The only high pressure hydraulic hose on a car, apart from some brake lines, is the pressure hose on the power steering system. This fact makes leaks easy to identify, since it will be the only hose from which power steering fluid is seeping. Over time, the high temperatures inside the engine compartment causes the hose to harden, degrade and crack, which is not only messy- it is also dangerous, since a sudden rupture in the hose will cause a total loss of steering control.
However, replacing a high pressure power steering hose can be extremely difficult due the confined spaces in modern engine compartments and the complicate routing of the hose, so for this job you will need a repair manual and dedicated pipe wrenches, which are available from all dealers in automotive tools. You will also need a pan to catch the power steering fluid as it drains from the system, and rubber gloves to avoid skin contact with the fluid. More importantly you will need an OEM replacement hose and the correct grade of fluid for your car.
The steps outlined here are only a guide, and the exact procedure for your car will be outlined in the repair manual, which may include the removal or disassembly of unrelated components. Follow all the steps in the manual EXACTLY, and make sure you keep track of which fastener goes where by placing all bolts nuts, and screws in separate containers. So on to replacing the hose.
Step 1- Clean the engine
If the hose had been leaking for a long time, chances are that the engine will be covered in fluid and accumulated dirt. If this is the case, have the area cleaned with a steam wash to remove all fluid, accumulated dirt, and other gunk. However, be very careful that the water or steam does not go anywhere near wiring or electrical connectors. The last thing you want is damage to the electrical system caused by short circuits.
It is very important that the work area be clean, since it will prevent the introduction of dirt into the power steering system.
Step 2- Let the engine cool down
The nature of this job is such that it is impossible to do while the engine is hot. You will achieve nothing by burning yourself against hot parts such as the exhaust system.
Step 3- Locate the hose fittings
Consult the manual to identify the position on the steering gear where the pressure hose attaches, and use a pipe wrench to loosen the pipe nut. Note that this procedure can be very difficult due confined spaces and the tightness of the nut. You may have to remove other components to give yourself enough work space, so consult the manual on the correct and safe way to proceed.
Step 4- Drain the system
Before you completely detach the hose from the steering gear, place a suitable container under the car to catch the fluid as it drains from the system. There will be about one liter of fluid, or slightly more in the system, so make sure your container can accommodate this amount.
Step 5- Remove all retaining devices
All high pressure hoses are held in place by an assortment of clips, brackets, and holder to prevent chafing, and premature deterioration due to vibration. These devices can sometimes be very difficult to reach, so consult the manual on the best way to find, and remove them. Once all the retaining devices are removed, loosened, or relaxed, locate the attachment point on the power steering pump, detach the hose, and remove the hose from the engine compartment. However, take care that no fluid from it drips onto paint work.
Step 6- Fit the replacement hose
The replacement hose will be fitted with caps in, or over the treaded ends to prevent the introduction of dirt and contaminants in the hose, DO NOT remove the caps until you are ready to engage the threads with their attachment points. So carefully thread the new hose into position, all the while making sure that it follows the correct routing. Deviations from the proper routing means that the retaining devices will not hold it in place correctly and the new hose can suffer serious damage through chafing or vibration as a result.
Step 7- Make all connections
Attach the hose to the steering gear first, but only remove the protective cap over the threads once you are sure you can make the connection without introducing dirt into the system. Screw the threads in using only your fingers to prevent cross-threading the connectors and only use tools once the threads is engaged properly, and make sure the connection is tight, and secure.
With the hose routed correctly, it should now be possible to re-attach all brackets, clips, and other devices, but before you do this, screw the hose termination into position on the pump, but do not tighten it. You may need to manipulate the hose to get all the retaining devices into position, so leave the connection to the pump for last. As for the connection on the steering gear, make sure the connection on the pump is tight, and secure as well.
Step 8- Replace everything else
If you had to remove or disassemble unrelated components, replace everything in the EXACT reverse order of removal, and make sure you have no parts or fasteners left over.
Step 9- Refill, and test the system
At this point, the job should essentially be complete, so refill the reservoir to the indicated “Full” mark, and wait a few seconds to see if the level drops. It is normal if it does, since the fluid can take some time to reach all points in the system. If the level remains stable, close the reservoir, and start the car. However, DO NOT turns the steering wheel at this point, but allows the pump to circulate fluid throughout the system.
At this point you may hear strange noises from the pump, but they should disappear within a few seconds as the pump purges air from the system, and ONLY turn the steering wheel when the pump runs silently again. As soon as this happens, turn the steering wheel full lock from side to side a few times to stabilize the fluid level, and top up the level if required.
Step 10- Check for leaks
With the engine running, shine a flash light around the connections you’d made, and spend a few seconds checking each to confirm that they are tight, and there is no fluid leaking from them. If the unthinkable happens and you spot a leak, it would mean doing the whole job again, but then again, if you were careful in following the instructions in the manual exactly, it is unlikely that there would problems of any kind.
One more thing…
Power steering systems have a low pressure hose as well which connects to the bottom of the fluid reservoir, but it only runs to the pump, and its purpose is to feed fluid to the pump. This hose also hardens over time, and it very often leaks as a result, but replacing it is usually much less difficult than replacing its high pressure counterpart.
The procedure merely involves loosening the clamps or clips over the attachment points, and fitting a new length of oil resistant hose in its place.