BMW E36s are not known for unreliable power steering systems, however like any other car they develop problems as the vehicle ages. BMW E36 power steering problems are fairly common on higher mileage vehicles. The power steering hoses are a typical culprit of leaky power steering fluid. The power steering pump is also a common fail point on older E36s.
The good news is that most of the time a major power steering problem is caused by negligent maintenance that can be avoided. Unfortunately, the power steering system is an all too commonly neglected component on most vehicles. Owners who neglect their power steering often find that it leads to major repair bills later in the car’s life. Power steering fluid is rarely changed, if ever, and repairs are neglected until the steering becomes noisy.
In this article I will discuss the importance of the E36 power steering system and how it works, important preventive maintenance, and some tips on common power steering repairs.
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Power Steering System Importance
The purpose of a power steering system is to help the driver turn the steering wheel as easily as possible. Power steering became commonplace in vehicles during the 1950’s and 60s. Without power steering assistance it would take a lot of strength to turn the wheel, and many drivers would be unable to control their vehicle.
The BMW power steering system is typical of most vehicles, it has a power steering pump, reservoir, steering rack, and a fluid cooler. The fluid flow of an e36 system is: Reservoir – Pump – Steering Rack – Fluid Cooler – Reservoir. When working properly the power steering system helps provide excellent handling and control around sharp curves.
Power Steering Issues to Look Out For
There are a few symptoms that you should be checking/listening for from time to time to catch a developing power steering issue before it leaves you stranded on the side of the road.
Leaks
Honestly, every E36 my family has ever owned has had a power steering leak. Most of the time they are very slight, and are not worth addressing. On the otherhand, a large pool of power steering fluid on the floor of your garage is a serious problem. Usually the culprit will be the hoses, and they will have to be replaced.
Power Steering Rack Failure
The most common issue is that the power steering rack seals begin to leak. The seals begin to leak overtime due to wear and tear, but seal longevity is often significantly shortened due to failure to change old power steering fluid.
The most common symptom is a lot of play in the steering, and the tie rod boots will fill up with oil. You can check the rack by reaching under the front end of the vehicle and squeezing the tie rod boots. If there is liquid inside the boot it is likely that power steering fluid has escaped the leaking seals.
There are some DIY’s online and forums discussing how to rebuild the power steering rack and replace the seals. This is more labor intensive than simply replacing the rack, but it will save you some money. A new power steering rack will typically cost a couple hundred bucks.
Noisy Turning
Getting a lot of noise from underneath the hood whenever you turn the vehicle? If it is coming from underneath the hood you should pull the vehicle over immediately and check the power steering fluid. If you have low fluid in the power steering system or the power steering pump has gone bad driving will cause more significant damage to the power steering rack and pump.
Even if you check the fluid and it is full you are still not out of the woods. The power steering pump may not be circulating any fluid and thus causing that horrible whining noise. Symptoms of a bad steering pump are: (1) resistance turning; (2) and the whining noise. The shaft inside the pump will sometimes break and you will not have any power steering at all!
Power Steering Maintenance
There is some preventive maintenance that you can be performing on your power steering system from time to time to ensure the major components last their full lifetime.
Check your hoses
An important port of power steering preventive maintenance is to take a look at your hoses from time to time.
If you look under your BMW at your steering rack and oil cooler you will probably notice that they are covered in crusty black power steering fluid. This is normal, and doesn’t necessarily point to a serious leak. The rubber lines weep fluid as they age, and the banjo fittings tend to leak a bit overtime.
Check the fluid
In order to avoid expensive repairs such as power steering rack or pump replacement you should take a look at your power steering fluid every time you do an oil change. I certainly do not advise doing a power steering flush every oil change, but at least open up the reservoir and see what color your fluid is and determine if it’s low.
How do you know it’s time to change your power steering fluid?
Transmission fluid is a light red color, if it’s an opaque black color than it may be time to change it. However the color of the fluid does not in and of itself determine the integrity of the fluid. Black fluid certainly means that the fluid has gotten some use, however that does not mean that the fluid needs to be changed.
Power steering work on a BMW E36 is relatively easy to do, the worst part about it for me is how disgusting it is. Old transmission fluid is nasty, it smells bad, and when it gets on you it will take several days to leave your skin.
BMW E36 power steering systems take transmission fluid, not power steering fluid. If you own an E46 by any chance they also take the same fluid. BMW specifies Dextron III/Mercon Automatic Transmission Fluid for the power steering system. This is a good thing because it happens to be dirt cheap.
Power Steering Fluid Replacement
The best way to maintain your power steering and avoid serious repairs is to perform a “power steering flush” optimally every 30,000 – 40,000 miles. Most drivers do not perform a flush this frequently, but it’s a target that should be sought after. There are several different ways that you can perform a power steering flush. In the video above, I performed the easy flush because I was in a rush and did not have my tools with me at the time.
I prefer to take it a step further and remove one of the hoses from the power steering pump. The reason for this is that I end up removing more old fluid than in the video method. However, the video method does have it’s advantages because it takes so little time.
Tools needed
Jack & Jack Stands (or thick wooden blocks) Only for advanced flush
2 quarts Dextron III/Mercon ATF fluid
22 mm wrench or socket Only for advanced flush
Crush washers for the pump banjo fittings Only for advanced flush
A material (preferably plastic) to cover up the power steering pump pulley, and the serpentine belt if you are messy.
Large syringe or a gear oil pump for draining the power steering fluid (I even use a turkey baster in the video!).
Procedure
- Disconnect the air intake box and mass air flow sensor, and remove them from the engine bay. The power steering reservoir is located below the air intake, and cannot be accessed without removing these components.
- Open the lid on the reservoir and take a look at the fluid, note whether the level is low, and what color the fluid is. If the fluid is very low or not showing up at all on the stick, this would point to a leak. If the fluid is an opaque black color, it’s time to change.
- Use a fluid extractor, turkey baster, or fluid pump to remove all of the fluid in the reservoir.
- At this point some DIYer’s prefer to simply refill the reservoir, start the engine, and turn the steering wheel lock to lock. Afterwards they will repeat the process of removing the old fluid in the reservoir several times. I prefer to flush it by removing one of the banjo bolts on the side of the pump, because this gets more of the old fluid out of the system.
- Remove the high pressure line banjo bolt on the side of the pump, it’s a 22 mm bolt. Prepare for fluid to seep out as you remove the bolt.
- Next you’re going to turn the key in the ignition two clicks, and rotate the steering wheel slowly from lock to lock. Continue rotating lock to lock until there is no more fluid coming out of the pump.
- At this point you can replace the crush washer, and tighten the bolt on the pump. Afterwards refill the reservoir to between the minimum and maximum lines.
- Turn the key in the ignition two clicks and rotate the steering wheel lock to lock, afterwards check the fluid level in the reservoir. If it has dropped, put more fluid into the reservoir. Repeat this step until the fluid level no longer drops.
- Put the car on the ground, start the engine and rotate the wheel lock to lock, and then check the reservoir again to see if the level has dropped. If the level hasn’t dropped you’re done!
Power Steering Reservoir Replacement
Another common power steering maintenance job is replacing the power steering reservoir. If you are already changing your power steering fluid, I would highly suggest going the extra mile and replacing the reservoir with it since it requires very little extra work. The power steering reservoir is an important component that should be replaced from time to time because it has an inline filter that cannot be replaced separately. These filters can get clogged over time and cause problems with the flow of power steering fluid.
Annoyingly, BMW decided to install the reservoir nearly underneath the intake manifold. Just checking the dipstick requires the removal of a few components.
Procedure
- Remove the air intake box and the mass air flow meter.
- The reservoir is held in a bracket with a single 10 mm bolt. Remove the bolt and you will be able to get more space to access the two hose clamps.
- There are two hoses running to the reservoir, they are held on by two clamps that can be loosened with a flathead screwdriver. Loosen the two clamps and remove the reservoir from the two hoses.
- Install the new reservoir in the reverse order of removal.
- Refill the reservoir, check for leaks, insert the key into the ignition and turn the steering wheel lock to lock to bleed any air out of the reservoir.
- Your done!