A power steering leak can be caused by a number of reasons such as a leaking power steering pump, a cracked power steering hose or a faulty steering rack.
The causes of a power steering leak include wear and tear caused by age, not maintaining the correct fluid level and even using the wrong fluid.
In this article, I'll explain how a hydraulic power steering system works, the most common places it can leak and how to fix them.
What Causes A power steering leak?
A leak from the power steering system is not that uncommon, especially in older vehicles.
You may notice a small deposit of dried fluid around the joints of some of the hoses, or the fluid in the top up reservoir may have dropped below the minimum recommended level.
Either way, here a few reasons why a leak can develop in the first instance:
1. Using the wrong power steering fluid
Not all power steering systems use the same type of hydraulic fluid. Some power steering systems use synthetic automatic transmission fluids (ATF). Others use silicone-based fluids. The suitability of a fluid to a system is dependent on the type of power steering pump, what viscosity of fluid it can pump, and the materials used in the various hoses and joints of the system.
If you are topping up the power steering fluid, be sure not to mix synthetic fluid with silicone-based fluid, as this could cause a lot of damage to the hydraulic system.
Using the wrong fluid may leave the system open to rusting or the build up of dirt. Or it may even attack seals, plastic component or rubber parts, causing them to leak.
The correct power steering fluid will be listed in the owner’s manual. It's also usually printed on the power steering reservoir cap.
2. Leaks Caused by Low Fluid Level
If the power steering fluid drops below the minimum level, it's going to put extra stress on all of the moving components.
Power steering pumps need an adequate supply of fluid to work, and they will wear out pretty quickly if they don't get enough lubrication. Continuous usage of the pump under with a lack of fluid will wear the pump internal components, seals, and rubber parts.
The steering rack is also susceptible to extra wear and tear if it's not getting a good supply of steering fluid.
A low fluid level may produce a whining sound when you turn the steering wheel. The first signs of a worn out steering rack or steering pump are leaks, and eventually this will lead to failure.
3. Normal Wear and ageing
High hydraulic pressures, normal usage, thermal fatigue, and environmental factors like humidity, heat, cold, and corrosion, will eventually wear out power steering components.
Seals and rubber components will often wear-out first. Leaks will inevitably appear once that happens.
However, a hydraulic power steering system is usually really durable. The lifespan of the hydraulic pump, rack, and seal can often be well over 100,000 miles depending on vehicle usage and weather conditions.
How To Diagnose A Power Steering Fluid Leak
Diagnosing the power steering fluid leaks is far easier once you understand what causes those leaks. Below is a simplified procedure to effectively diagnose the system.
1. Check The power steering fluid condition
First thing you need to do is check the condition of the power steering fluid. Look for abnormal color, consistency, or odor.
Assuming your vehicle is using modern ATF fluid, the normal color should be translucent red. If the fluid is an opaque red/brown or worse yet, dark brown/black with a burnt odor then you should replace all fluid in the system. A milky appearance could also indicate contaminated fluid that needs to be replaced.
2. Check The power steering fluid level
When checking the fluid condition, check its level in the top-up reservoir. The power steering system is a closed system, so any significant drop in fluid level is a clear indication of a leak.
3. Clean the components before inspection
A good visual inspection is crucial for finding out leaks. That’s why you need to prepare the system. Using a proper engine degreaser, thoroughly clean the power steering pump reservoir, hydraulic connections, hydraulic lines and the steering rack.
Clean away any oil, power steering fluid and engine grease. This is an important step that some mechanics skip, but it's vital if you want to spot small leaks.
4. Check for the hoses for leaks
Now that the system is ready for an inspection you can check all its connections. It’s not uncommon to find loose connections causing a power steering leak, especially after an engine repair.
Using clean gloves, run your hands along the power steering hoses checking for leaks. Follow the hoses feeding the steering pump from the reservoir, the hoses feeding the steering rack, and the hoses returning to the top-up reservoir.
If you suspect a leak on any of the hoses or joints, they may need to be replaced, depending on how badly worn they are.
5. Perform an engine running test
Once you've checked the condition of the hoses and pump, it's a good idea to perform a test with the engine running.
Make sure the top-up bottle is topped up to the required level and start the engine. Slowly turn the steering wheel all the way to the left and then all the way to the right.
While you are doing this, get a friend to keep an eye on the power steering reservoir. If they can see bubbles in the reservoir fluid, then you have air in the system. Air can sometimes get sucked in through a leaking joint or hose.
After completing the running test, re-check the power steering hoses, connections, power steering pump, steering rack and the power steering cooler for leaks.
3 Symptoms of A Power Steering Leak
1. Heavy steering at low speeds
If you find that turning the steering wheel is unusually difficult, this can point to a leak in the system. This is because a certain amount of steering fluid is needed to build up pressure to assist in turning the wheels.
It won't be as noticeable when the car is moving because there is less tire surface touching the road. But if you are having difficulty parking in a tight space or turning the steering wheel when stopped, then there is a problem with the power steering system.
2. Whining Noise when turning steering wheel
A lack of fluid in the system can cause the power steering pump to whine as it works to turn the wheels. The whining is caused by the internal moving parts of the pump not being lubricated sufficiently.
3. Steering fluid leaking onto the engine or pavement
Just like any other engine fluid leak, if see fluid on the ground or anywhere in the engine bay then you've got a leak. Most modern hydraulic steering systems use a red fluid that is easily spotted if it leaks.
In my experience, steering fluid leaks are often very small and take a long time to build up. You may not notice fresh fluid leaking, instead there may be a build up of dried fluid around the leak or where it collects.
Usually fluid from leaks will collect at the lowest point in the system, like at the bottom of hoses, on suspension arms or bushings or on the lower engine cover (if fitted).
How Do You Repair A Power Steering Fluid Leak
Depending on your findings during the diagnostic stage you may need to take one or more of the following actions:
1. For small leaks
If the engine running test results showed small leaks coming from the rack/gear or the power steering pump itself then you may use a good Power Steering Anti-Leak product.
These products are formulated to seal small leaks and lubricate seals and rubber components as well. I usually try to get my hands on the power steering leak stop by Lucas Oil. It can work well for small leaks that are caused by worn rubber seals. It's not going to work all of the time, but it's worth a shot if you want to keep your car going until you can overhaul the power steering system. You can find it here on Amazon.
Prestone also make a power steering fluid with leak stop incorporated into it. I've used this a few times on cars without leaks that just need topping up. Who knows, it may help to stop leaks too.
2. For Big leaks
If you have found any big leaks in your system, especially in the power steering pump and/or power steering rack/gear then you should consider replacing the part with a new one.
Using leak sealant products is not going to work for bigger leaks, or if any moving parts are not working properly. It may be more expensive, but it's going to be safer in the long run.