steering pump
 

My son has just bought a 2003 74Kmiles Mini Cooper, I have noticed the steering pump is making a sound when the steering is on lock left to right is this normal? I have spoken the Mini main dealer in Swindon and they quoted £500 for a new exchange unit!! I have looked on ebay and they are going for £100-200 from salvage breakers. Is it wise to buy one of these?. I would appreciate any contacts to purchase a replacement steering pump or any advice on my next step.