We call that "morning sickness" because it usually occurs in the morning when the power steering fluid is cold. It's due to internal leakage in the rack and pinion steering gear. The fix is to replace it. When it warms up, the teflon seals expand and seal better. That's when the power assist returns.
May, 18, 2012 AT 8:04 PM
Many thanks for the reply and advice.I'm a little puzzled as to what you're advising that I replace. The rack and pinion steering gear(whatever that is lol)OR the power steering fluid. Really hope its the latter. Many thanks again caradiodoc ; )
May, 18, 2012 AT 10:32 PM
Sorry, it's the steering gear that must be replaced. There may be a few places where you can buy repair parts but that is definitely not standard practice. Parts are not available for most brands so probably less than one out of a thousand mechanics have ever tried to repair a rack and pinion steering gear.
The problem is caused by wear in the "spool valve" housing. That is the shaft sticking up that the steering column is connected to. There are four teflon seals that look like small piston rings. When you turn the steering wheel, the center of that two-piece valve turns to expose, or open, one valve that lets pressurized power steering fluid in which pushes on the power piston to move the steering linkages, and a different valve opens to let fluid from the other side of the power piston out to go back to the reservoir. The high-pressure supply fluid and low-pressure return fluid are separated by those teflon seals. When one leaks, the pressurized fluid bypasses the power piston and goes right back up to the reservoir.
As the power steering fluid heats up, the teflon seals expand and form a better seal. That's when the power assist comes back.
Usually it's not actually the seals that are worn. They wear grooves into the soft aluminum housing that let the fluid bypass the power piston. General Motors had a huge problem with that back in the '80s and early '90s with their front-wheel-drive cars. Their less-than-conscientious fix was to install a new spool valve with new teflon seals. Rather than looking out for their customers' best interest, the goal was to spend as little money as possible to get the cars out of the 50,000 mile warranty period. After that it was up to the owner to foot the bill when the problem occurred again, which they all did. The new seals covered up the real problem for a little while but they didn't address those grooves in the housing.
The proper repair is to bore out the housing and press in a stainless steel insert. The major rebuilding companies are already doing that. Most typical rebuilt rack and pinion assemblies cost around $150.00. That's less than one third the cost of a new assembly. New ones are normally only ordered when the old one is being replaced under warranty and the manufacturer is paying the bill.
You may be able to replace the rack and pinion assembly yourself but an alignment will be needed after that. The inner tie rod ends are attached to the rack assembly. Where they are screwed together to the outer tie rod ends are the adjustments for "toe". Once the steering wheel is locked straight ahead, toe on each front wheel is adjusted to match each one to the steering wheel. Those adjustments are WAY to precise to do by eyeball or with a tape measure.