I recently had two customers bring me two common problems on the same day, so I thought that it would be interesting to bring these issues to light.
We had a 2004 Acura TL with a power-steering pump whine and a 1999 Toyota Camry XLE V6 with no idle when cold. I find these problems interesting because there is no built-in warning light or technical code to identify them.
The Acura owner told me that when he starts the car in the morning, he hears a whining noise in the background that increases when he turns the steering wheel. Acura hydraulic-power-steering systems use a power-steering pump, power-steering reservoir, power-steering rack (rack and pinion) and power-steering hoses that tie it all together. The power-steering fluid starts in the reservoir and is pulled into the pump through the suction hose. The pump pressurizes the fluid and then delivers it to the power-steering rack. Once there is pressurized fluid at the power-steering rack, the steering wheel turns easily – even if the car is sitting still.
The benefit of a hydraulic system is the ease of power transmission and stiffness. Therefore, if air somehow gets pulled into or is introduced in the hydraulic fluid, the hydraulic will lose its stiffness. The air will also cause cavitation damage and severe fluid degradation. Therefore, as soon as air mixes with the fluid, the pump cannot properly pressurize the fluid. The power-steering pump is designed to pressurize fluid – not air. The air then causes the power-steering pump to make a loud whining noise.
There are two hoses that go to the power-steering pump. The suction hose pulls fluid from the reservoir, and the pressure hose pushes fluid to the rack. There is a small adapter on the pump that connects to the suction hose. The adapter mounts to the pump with a bolt, but it is sealed by a rubber O-ring.
The pressure hose also seals to the pump with a rubber O-ring. Over time, the rubber O-rings shrink and stiffen up. Once the O-ring hardens, it loses its sealing quality. So as the pump pulls in fluid through the suction hose, it also pulls in air because of the worn O-ring.
Once the suction O-ring is replaced, the pump stops pulling in air. We also recommend replacing the pressure side O-ring, because it will tend to leak.
That same day, we had a 1999 Toyota Camry that could not idle at all when cold. The customer reported that when she starts the car, it dies, and she has to keep her foot on the accelerator to rev up the RPMs to drive it.
This Toyota V6 is fuel injected and uses a throttle body for air delivery to the intake manifold. If the throttle plate is shut, there is almost no air traveling to the intake. Without air flowing to the intake, the engine won’t run. So there has to be a secondary air bypass to keep the engine running while the throttle is shut. This secondary air bypass is called an Idle Air Control (IAC) valve. The IAC, which enables air to travel from one side of the throttle plate to the other, will help control the idle when other consumers such as the air-conditioning system or the power steering steal horsepower from the engine during idle. There is a small gate inside the IAC that can change the flow of air during all of the different conditions of idle.
Throttle bodies have a tendency to build up carbon over time. Because the IAC valve is mounted to the bottom of the throttle body, it also begins to build up carbon. Once carbon fills up inside the IAC valve, it can get stuck. The carbon is harder when cold and tends to loosen a little when warmed up. We removed the IAC valve and found the gate jammed with carbon. We cleaned the valve and reinstalled it.
Both of these problems took only a couple of hours to solve and were easy on the budget.