We have a 1.9 diesel Citroen Berlingo Multispace, en excellent vehicle that does all that it is supposed to do (carries five people and their luggage or goods when required). We have one problem that we can't get to the bottom of and neither can the local garages.

When the weather gets hot (35°C) and the car has been standing over a hot road/in an open air carpark, the PAS goes very stiff and while it will ease off a bit after driving at 70kph+, as soon as one comes into a village or town and needs to slow down/park or otherwise manoeuvre at low speed, the steering goes stiff again. The steering pump was replaced about 18 months ago.

I did wonder if the drive belt wasn't driving the auxilliaries (including the steering pump) properly since we recently had to change the battery because it was almost dead flat, but a voltage check from the alternator showed approx. 14v however, at the time, the weather wans't quite so hot and the engine compartment wasn't either.

Any ideas?