First be sure the belt is tight and not slipping. Next, suspect internal leakage inside the rack and pinion assembly. A pressure test of the pump will confirm that but most mechanics will just replace the rack assembly based on the history. GM had a huge problem with "morning sickness" with their rack and pinion assemblies. That caused loss of power assist in only one direction at first until the fluid warmed up in about a minute or two. After a few weeks the problem affected turning in both directions. This was caused by grooves worn into the soft aluminum housing where the seals ride. They came up with a money-saving cobble job repair that was designed to get the vehicles out of the warranty period so their customers would have to foot the bill for the proper permanent repair. The best repair involves using a rack assembly rebuilt by one of the name brand aftermarket companies like Moog. They bore the housing out and insert a stainless steel liner to prevent the wear that caused the problem originally. Of course you could have a pump problem too instead of a rack and pinion assembly problem. One clue is if the power assist comes back when you increase engine speed, but that isn't always conclusive. At a higher speed the pump will be able to build higher pressure in spite of its wear, but it will also deliver higher volume which can overcome internal leakage inside the rack. A pressure test is the best way to find out which part is at fault.
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Tuesday, March 22nd, 2011 AT 7:48 PM
