Cold Old’s stiff steering due to worn rack

Hey there, time traveller!
This article was published 16/01/2004 (8044 days ago), so information in it may no longer be current.

QUESTION — The power steering on my 1991 Olds 88 seems stiff first thing in the morning. After I drive the car for a while, the steering gets easier to turn. The power steering fluid level is correct. Why does the steering seem stiff in the morning?

ANSWER — Your problem is caused by a worn steering rack. Seals inside the rack-and-pinion steering unit have worn into the aluminum housing, causing binding in the rack and fluid leakage past the seals when it is cold. After the power steering fluid and the steering rack warm up, the unit frees up and the steering wheel is easier to turn.

Take a look at the power steering fluid in the reservoir to verify my diagnosis. Normally, the fluid should be an amber or light brown colour. If the fluid looks black or grey, then aluminum particles from the steering rack have contaminated the oil.

Replacing the steering rack with a rebuilt or new unit is the best way of correcting the hard steering. Updated seals and rack components have been used for a few years, so a rebuilt or new unit has advantages over a used one from a salvage yard.

Be sure to flush out all the old fluid from the power steering pump and reservoir or the contaminated fluid will quickly start to wear the new rack. Use only power steering fluid to fill the reservoir. Automatic transmission oil may look similar, but has different additives in it that are not always compatible with the seals in the power steering. Leaks may be the result.

A wheel alignment is required after installing the rack because the adjustments for tire toe are done with the rack tie-rods that connect to the wheels.

QUESTION — The fuel economy has dropped on my 1996 Dodge Ram pickup. I checked it recently on a trip and it was about 20 per cent lower than when I first got the truck. The mileage is also lower than the identical truck my brother has. I recently had a tune-up done on the truck, so I was expecting the mileage should be back to original. How can I improve my mileage?

ANSWER — Testing fuel mileage accurately is difficult using only one or two fuel fill-ups. Gas tanks have an air pocket designed into the top of the tank to allow for expansion of the fuel when the tank is full. Depending upon how the truck was sitting when you filled it up, you can vary the amount of fuel enough to significantly alter fuel mileage calculations. Check the mileage averaged over several fill-ups to get a more accurate calculation.

Factors such as outside temperature, wind strength and direction, road condition, traffic volume and the way you drive can greatly affect fuel economy. A few quick accelerations from a stop, or passing cars on the highway, will quickly drop your mileage. These are reasons your fuel mileage may vary from that of other drivers.

There are mechanical reasons your mileage may have dropped. One common problem I see is a faulty engine thermostat. If the engine doesn’t reach optimum operating temperature, the fuel-injection computer delivers extra fuel because it senses a cold engine. How is your heater working? If it doesn’t seem as hot, then your thermostat is likely bad. Simply replacing a bad thermostat can improve your economy.

Another mechanical problem affecting fuel economy is an exhaust leak. If there is exhaust leaking out, then air also leaks into the exhaust system. The fuel-injection system oxygen sensor in the exhaust pipe detects the extra oxygen and tells the computer to deliver more fuel. Economy drops.

One of the tests a technician can do on your truck is to connect a “scan tool” diagnostic computer to your vehicle and read how the fuel-injection system is working. The tool shows if the truck’s computer is adding or taking away extra fuel from normal levels. The engine temperature is also accurately reported. Using this information, it is then easier to detect if something is wrong with the truck or if outside influences are affecting economy.

Jim Kerr is an experienced mechanic, instructor of automotive technology and freelance journalist. You can e-mail questions to Jim at the address below.

kerr.jim@sk.sympatico.ca