volkswagen Golf MKIV and Audi A3 (1998-2004)
These models can suffer from a very high failure rate, caused by either leaking fluid and/or excessive play in the rack. Water ingress is a particular problem, from a split, or badly-fitted gaiters. The resulting corrosion of the inner rack bar damages the internal seals, which then allows PAS fluid to enter the gaiters.
4. Mitsubishi Shogun (1999-2015)
The exposed pinion shaft at the top of the rack becomes corroded and damages the top seal, causing fluid to leak from the top of the rack. This can afflict other models as well, such as the Citroën C5 (2008-2016).
5. Ford Focus MKII, including C-MAX (2005-2012)
The steering rack piston wears a low point in the internal bore of the aluminium rack body, which contaminates the fluid subsequently. The increase in tolerance causes the rack gaiters to fill with fluid. Watch out for black PAS fluid and for the centre steering position to feel ‘sticky’ while driving.